Eclogites and their geodynamic interpretation: a history

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/223579660 Eclogites and their geodynamic interpretation: A history Article in Journal of Geodynamics · August 2001 DOI: 10.1016/S0264-3707(01)00020-5 CITATIONS READS 35 217 1 author: Godard Gaston Paris Diderot University 101 PUBLICATIONS 1,218 CITATIONS SEE PROFILE All content following this page was uploaded by Godard Gaston on 04 January 2015. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. Journal of Geodynamics 32 (2001) 165–203 www.elsevier.nl/locate/jgeodyn Eclogites and their geodynamic interpretation: a history Gaston Godard CNRS-FRE 2316, Laboratoire de Pétrologie, Université Paris 7, T26-00 E3, 4 Place Jussieu, 75252 Paris, France Received 15 May 2000; received in revised form 22 March 2001; accepted 2 April 2001 Abstract Haüy coined the term eclogite, meaning ‘‘chosen rock’’, in 1822, but de Saussure had already observed rocks of this type in the Alps four decades earlier. Throughout the 19th century, the origin of eclogite remained an enigma, in spite of great progress in our knowledge of this rock. The first chemical analyses, carried out around 1870, showed that its bulk composition was the same as gabbro. Therefore, eclogite was thought to be either an igneous rock of gabbroic composition or a metamorphosed gabbro. This second hypothesis became preferred when progressive transitions were observed between gabbros and eclogites. In 1903, simply by comparing the molar volumes of gabbroic and eclogite parageneses, Becke inferred that eclogite was the high-pressure equivalent of gabbro. In 1920, eclogite was involved in the conception of the metamorphic facies by Eskola. However, a few researchers denied the existence of an eclogite facies, and claimed that high stress instead of high lithostatic pressure could generate eclogites. In the 1960s, consideration of the water pressure parameter also favoured the belief that eclogite was simply the anhydrous equivalent of amphibolite. Finally, eclogite was definitely considered as a high-pressure metamorphic rock following the development of experimental petrology and the application of thermodynamics. In recent years, the discovery of ultrahigh-pressure coesite-bearing rocks in the crust has drastically changed geologists’ ideas concerning the limits of eclogite-facies crustal metamorphism. Eclogites have been involved in several geodynamic theories. Around 1900, kimberlite studies favoured the idea that eclogite might be abundant in the interior of the Earth. In 1912, Fermor predicted the existence of a dense eclogite-bearing zone in the mantle. This ‘‘eclogite layer’’ hypothesis was still envisaged as late as 1970. The alternative ‘‘peridotite’’ hypothesis became preferred when experimental investigations demonstrated that the gabbroto-eclogite transition could not coincide with a sharp Mohorovičić discontinuity. Before plate tectonics, high-pressure belts were interpreted as remnants of ophiolite-bearing ‘‘geosynclines’’, metamorphosed by loading during thrust faulting. After the acceptance of plate tectonics, around 1970, the same high-pressure Alpine-type belts came to be considered as former oceanic crust, transformed into eclogite within subduction zones, and subsequently incorporated into mountain belts. Surprisingly, formation of eclogite in ‘‘subsidence’’ zones (i.e. subduction zones) had already been envisaged as early as 1931 by Holmes, the inventor of a convection-current theory. In the 1980s, many authors tried to apply the model of Alpine- E-mail address: gg@ccr.jussieu.fr 0264-3707/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0264-3707(01)00020-5 166 G. Godard / Journal of Geodynamics 32 (2001) 165–203 type high-pressure belts to eclogites enclosed within the gneisses of ancient orogens, but the question remains obscure nowadays. These eclogites have been involved in the ‘‘in situ versus foreign’’ controversy and in the unresolved enigma of ultrahigh-pressure metamorphism. The latter came under scrutiny in 1984 after the discovery of coesite and diamond in some eclogite-facies rocks. It has been a matter of considerable interest during the last two decades. Currently, the debate is focused on the geodynamic mechanisms responsible for the exhumation of these rocks, a question that will probably remain unresolved for part of the coming century. # 2001 Elsevier Science Ltd. All rights reserved. 1. Introduction When Haüy created the name ‘‘eclogite’’, meaning select or chosen rock, in 1822, he was impressed by the beauty of the rock and by the peculiarity of its mineral association. He certainly did not realise that this rock would prove to be a ‘‘chosen’’ rock in more than one sense. Indeed, over the last two centuries, eclogite has contributed to the birth of several major concepts in metamorphism. These include the ‘‘volume law’’ and the role of pressure, the existence of metamorphic rocks derived from igneous rocks, and the widely used concept of mineral facies. Moreover, eclogite has been involved in many geodynamic hypotheses. The occurrence of a hypothetical ‘‘eclogite layer’’ beneath the Earth’s crust has been under discussion up to late in the twentieth century. After plate tectonics had arisen in the 1960s, most eclogites came to be considered as resulting from subduction of oceanic crust. Finally, in the two last decades, eclogite and eclogitefacies rocks were also involved in the intriguing problem of ultrahigh-pressure metamorphism, after the discovery of coesite-bearing crustal rocks. In this paper, we attempt to survey two centuries of interrelation between metamorphic petrology and geodynamics by reviewing the history of eclogite, which once more naturally emerges as the ‘‘chosen rock’’ for such a task. The paper is divided into two main parts. We first report the advances in our knowledge of the rock (discovery, metamorphic origin, high-pressure conditions of formation: Section 2). Then, we present the various geodynamic theories and problems centred on eclogite (‘‘eclogite layer’’, subduction of oceanic crust, exhumation of ultrahigh-pressure rocks: Section 3). 2. History of a chosen rock 2.1. Discovery and definition René-Just Haüy (1822) (Fig. 1) coined the term ‘‘eclogite’’ from the Greek word eklogZ , meaning choice. In the second edition of his Traité de minéralogie, he wrote that ‘‘diallage [i.e. clinopyroxene] is considered the main mineral [of this rock], and constitutes with garnet a binary association to which can be unevenly added kyanite, quartz, epidote and lamellar amphibole. I gave to this rock the name eclogite, which means choice, or selection because its components, which do not usually coexist together in primitive rocks, as do the feldspar, mica and amphibole, seem to have chosen themselves to constitute a peculiar association. This rock occurs in Carinthia, Sau-Alpe and Styria [Austrian Empire]’’ G. Godard / Journal of Geodynamics 32 (2001) 165–203 167 Fig. 1. The abbot René-Just Haüy (1743–1822), mineralogist, member of the French Académie des Sciences and one of the inventors of the metric system. In 1822, he created the name eclogite, meaning ‘‘chosen rock’’ (# Bibliothèque nationale de France). (see note 1a in the Appendix for the French original text). Haüy’s collection, which is still preserved at the Muséum National d’Histoire Naturelle in Paris, contains 7 samples from ‘‘Pays de Bayreuth’’ (Bavaria, Germany) that are labelled éclogite (see note 1b in the Appendix). Thereafter, many petrologists have claimed that Haüy was the first to have discovered eclogites, but this assumption is unfair since others had observed eclogites before he created the name. Indeed, during the Neolithic, humans already appreciated eclogite for its high density and hardness, and used it to make tools, particularly in Europe (e.g. Lohmann, 1884; Franchi, 1904; D’Amico et al., 1995; Hovorka et al., 2000). From a scientific point of view, we owe the first description of an eclogite to Horace-Bénédict de Saussure (1779–1796: Fig. 2). In his Voyages dans les Alpes, he mentioned a ‘‘beautiful rock that is not described yet’’ and that he had found as pebbles in the Rhone valley near Geneva. The rock was dense, hard, and made of garnet crystals in a green matrix of ‘‘jade’’ (pyroxene ?) and ‘‘schorl’’ (prismatic amphibole ?). In 1767 and 1774, he observed similar rocks cropping out at Le Brévent near Chamonix (Savoy) and Montjovet (Aosta Valley: see note 2 in the Appendix). The first occurrence is certainly connected with the well-known Lac Cornu eclogite, only 2 km away. The beauty of the rock of Montjovet particularly impressed him: ‘‘Cette pierre paroıˆt au soleil de la plus grande beauté.’’ De Saussure’s collection, which still exists in Geneva (see Lanterno, 1976), contains a score of eclogite, eclogite micaschist, and glaucophanite specimens that were sampled in various parts of the Alps (see note 2 in the Appendix). Déodat Gratet de Dolomieu also mentioned the occurrence of rocks made of green ‘‘schorl’’ and garnet in ‘‘primitive 168 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Fig. 2. Horace-Bénédict de Saussure (1740–1799) by Jean-Pierre Saint-Ours, 1796. Although only the third man to climb Mont-Blanc, Saussure was the first to describe, under various names, eclogites, eclogite micaschists and glaucophanites from the Alps (see note 2 in the Appendix; # Bibliothèque nationale de France). mountains’’, and he discussed at length the reason why these two minerals crystallise together (Dolomieu, 1794). Finally, the great German geologist Abraham Gottlob Werner knew of some eclogites in the Austrian Alps and southern Germany, notably the famous occurrence of Silberbach. He described them as composed of garnet, ‘‘omphazit’’ and, occasionally, ‘‘cyanit’’ (Werner, 1817). The name eclogite has proved useful, since it was soon used by European authors to describe rocks from southern Germany and Austria (Leonhard, 1823), the Western Alps (Necker, 1828; Fournet, 1841; Favre, 1867), Vendée in western France (Rivière, 1835, 1844), Saxony in Germany (Naumann, 1838; Müller, 1846), Bohemia (Hochstetter, 1855; Patton, 1887), Venezuela (Wall, 1860), Norway (Hiortdahl and Irgens, 1862; Reusch, 1877, 1883), Galicia in Spain (Macpherson, 1881), Silesia (Traube, 1889) and Scotland (Teall, 1891). However, a lot of confusion existed in many of these early studies, which—it should be remembered—were performed without the microscope. While garnet was recognised without difficulty, the pyroxene matrix was referred to either as ‘‘diallage’’, ‘‘omphazit’’, ‘‘körniger Strahlstein’’, ‘‘schorl’’ or ‘‘smaragdite’’. Smaragdite, a name created by G. Godard / Journal of Geodynamics 32 (2001) 165–203 169 Fig. 3. Retrogression structures in eclogite according to Alfred Lacroix (1891). Garnet crystals (25) are corroded by a ‘‘kelyphite’’ made of amphibole+plagioclase (see enlargement B); omphacite (20) is also partly replaced by a clinopyroxene+oligoclase symplectite (21) (see enlargement A); eclogite from Kerscao, Plounevez-Lochrist, Pays de Léon, France. Fig. 4. Secondo Franchi (1859–1932), engineer of the Reale Ufficio geologico d’Italia. He studied the ‘‘micascisti eclogitici’’ of the Alps and, in 1902, observed the reaction jadeite+quartz!albite (see Stella, 1933; photograph from Novarese, 1938; # Servizio geologico d’Italia). 170 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Fig. 5. The Finnish petrologist Pentti Eskola (1883–1964). While studying the eclogites of Norway in Oslo (1920, 1921), he developed the concept of mineral facies which, among others, comprises an eclogite facies (# Geological Survey of Finland). de Saussure (1779–1796), was a greenish but poorly defined silicate. Omphacite, also a green mineral, had been named by Werner (in Hoffmann and Breithaupt, 1815, vol. 2, part 2, p. 302) after the Greek omjax meaning ‘‘green grapes’’, with reference to its colour. Haüy (1822) regarded Werner’s omphacite as a green variety of his ‘‘diallage’’ (i.e. clinopyroxene). Because clinopyroxene in eclogite generally displays a beautiful emerald green colour, the name omphacite was finally adopted, while the use of the word ‘‘smaragdite’’ became restricted to green amphiboles that are also common in eclogites (see Drasche, 1871). 2.2. Early petrological investigations The polarising microscope, which had been in use since the middle of the 19th century (see Hamilton, 1992), led to a great progress in the petrographical knowledge of eclogite. Thus, in the years 1880– 1920, several important monographs were published on eclogites from Bavaria and Austria (Riess, 1878; Lohmann, 1884; Ippen, 1892; Düll, 1902; Hezner, 1903; Kieslinger, 1928), France (Lacroix, 1891; Joukowsky, 1902; Brière, 1920), California (Holway, 1904), and Norway (Eskola, 1921). These works include precise mineralogical and petrographical descriptions of the eclogite parageneses, together with details on two important structures that commonly occur in eclogite, namely kelyphite coronae around garnet crystals and symplectites developing from omphacite (Fig. 3). The name ‘‘kelyphite’’ was coined by Schrauf in 1882 from the Greek word kelujo&, meaning shell, to describe coronae between garnet and olivine in peridotites (Schrauf, 1882; see Godard and Martin, 2000). It also became used to describe amphibole-bearing coronae around garnet in eclogite, the nature of which is, however, much different (Fig. 3b). Holland (1896), Sederholm (1916) and, principally, Hezner (1903) carried out detailed studies of this metamorphic reaction. The first elegant interpretation of these coronae was proposed by Fermor (1912) who considered them as resulting from the breakdown of garnet during decompression (see note 3 in the Appendix). G. Godard / Journal of Geodynamics 32 (2001) 165–203 171 Omphacite replacement by symplectites, the second common structure (Fig. 3a), was also observed by several authors (e.g. Becke, 1882; Patton, 1887; Teall, 1891; Lacroix, 1891; Franchi, 1902a; Hezner, 1903; Grubenmann, 1904–1907; Weinschenk, 1904) and described in detail by Brière (1920) and Eskola (1921). These authors painstakingly identified the clinopyroxene+plagioclase and amphibole+plagioclase associations among the cryptocrystalline products that replace the omphacite. This process of omphacite replacement was apparently first understood by the Italian petrologist Franchi (1902a) and afterwards by Eskola (1921). It was interpreted as resulting from the exsolution of the jadeite molecule from omphacite, which results in albite production: 1 omphacite [Jadeitex Augite1 x]+x quartz ! x albite+(1 x) augite. To arrive at this conclusion, we had to wait for improvements in our knowledge of the jadeitic clinopyroxenes. The discovery of the relationship between jadeite and eclogite is in itself a long story. Jade was known since Neolithic times and has long been used for manufacturing hatchets and jewels (see Bishop, 1906). The Indians of Central America called it ‘‘chalchihuilt’’, and the Chinese also knew this stone as ‘‘Yü’’, which they collected in Yü Shan (the ‘‘mountains of jade’’). It was first described in Europe by Nicolás Monardes, in 1565, as ‘‘la piedra dela yjada’’ (the colic[-curing] stone), because of its (doubtful) curative powers. This name was strangely translated as ‘‘pierre de jade’’ by French lapidaries, and thus became our ‘‘jade’’. Early mineralogists such as Haussmann (1813), Hoffmann and Breithaupt (1815), Haüy (1822) and, principally, Alexis Damour (1863, 1865, 1881) differentiated two main species of jade, one made of a calcic amphibole (‘‘nephrite’’) and the other of a new Na–Al-bearing silicate that Damour called ‘‘jadéite’’. At first, Damour (1863, 1865) believed that his jadeite was a kind of ‘‘wernerite’’ (i.e. scapolite), because of its chemical formula. However, Krenner (1883), Arzuni (1883), Cohen (1884) and Clarke and Merrill (1888) clearly established, from the physical and optical properties of the mineral, that it was actually a sodic and aluminous clinopyroxene. The connection between eclogite and jadeite was first suspected by Damour, who showed in 1881 that the ‘‘green substance’’ (i.e. omphacite) of an eclogite from Fay-de-Bretagne, in Western France, was close to jadeite in composition. Finally, several authors established that omphacite in eclogite was a solid solution of augite and jadeite, with minor aegyrine content (e.g. Zambonini, 1901; Bishop, 1906; Washington, 1922; Perrier, 1924; Sahlstein, 1935). Franchi (1900) (Fig. 4) also showed that the jadeite-bearing rocks of the Alps are ordinarily associated with eclogites. The same author (Franchi, 1902a) was apparently the first to describe the well-known reaction jadeite+quartz!albite. He also interpreted the replacement of omphacite by symplectites in eclogite as resulting from jadeite exsolution (see above). Eskola (1921) further developed this interpretation. 2.3. Metamorphic versus magmatic origin While our knowledge of eclogite progressed, the problem of its origin remained an enigma. The debate turned on one main question: Is eclogite a metamorphic or a magmatic rock? Around 1820, Ami Boué developed the new concept of metamorphism, as a consequence of Hutton’s magmatic theory (e.g. Boué, 1820, 1824). Although Boué had already used the French word métamorphose, it is to Lyell (1830–1833) that we owe the term ‘‘metamorphism’’ (from mEta [trans] and morjZ [form]). During almost all of the 19th century, the concept was restricted to the effect of temperature and the action of fluids, and regarded as applicable to sedimentary rocks (see: Daubrée, 1859; Delesse, 1857–1961; Hunt, 1884; Williams, 1890; Zittel, 1899). Temperature 172 G. Godard / Journal of Geodynamics 32 (2001) 165–203 and fluids were considered as the driving forces for mineralogical transformations, ‘‘pressure’’ (in fact, stress) being responsible only for schistosity development. As for the eclogites, a few authors began to consider them as metamorphic rocks (e.g. Lipold, 1855; Lüdecke, 1876; Riess, 1878; Zirkel, 1894; Düll, 1902; Hezner, 1903; Becke, 1903; Grubenmann, 1904–1907; Brière, 1920). Their main argument was that eclogites are foliated just as any other metamorphic rock. They have thus undergone dynamometamorphism together with their surrounding gneiss whose metamorphic origin was undoubted. Other authors, however, believed that they were magmatic rocks (e.g. Hiortdahl and Irgens, 1862; Brøgger, 1880; Kolderup, 1903; Eskola, 1921; Dal Vesco, 1953). This gave rise to a long controversy that apparently degenerated into a chauvinistic quarrel between Austrians and Germans who favoured the metamorphic origin, on the one hand, and Scandinavians who preferred the magmatic hypothesis, on the other (see Perrier, 1924). It was also partly due to a misunderstanding since some of the purported magmatic eclogites were actually garnet-pyroxenite layers within peridotites. Such rocks are not considered as true eclogites nowadays (e.g. Ravier, 1964; Smulikowski, 1964a). Meanwhile, the first chemical analyses of eclogite and its constituent minerals (e.g. Mauthner, 1872; Gerichten, 1874; Dathe, 1876; Riess, 1878; Schuster, 1878) clearly revealed that eclogite has the bulk composition of a gabbroic rock, although its mineral composition was far removed from that of a gabbro. This conclusion did not solve the problem of the origin, as it was compatible with both hypotheses: eclogite either could be a magmatic rock of a gabbroic composition or derived from gabbro by metamorphism. This last idea, however, was rather innovative since the concept of regional metamorphism had so far been applied only to sedimentary rocks. The study of glaucophane-bearing rocks, with which eclogites are commonly associated (Section 3.2), helped to elucidate the question. Progressive transitions were observed from unmetamorphosed gabbros or basalts, to glaucophane-bearing metabasites, and finally glaucophane eclogites (e.g. Bonney, 1879; Koto, 1887; Lepsius, 1893; Franchi, 1895; Holway, 1904; Smith, 1906; Zambonini, 1906; Lacroix, 1941). This was a major argument in favour of the metamorphic origin of eclogites and their associated glaucophanites. More recently, several authors (e.g. Bearth, 1959, 1970; Coleman and Lee, 1963) have described glaucophanites with preserved pillow-lava and breccia structures. Nevertheless, the metamorphic origin was not easily acknowledged and remained disputed for a long time. Brière (1920), for instance, argued in her thesis that the French eclogites had resulted from metamorphism of gabbroic rocks, not only because eclogite compositions were the same as gabbros but also because they followed variations typical of a gabbroic series. In 1981, I had the chance to meet Yvonne Brière, when she was 92. She told me that the members of her thesis examining board, at La Sorbonne University in Paris, had severely criticised her hypothesis of a metamorphic origin. She was thus very pleased to learn, 61 years later, that her opinion was now widely accepted. Surprisingly enough, among the supporters of the magmatic origin was the great Finnish petrologist Pentti Eskola (Fig. 5) who considered the eclogites of Norway as having crystallised at high pressure from an ‘‘eclogite magma’’ (Eskola, 1921). He attributed foliation to ‘‘stress during consolidation’’. Even the secondary kelyphite (see Section 2.2) was attributed by him to a late magmatic (re)crystallisation stage. Thus, the greatest contributor to the concept of metamorphic facies believed that eclogite was a magmatic rock, although he had apparently changed his mind by 1939 (i.e. Eskola, 1939). A few other petrologists believed in a metamorphic origin but pre- G. Godard / Journal of Geodynamics 32 (2001) 165–203 173 ferred calcareous sediments as the protoliths instead of gabbro (e.g. Ghosh, 1941; Smulikowski, 1964b; Vogel and Garlick, 1970). This strange idea was apparently due to confusion with metamorphic calc-silicate rocks made up of grossular-rich garnet and jadeite-free clinopyroxene, which vaguely resemble eclogite. Finally, a consensus gradually emerged. Eclogite was thought to result from the metamorphism of gabbroic or basaltic rocks, for three main reasons: (a) Progress in geochemistry showed that eclogites have all the features of gabbros (major and trace elements, REE, isotopes) and show variations typical of gabbroic differentiation; (b) The structures of the former gabbro or basalt protoliths were still recognizable in cases where eclogite-facies metamorphism was static (e.g. Chenevoy, 1958; Miller, 1970; Vraná et al., 1975); (c) The gabbro-to-eclogite transformation was confirmed experimentally (Ringwood and Green, 1966; Green and Ringwood, 1967a, 1972). Nevertheless, several authors nowadays accept that some mantle eclogites (griquaite, grospydite) could have been formed from magma at high-pressure conditions. 2.4. The concept of high-pressure eclogite-facies metamorphism When the connection between eclogite and gabbro came to be considered around 1900, the following question arose: How can we account for such a great difference in mineralogy between gabbro and eclogite, while their chemical compositions are so similar? As it turned out, pressure was an elegant answer to this question. The well-known ClausiusClapeyron equation, which expresses the pressure-volume control of reactions, clearly predicts that an increase of pressure should lead to the formation of minerals of higher density. The first application of this basic idea to rocks, often referred to as ‘‘the volume law’’, was apparently due to Lepsius (1893). The Austro-Hungarian petrologist Friedrich Becke, the inventor of the famous ‘‘Becke line’’ method in microscopy, was the first who applied the volume law to eclogites (Becke, 1903). Simply by comparing the molar volumes of gabbroic and eclogite parageneses (Table 1), he concluded that eclogite was the high-pressure equivalent of gabbro. This constitutes, in my opinion, one of the most ingenious ideas of the whole history of petrology. The conclusion was soon adopted by several researchers (e.g. Grubenmann, 1904–1907; Fermor, 1912, 1913 [see note 3 in the Appendix]; Boeke, 1915; Eskola, 1920, 1921), many of whom, however, did not refer to Becke’s work. It eventually received an experimental confirmation 63 years later. In the same period, the notion of mineral facies was being developed. Barrow (1893) introduced the concept of progressive regional metamorphism and used critical index minerals to define metamorphic zones. Van Hise (1898) proposed four ‘‘depth zones’’, whereas Grubenmann (1904– 1907) distinguished three consecutive zones with increasing depth (i.e. epi-, meso- and catazones), eclogite belonging to the deepest zone. The introduction of pressure as a new independent intensive variable in addition to temperature led to an improvement of the concept by Eskola (1915, 1920, 1921, 1929, 1939) and Becke (1921), with the participation of Goldschmidt. According to Eskola, rocks belonging to a given facies originated under similar temperature (T) and pressure (P) conditions. At these particular P–T conditions, their mineral composition is dependent only on the bulk chemical composition, while a given composition results in the same set of minerals, whatever the mode of crystallisation, metamorphic, magmatic or even hydrothermal. Indeed, as suggested by the ‘‘volume law’’, eclogite and glaucophanite were considered as having formed under high-P/high-T and high-P/low-T conditions, respectively. They were naturally chosen as 174 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Table 1 Table based on the work of the Viennese petrologist Friedrich Becke (1903), applying the ‘‘volume law’’ to eclogites. Becke compared eclogite and gabbroic parageneses of the same composition. From their differences in molar volume, he inferred that eclogite was the high-pressure equivalent of gabbro. Molar volumes are expressed in cm3 mol 1; R=(Ca, Mg, Fe). Note that the glaucophane formula given by Becke is not correct Gabbro (Olivin, Augit, Basischer Plagioklas) Augit Ca Mg Si2 O6 Mg Al2 Si O6 Eklogit (Omphacit, Granat, Quarz) = 68 68 Granat R3 Al2 Si3 O12 121 Granat + Quarz R3 Al2 Si3 O12 Si O2 123 22.8 136 Augit + Anorthit Ca Mg Si2 O6 Ca Al2 Si2 O8 = 68 101.1 169.1 Olivin + Anorthit Mg2 Si O4 Ca Al2 Si2 O8 145.8 = 43.9 101.1 Granat R3 Al2 Si3 O12 121 145.0 Albit des Plagioklases Na Al Si3 O8 = 100.3 Na-Al-Silikat des Omphacit [Jd] + Quarz Na Al Si2 O6 Si O2 64.6 22.8 87.6 Nephelin + Albit Na Al Si3 O8 Na Al Si O4 = 100.3 59 Glaukophan Na2 Al2 Si4 O12 137 Jadeit 2 (Na Al Si2 O6) 122.8 156.3 = type rocks for the ‘‘eclogite facies’’ (Eskola, 1920, 1921, 1929; Becke, 1921) and ‘‘blueschist facies’’ (Eskola, 1929, 1939). We should clearly understand that, in Eskola’s mind, rocks of a given facies could be either magmatic or metamorphic. Although he accepted that metamorphic eclogites might exist, he favoured a magmatic origin for eclogite (see Section 2.3). Over the next decades, however, it became evident that magmatic rocks could not crystallise over a large range of T. There are no magmatic rocks in the low-T ‘‘greenschist facies’’, for example. Therefore, the concept of mineral facies (Eskola, 1920, 1921) evolved into that of metamorphic facies (Eskola, 1929, 1939). If it has any basis in reality, Eskola’s eclogite facies should not only comprise basic rocks but also ultrabasic and pelitic rocks as well. Garnet peridotites have been regularly recognised as the ultrabasic member of the eclogite facies (e.g. Eskola, 1921; O’Hara, 1967; Medaris and Carswell, 1990). On the other hand, pelitic eclogite-facies rocks are extremely rare. Stella (1894) provides us G. Godard / Journal of Geodynamics 32 (2001) 165–203 175 with the first example of such a rock. He discovered micaschists in the Western Alps that showed analogies with eclogite, which he called ‘‘micascisti eclogitici’’ (see Compagnoni et al., 1977). These eclogite micaschists, made of white micas, garnet, quartz, jadeite-rich clinopyroxene and rutile, were further studied by Franchi (1900, 1902a). They remained without an equivalent for a long time, and eclogite-facies pelitic rocks, whether described as ‘‘eclogite micaschists’’, ‘‘mucronites’’ or Mg-rich talc-bearing ‘‘whiteschists’’, are still exceptional nowadays (see Mottana et al., 1990, pp. 35–46; e.g. Sobolev and Shatsky, 1990; Tagiri and Bakirov, 1990; Wallis et al., 1997). In most cases, the gneisses enclosing eclogites apparently show no evidence of eclogite-facies metamorphism. Later, this observation led to a controversy about the mechanism of eclogite emplacement within gneisses (in situ versus foreign origin: see Section 3.3). The almost total failure to recognise eclogite-facies parageneses of pelitic composition encouraged some researchers to reject the existence of an eclogite facies (e.g. Wieseneder, 1935; Backlund, 1936; Korzhinskii, 1940; Buddington, 1943; Sørensen, 1953; Roever, 1955; Chenevoy, 1958) and to raise objections against the high-pressure theory (see: Ebert, 1936; Nikitin, 1942; Smulikowski, 1964b). Most of these authors claimed that high stress rather than high lithostatic pressure could generate dense mineral assemblages. In this manner, eclogites might have formed at moderate depths in the crust during intense dynamometamorphism. Similar hypotheses, invoking stress or ‘‘tectonic overpressure’’, were repeatedly put forward until recently, although considered heretical by the majority (see Smith, 1995, pp. 336–341). Even more surprising hypotheses were also envisaged involving contact metamorphism, hydrothermal activity or metasomatism (e.g. Hentschel, 1937; Taliaferro, 1943; Switzer, 1945; Smulikowski, 1960). In the 1960s, a new concept arose, namely water pressure (PH2 O ), which led some researchers to minimize the role of pressure in eclogite metamorphism. Early experimental work (Yoder and Tilley, 1962) suggested that eclogite stability depended mainly on PH2 O . Eclogite, an almost anhydrous rock, was thought to represent the dry metamorphism of gabbroic or basaltic protoliths under low or moderate pressures. Amphibolite, on the other hand, would have resulted from wet metamorphism under the same P–T conditions (e.g. Yoder, 1955; Fry and Fyfe, 1969, 1971; Bryhni et al., 1970; Ghent and Coleman, 1973; De Wit and Strong, 1975). This hypothesis was abandoned when experimental studies (e.g. Ringwood and Green, 1966; Green and Ringwood, 1967a, 1972) demonstrated that eclogite parageneses are restricted to high pressures. Other studies (e.g. Essene et al., 1970; Holland, 1979) also revealed that eclogite stability is not restricted to low water pressures, although the eclogite-amphibolite transition is naturally sensitive to PH2 O (see Carswell, 1990a). Meanwhile, progress in crystallography had revealed the true essence of an eclogite. The behaviour of some cations in crystals, particularly Al, accounted well for the high density of eclogite parageneses (Wickman, 1943; Fairbairn, 1943; Thompson, 1947; White, 1964; Smith, 1982). Because of their relatively large size, Al cations are not stable at high P in tetrahedral sites, which are compressed as pressure increases. Therefore, high pressure, and to a lesser extent low temperature, favours Al in sixfold-coordination (i.e. AlVI), which is the case of eclogite minerals, whereas low pressure favours minerals with Al in tetrahedral sites (i.e. AlIV). The well-known univariant reaction 1 albite!1 jadeite+1 quartz, for instance, can be simply written as 1 AlIV!1 AlVI. At much higher pressure, Si is in turn expelled from the tetrahedral sites, forming minerals such as majoritic garnets (e.g. Ringwood, 1970; Ringwood and Major, 1971) and stishovite (e.g. Stishov and Popova, 1961; Stishov, 1962). 176 G. Godard / Journal of Geodynamics 32 (2001) 165–203 After confirmation by experimental work, eclogite was definitely considered a high-pressure metamorphic rock of deep origin. The invention and development of the solid-media apparatus (e.g. Yoder, 1950; Boyd and England, 1960a) and the diamond-anvil cell (Coes, 1953; Weir et al., 1959) led to great progress in high-P-T experimental petrology, the main stages of which were highP synthesis of diamond (Bundy et al., 1955), study of the quartz-coesite transition (Coes, 1953; Boyd and England, 1960b), determination of the stability fields for Al2SiO5 polymorphs (Khitarov et al., 1963; Bell, 1963; Althaus, 1967), investigation of the gabbro–eclogite transition (Ringwood and Green, 1966; Green and Ringwood, 1967a, 1972: (Fig. 6), and the study of the albite=jadeite+quarz univariant reaction (see: Yoder, 1950; Newton and Smith, 1967; Holland, 1980). Since the 1970s, use of equilibrium thermodynamics has allowed the application of these new and abundant experimental data to natural eclogite parageneses (see Carswell and Harley, 1990). The stability of the omphacite solid solution (e.g. Kushiro, 1969; Holland, 1983, 1990) and the use of geothermometers based on (Fe, Mg)-exchange between garnet and clinopyroxene (e.g. Råheim and Green, 1975), among others, led to the determination of P–T paths for many eclogites worldwide. The estimates of P–T conditions for the eclogite parageneses were generally P>1.4 GPa at T=500–800  C. Estimated pressures have greatly increased in comparison to early estimates that hardly ever attained 1 GPa. Finally, in recent years, the discovery of coesite-bearing crustal rocks (Chopin, 1984, 1987; Smith, 1984; see Section 3.4) has raised the upper pressure limit of the eclogite facies to more than 4 GPa. During the two last decades, there has also been a tremendous advance in other fields of eclogite studies: geochronology (see Gebauer, 1990), petrofabric analysis and plastic deformation mechanisms (see Godard and Van Roermund, 1995), the role of kinetics (see Rubie, 1990) and behaviour and recycling of fluids during subduction (e.g. Ahrens and Schubert, 1975; Philippot, 1993; Philippot and Rumble, 2000). Since 1982, an International Eclogite Conference takes place every 4 years. Several books have been published (e.g. Smith, 1988a; Carswell, 1990b; Coleman and Wang, 1995), as well as hundreds of monographs and articles (Fig. 7), indicating that there is more interest in eclogite than ever before. 3. Geodynamic interpretations While our knowledge of eclogite improved, several hypotheses, sometimes confused and embroiled in controversies, have been put forward to interpret eclogite and eclogite-facies rocks in terms of geodynamics. We present here some of these hypotheses and controversies. The reader should be aware, however, that the most recent of them, still under debate, are too close for a proper historical perspective. During the two last centuries, the survey of eclogite occurrences, first in Europe and then worldwide, has revealed that there are ‘‘eclogites and eclogites’’. Several eclogite classifications were proposed (e.g. Eskola, 1921, 1939; Smulikowski, 1964a; Coleman et al., 1965; Banno, 1970), in which eclogites were discriminated on the basis of their mode of occurrence, mineral and bulk compositions, and geodynamic setting. The classifications of Smulikowski (1964a) and Coleman et al. (1965) are somewhat similar and have proved to be useful. They are still occasionally used. The three eclogite groups proposed by these authors are very different in terms of geodynamics, giving rise to specific hypotheses and, therefore, we present them separately. G. Godard / Journal of Geodynamics 32 (2001) 165–203 177 (a) Eclogites from the mantle (i.e. group I of Smulikowski and group A of Coleman et al.). These eclogites are associated with ultrabasic rocks, either in peridotite bodies or as xenoliths in kimberlite pipes. They were involved in the ‘‘eclogite layer’’ controversy presented in Section 3.1. Moreover, their origin (mantle melt or subducted oceanic crust) is still debated. (b) Ophiolitic eclogites (i.e. group II of Smulikowski and group C of Coleman et al.). They are associated with glaucophanites and, with them, form high-pressure belts in orogens. Since the outset of plate tectonics, they have been considered as remnants of paleo-subduction zones (Section 3.2). (c) Eclogites within gneiss (i.e. group III of Smulikowski and group B of Coleman et al.). These eclogites were involved in the ‘‘in situ versus foreign’’ controversy (Section 3.3) and in the still unresolved enigma of ultrahigh-pressure metamorphism (Section 3.4). 3.1. Mantle eclogites and the so-called ‘‘eclogite layer’’ The historical background of the study of mantle eclogites is closely connected to that of kimberlites. Since a historical review of kimberlites, however, is beyond the scope of this paper, we only recall here the principal stages of this history (see also: Boutan, 1886; Lewis, 1897; Julien, 1909; Wagner, 1914; Williams, 1932; Bardet, 1973–1977; Meyer, 1979). Diamonds have been mined in South Africa since 1867, either in placers or in ‘‘blue grounds’’, to which Lewis gave the name ‘‘kimberlite’’ (Lewis, 1897, p. 50). Cohen (1872), Moulle (1885) and Lewis (1887) interpreted these ‘‘blue grounds’’ as volcanic pipes. Similar kimberlite pipes were also discovered in the USA (see Bonney in Lewis, 1897; e.g. McGetchin and Silver, 1972), Rhodesia (Mennell, 1910), Australia (e.g. Card, 1902), Tanganyika (e.g. Williams, 1932) and Siberia (e.g. Moor, 1941; Leontev and Kadensky, 1957). Cohen (1879) recognized eclogite together with peridotite among the nodules of the diamond-bearing breccia of Jagersfontein, in South Africa. Because of his discovery of diamond in eclogite nodules from a kimberlite, Bonney (1899, 1899–1900, 1900) identified eclogite as being the parental rock of diamond. Meanwhile, the origin of eclogite nodules was debated. Some petrographers saw in them segregations from the kimberlite magma, whereas others interpreted them as fragments derived from some formation of eclogite existing at a great depth (see: Bonney, 1899–1900, 1907; Wagner, 1914). This latter hypothesis was supported by the new idea that eclogite and diamond were the high-pressure equivalents of, respectively, gabbro (see Section 2.4) and graphite (Moissan, 1893, 1894; Bakhuis-Roozeboom, 1901; see Bundy et al., 1955). Kimberlite studies favoured the idea that eclogite could be abundant in the interior of the Earth. In 1912, L. L. Fermor, geologist of the Geological Survey of India (see: Krishnan, 1954; West, 1989), used the volume law to predict the existence of a dense eclogite-bearing ‘‘infra-plutonic zone’’ (i.e. the mantle) lying beneath a ‘‘plutonic zone’’ (i.e. the crust) and extending downwards ‘‘as far as the presumed metallic core of the earth’’ (Fermor, 1912, 1913; see note 3 in the Appendix). He proposed that a sharp transition in rock densities due to the gabbro-to-eclogite transition might occur between the plutonic and infra-plutonic zones. In his opinion, such a transition might well agree with the principle of isostasy, and could be the source of basaltic magmas (Fermor, 1914). Fermor’s hypothesis was at the origin of the ‘‘eclogite layer’’ theory, which, at first sight, was confirmed by the existence of eclogite xenoliths in kimberlite pipes and by the well-known 178 G. Godard / Journal of Geodynamics 32 (2001) 165–203 ‘‘Moho’’ discontinuity, discovered by the Croatian seismologist Andrija Mohorovičić in 1910 (Mohorovičić, 1910; see Grau, 1977). Eskola accepted and developed the theory together with his friend Goldschmidt in Oslo (Eskola, 1921, 1936; Goldschmidt, 1922; see Buddington, 1943). On the basis of seismological data, Goldschmidt (1922) postulated an eclogite layer with a density of 3.4–4.0 located between 120 and 1200 km beneath the surface. In 1921, Eskola went to the Geophysical Laboratory in Washington to test the theory by synthesizing minerals at high pressures. The experiments failed, however, but the eclogite theory aroused lively discussion, and became supported by researchers such as Holmes (1926) and Wagner (see: Marmo, 1965). Other petrologists, for the most part Backlund (1936) and Korzhinskii (1940), disapproved of the concept, considering eclogite as being merely a rare crustal rock rather than derived from the mantle (see Section 2.4). The existence of an eclogite layer in the upper mantle was still envisaged as late as 1971 (e.g. Birch, 1952; Lovering, 1958; Kennedy, 1959; Carr, 1966; Ito and Kennedy, 1970; Sobolev and Sobolev, 1971; Tarkov et al., 1971), although rejected by several authors who preferred the ‘‘peridotite’’ hypothesis (e.g. Verhoogen, 1954; Kuno, 1959; Harris and Rowell, 1960; Ringwood, 1962; Sheynmann, 1963; Harris et al., 1967; see: Wyllie, 1965, 1970; Stegena, 1966; Kuno, 1967; Bott, 1971). The first group of authors regarded the Mohorovičić discontinuity as a phase transition (i.e. basalt or gabbro to eclogite), whereas the latter supported the existence of a chemical discontinuity (i.e. basaltic or sialic crust to peridotite). The eclogite-layer hypothesis was apparently supported by seismological data and considerations on isostasy, which predicted physical properties for the upper mantle (density=3.3 g/ cm3; VP=8.1 km/s) that seemed compatible with eclogite. The supporters of the eclogite layer assumed that the Earth’s temperature increases with depth a little more slowly under the oceans than under the continents, explaining the varying depths to the Mohorovičić discontinuity—i.e. to the gabbro–eclogite transition—under the oceans and continents (e.g. Kennedy, 1959). The hypothesis was abandoned after the first experimental investigations on the gabbro-toeclogite transition, which were performed mainly by Green and Ringwood (Kushiro and Yoder, 1964; Ringwood and Green, 1964, 1966; Green, 1967; Green and Ringwood, 1967a, 1972; see Green, 1998). These studies demonstrated that (a) the transition was not sharp (Fig. 6), unlike the Mohorovičić discontinuity, and (b) was too deep to coincide with the discontinuity under the oceans. The alternative hypothesis was a fertile peridotitic upper mantle with the capacity to yield basalt by partial melting and whose model composition was termed ‘‘pyrolite’’ (e.g. Ringwood, 1962; Green and Ringwood, 1963, 1967b; see Green, 1998). The peridotite hypothesis was definitely accepted when, around 1971, peridotite massifs in thrust ophiolites were identified as being fragments of the upper mantle (e.g. Davies, 1971; Bezzi and Piccardo, 1971; see Section 3.2). Indeed, eclogite xenoliths from kimberlites do exist and demonstrate the presence of eclogite in the mantle, though as a minor constituent. The origin of these mantle eclogites has been a matter of debate during the three last decades. While some authors proposed an origin as mantle cumulates or melts, others postulated models for an origin as subducted oceanic crust (see e.g. Schulze and Helmstaedt, 1988; Dawson and Carswell, 1990, pp. 344–348). This question is still debated nowadays. Possibly, eclogites of both origins exist. 3.2. Ophiolitic eclogites: a record of subduction Around 1970, the discussion on eclogite left the so-called eclogite layer to focus on subduction zones where, according to the new theory of plate tectonics, oceanic lithosphere was subducted. In a G. Godard / Journal of Geodynamics 32 (2001) 165–203 179 Fig. 6. ‘‘Diagrammatic representation of the change of mineralogy with change of pressure at 1100  C in the quartz tholeiite composition’’ (from Green and Ringwood, 1967a). The gabbro-to-eclogite transition was investigated experimentally by Green and Ringwood in 1966–1967. The results showed that the transition is progressive and occurs at high-pressure conditions (see text). Fig. 7. Frequency histogram of references on eclogite in the geological literature. Vertical axis: yearly frequency of the word ‘‘eclogite’’ (or any related words) in the title of geological references. Source: Georef database (# SilverPlatter). A: beginning of plate tectonics; B: first discovery of coesite-bearing crustal rocks. 180 G. Godard / Journal of Geodynamics 32 (2001) 165–203 very few years, there was a complete renewal of hypotheses on Alpine-type glaucophane-bearing high-pressure belts, which came to be considered as relics of partly subducted oceanic crust. It is again to de Saussure (1779–1796) that we owe the first description of glaucophanites. On the 20 August 1792, he visited the famous glaucophanite occurrence of Saint-Marcel (Aosta Valley, Italian Alps). He described the rock as composed of ‘‘schorl bleuâtre’’ (bluish schorl) and garnet (see note 2 in the Appendix). Much later, blueschists were also described in Greece by Hausmann (1845), who created the name glaucophane (from glaukó& [bluish] and jaino [to appear]). Strüver (1875), on the other hand, chose the name ‘‘gastaldite’’ for a similar blue amphibole of the Alps and this last name was used by Italian geologists until around 1900. Glaucophane-bearing rocks have been described in Greece (Hausmann, 1845; Lüdecke, 1876; Lepsius, 1893), in New-Caledonia (Jannettaz, 1867; Lacroix, 1941), the Alps (Strüver, 1875; Bonney, 1879, 1886; Cossa, 1880; Termier, 1891; Franchi, 1895, 1902b; Piolti, 1902; Zambonini, 1906; Dal Piaz, 1928), on the Île de Groix in France (Barrois, 1883; Lasaulx, 1883, 1884), Japan (Koto, 1887; Suzuki, 1924), Indonesia (Retgers, 1891), California (Palache, 1894; Ransome, 1894; Smith, 1906; Borg, 1956), and Venezuela (Dengo, 1950; Schürmann, 1950). Peculiar dense minerals such as lawsonite were considered typical of blueschists (e.g. Ransome, 1895; Franchi, 1897). Commonly, these glaucophanites were associated with ultramafites and glaucophane-bearing eclogites (e.g. Cossa, 1880; Piolti, 1902; Franchi, 1902b; Holway, 1904; Weinschenk, 1904; Smith, 1906; Dal Piaz, 1928). Furthermore, transitions to unmetamorphosed gabbro or basalt were observed (e.g. Bonney, 1879; Koto, 1887; Lepsius, 1893; Franchi, 1895; Holway, 1904; Smith, 1906; Zambonini, 1906; Lacroix, 1941; Bearth, 1959, 1970; Coleman and Lee, 1963). Consequently, blueschist terrains clearly appeared as metamorphosed ‘‘ophiolites’’. The modern concept of ophiolite results from a long and confused evolution. Alexandre Brongniart created the name in 1827 to describe serpentinites. It was derived from the Greek 0ji& meaning snake, with reference to serpentine pseudomorphs after olivine, a structure that resembles the skin of a snake. It was first applied as an alternative for serpentinite, a name which is itself derived from the Latin ‘‘serpens’’ (snake) for the same reason. Steinmann (1927) elevated ophiolite from a rock term to a rock association of serpentinised peridotites, gabbros and dolerites (see: Coleman, 1977b; Green, 1971). This ‘‘Steinmann trinity’’ became considered as typical of Alpine-type orogens and was thought to form by the intrusion and eruption of igneous rocks on the floor of a ‘‘geosyncline’’ (e.g. Brunn, 1960, 1961; see Wyllie, 1970). The latter concept of geosyncline had been created by Hall (1859), theorised by Dana (1873) and further developed by Haug (1900) (see: Knopf, 1948; Aubouin, 1965; Schneer, 1997). It foreshadowed the ocean of modern plate tectonics. A geosyncline was a deep marine basin where sediments were deposited and then involved in an orogen. As a weak zone in the crust, it was regarded as the preferred site for tectogenesis and the development of a subsequent orogenic belt. Schürmann (1951–1956) showed that blueschists and eclogites were localized in high-pressure belts, which he interpreted as remnants of ophiolite-bearing geosynclines that had disappeared during tectogenesis. The high-pressure metamorphism of these ophiolites was generally attributed to load metamorphism caused by tectonic burial during thrust faulting (e.g. Blake et al., 1969; Niggli, 1970; Frey et al., 1974). Miyashiro (1961) showed the existence, in the circum-Pacific region, of low-pressure belts arranged parallel to the ophiolite-bearing high-pressure belts. He envisaged that such paired metamorphic belts might correspond respectively to the margin and the centre of a geosyncline. Although the geosyncline theory prefigured in some way modern plate tectonics, the advent of the latter radically modified the interpretation of ophiolite and blueschist terrains. Gass (1968) G. Godard / Journal of Geodynamics 32 (2001) 165–203 181 proposed that ophiolites were fragments of the ocean floor. Soon afterwards, Moores and Vine (1971) regarded them as representing an ancient oceanic crust. Thus, ‘‘geosynclines’’ became ‘‘ocean basins’’. Furthermore, the sea-floor spreading theory, conceived in the 1960s by, among others, Dietz (1961), Hess (1962, 1965), Vine and Matthews (1963), Hurley (1968) and Le Pichon (1968), had the subduction of oceanic crust as a necessary corollary (Wilson, 1965). The term ‘‘subduction’’, from sub- [under] and ducere [to pull], was introduced as early as 1951 by André Amstutz to designate the abrupt descent of a segment of lithosphere. After the ‘‘Penrose Conference’’ of December 1969, it came to be used as a plate tectonic concept (White et al., 1970; see: Dickinson, 1970; Lanterno, 1982). The subduction of oceanic lithosphere was also in agreement with the seismic zones that Wadati (1935) and Benioff (1954, 1955) had already defined. Subduction of an oceanic crust to depths should logically produce eclogite. Very surprisingly, Arthur Holmes, a professor of geology at the University of Durham (England), had already imagined a close hypothesis as early as 1931. In an article entitled ‘‘Radioactivity and Earth movements’’, Holmes (1931) invoked convection currents in the substratum of the continents to explain continental drift (Fig. 8; see note 4 in the Appendix). Because of the radioactivity, the temperature should be higher beneath the continents than under the ocean. Therefore, currents would rise under continents, spread horizontally, and move downward under oceans in ‘‘subsidence’’ zones where eclogite would form, resulting from ‘‘directional pressure’’ (see note 4). Being heavy, the eclogite is carried down and thus contributes to the convection. On the other hand, Holmes did not understand the rifting process [see Fig. 8(c)]. This hypothesis of eclogite formation was ignored at the time. The supporters of Alfred Wegener’s theory did not understand the implications of Holmes’s convection currents on the continental drift theory (see Gohau, 1991). Indeed, the idea that oceanic crust can be transformed into eclogite in subduction zones emerged during the years 1970–1975 and, naturally, high-pressure belts came to be considered as metamorphosed oceanic lithosphere (e.g. Coleman, 1971, 1977a,b; Ernst, 1971, 1975a,b; Fry and Fyfe, 1971; Maresh, 1972; Miyashiro, 1972, 1973; Nagle, 1974; Platt, 1975; Råheim and Green, 1975; Erdmer and Helmstaedt, 1983). The paired metamorphic belts of Miyashiro (1961) were reinterpreted in the light of the new subduction zone model (e.g. Oxburgh and Turcotte, 1970) as resulting from the contrasted thermal gradients between the cold subducting oceanic slab and the edge of the island arc (e.g. Miyashiro, 1967, 1972, 1973; Ernst et al., 1970). The high-temperature retrogression of many high-pressure belts—i.e. a clockwise P–T path—was explained by a return to a more normal geothermal gradient once subduction had stopped (e.g. Ernst et al., 1970). Furthermore, Green and Ringwood (1968) demonstrated that partial melting of eclogite could give rise to the calc-alkaline magma series occurring in island arcs above subduction zones. The last piece of the puzzle to fall into place was the emplacement mechanisms for high-pressure terrains during tectogenesis, i.e. continental collision (e.g. Laubscher, 1969) or obduction (e.g. Coleman, 1971, 1977a,b). Within 10 years, plate tectonics had radically modified our understanding of high-pressure belts. 3.3. Eclogites enclosed within gneisses: ‘‘in-situ versus foreign’’ controversy Because the model of oceanic crust subduction proved successful and fruitful in the case of Alpine-type blueschist terrains, many authors, including myself, tried to apply the model to eclogites enclosed within gneisses in ancient orogens. Subduction, continental collision and obduction were the master keywords in the literature on eclogites during the 1980s (see: Kienast, 182 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Fig. 8. Holmes’s hypothesis for eclogite formation (Holmes, 1931). This hypothesis foreshadows the modern concept of subduction zone. (a): ‘‘Sub-continental circulation. Upper or sial layer, dotted. Intermediate layer (amphibolite, gabbro, etc.) line-shaded. Substratum, unshaded.’’ (b): ‘‘Distension of the continent on each side of A leaving an island or swell in the dead area above A. Above B and C eclogite formation results from the crystallisation of the material of the intermediate layer, and oceanic deeps are produced. The front part of the sial is thickened and a borderland results. Behing this, one effect of the heat transport from A to B or from A to C is the development in each case of a geosyncline.’’ Crosses in c and b represent sinking blocks of eclogite. (c): ‘‘Illustrating the formation of a rift valley by subsidence of the sial over the belt of eclogite formation.’’. 1983; Godard, 1988; O’Brien et al., 1990; Schmädicke, 1994). Even small and isolated eclogite boudins were often thought to derive from an ocean. This hypothesis was supported since the 1970s by geochemical studies indicating that some of these eclogites have geochemical features of Mid Ocean Ridge Basalts (e.g. Montigny and Allègre, 1974). Moreover, many eclogites revealed an early P–T history apparently different from their surrounding gneiss, and this could be interpreted as resulting from the accretion of an eclogitised oceanic crust during continental collision. As a matter of fact, the major problem concerning these eclogites was their relationship with the surrounding gneisses, which frequently do not show any evidence of eclogite-facies metamorphism. Several solutions have been proposed to explain this inconsistency: rejection of the high-pressure conditions of formation for the eclogites (see Section 2.4); formation of the eclogites at mantle-depths and subsequent emplacement in their surrounding gneiss during a plastic deformational event; formation of the eclogites in situ in their present host gneisses, followed by a late obliteration of the eclogite-facies parageneses in the surrounding gneiss. The debate evolved into a controversy, which mainly concerned the eclogites of Norway (‘‘in situ versus foreign origin’’: see Smith, 1988b, pp. 8–11; Schmädicke, 1994). Although not completely solved, the problem is less topical nowadays. G. Godard / Journal of Geodynamics 32 (2001) 165–203 183 A careful examination of the gneiss has shown that eclogite-facies relics do exist in some of these rocks. There is now a tendency to consider that eclogite-facies parageneses are much more easily preserved in eclogite than in gneiss, where the combined effects of fluids, plasticity and kinetics lead to recrystallisation during retrogression (e.g. Rubie, 1990; Schmädicke, 1994). The origin of eclogites enclosed within gneisses of ancient orogens is still obscure. Several hypotheses are generally envisaged: subduction of oceanic crust subsequently incorporated into orogenic belts during continental collision, high-pressure metamorphism of a sialic crust or, even, tectonic emplacement of mantle eclogites into the crust, together with peridotites. Furthermore, the problem has been further confused by the recent question of ultrahigh-pressure metamorphism. 3.4. Ultrahigh-pressure metamorphism: still enigmatic Chopin (1984) described coesite inclusions and quartz pseudomorphs after coesite in garnet crystals of a pyrope quartzite from Dora–Maira (Italian Western Alps; Fig. 9). The ultrahighpressure polymorph of silica now known as coesite was first synthetized by Coes (1953). It was then discovered in kimberlite eclogites (Smyth and Hatton, 1977), but its presence in such diamond-bearing mantle rocks, though interesting, was not surprising. Discoveries of coesite in crustal rocks, on the other hand, drastically changed petrologists’ ideas about the limits of crustal metamorphism. The scale of metamorphic pressure, all suddenly, reached 5 GPa. The discovery of coesite by Chopin (1984) was nevertheless preceded by similar but more disputable discoveries. Chesnokov and Popov (1965) had already identified coesite pseudomorphs in eclogites from the south Ural Mountains. Knauer and Matthes (1970) also observed aggregates of radiating graphite in the Wessenstein eclogite (Bavaria). From their description, we can assert that these inclusions were probably pseudomorphs after diamond. Finally, Lappin and Smith (1981) proposed pressures as high as 3 GPa for eclogites of the Selje district in Norway. Unfortunately, these early discoveries remained ignored, perhaps because two of them were not published in English, but also because scientists were probably not ready to hear about ultrahigh-pressure metamorphism. After Chopin (1984, 1987), other petrologists reported coesite or pseudomorphs after coesite in eclogites and eclogite-facies rocks. Sobolev and Shatsky (1986), Schreyer (1988), Coleman and Wang (1995), Chopin and Sobolev (1995) have given detailed historical accounts of these discoveries. Therefore, we only mention them here briefly. Coesite or quartz pseudomorphs after coesite have been reported from the Alps (Chopin, 1984, 1987; Reinecke, 1991), Norway (Smith, 1984), Dabieshan and ‘‘Su-Lu’’ in eastern China (Yang and Smith, 1989; Okay et al., 1989; Wang et al., 1989, 1993; Enami and Zang, 1990; Hirajima et al., 1990; Brunel et al., 1991; Okay, 1993; etc., see Wang et al., 1995), Kazakhstan (Tagiri and Bakirov, 1990), Urals (Chesnokov and Popov, 1965; Lennykh et al., 1995), Saxony and Sudetes in Europe (Schmädicke, 1991; Bakun-Czubarow, 1991), and Mali (Caby, 1994). New high-pressure minerals were discovered (ellenbergerite, Mgcarpholite. . .). More surprisingly, microdiamond inclusions or graphite pseudomorphs after diamond have also been discovered in Morocco (Beni Bousera peridotite massif: Pearson et al., 1989), Russia (gneiss of the Kokchetav massif: Sobolev and Shatsky, 1987, 1990), eastern China (Dabieshan eclogite: Xu et al., 1991; Zhang et al., 1991), Norway (gneiss on Fjörtoft island: Dobrzhinetskaya et al., 1993, 1995; see Smith, 1995) and Saxony (gneiss in the Erzgebirge: Nasdala and Massonne, 2000). Haggerty and Sautter (1990) presented petrological evidence for an ultradeep (>300 km) origin of some ultramafic xenoliths from kimberlites, corresponding to depths as low 184 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Fig. 9. The first coesite inclusion discovered in a crustal rock by Christian Chopin in 1984 (# Ch. Chopin). Coesite inclusions are surrounded by a quartz corona that developed during retrogression. The increase of volume due to the coesite!quartz transition produced radiating fractures in the host garnet. This observation, together with similar subsequent discoveries, was at the origin of the concept of ultrahigh-pressure metamorphism. 0.9 cm on the photo = 0.1 mm (i.e. width of the photo = 1.185 mm). as the mantle transition zone. Surprisingly, several authors (e.g. Yang et al., 1993; Dobrzhinetskaya et al., 1996; Van Roermund et al., 2000) also presented similar evidence for garnet peridotites enclosed in gneisses, but this is still a matter of debate (see arguments for and against in Green et al., 2000, and Trommsdorff et al., 2000, respectively). Ultrahigh-pressure metamorphism has been a matter of considerable interest and debate during the last two decades. Currently, the problem is not so much the recognition of the reality of ultrahighpressure metamorphism as the geodynamic mechanisms that could explain how such deep rocks have been incorporated into the sialic crust and exhumed to the surface. The explanations advocated in the literature range from overpressure (see Smith, 1995, pp. 336–341) to exhumation favoured by erosion or tectonic thinning after continental collision (see Platt, 1993; Hacker and Peacock, 1995). Subduction down to depths of 250 km and subsequent exhumation of continental material have been confirmed by numerical models (e.g. Shemenda et al., 1996; Ranalli et al., 2000). However, the problem is far from being solved and will certainly remain an enigma for some time to come. 4. Conclusion Eclogite is an example of a rock that has proved to have a kind of destiny in the history of the geological sciences. As we have seen, it has been at the origin of major concepts and developments in endogenous petrology (Section 2), and has been involved in many geodynamic hypotheses (Section 3). The fundamental reason for this particularity may be linked to the hybrid nature of this G. Godard / Journal of Geodynamics 32 (2001) 165–203 185 rock, which is crustal by its composition and origin, but already belongs to the mantle because of the deep structural level where it is formed. Whatever the reasons, eclogite studies over two centuries have produced numerous questions, hypotheses, theories and controversies, which all together have been exceptionally fruitful. They represent a nice example of the relevance and efficiency of the inductive method in science, which is based on the accurate observation of facts. Acknowledgements G. Dal Piaz, G. Gohau, E. Lanterno, A. Mottana, A. Perchuk, G. Ranalli and D.C. Smith are thanked for their helpful comments. G. Gohau drew my attention to Holmes’s convection-current hypothesis. The article ‘‘Timetable of Petrology’’ (Yoder, 1993) also provided helpful information. M.S.N. Carpenter edited the English style. D. Decrouez, E. Lanterno and P.-A. Proz have facilitated the access to Saussure’s collection in Geneva. P.-J. Chiappero did likewise for Haüy’s collection in Paris. Thanks are also due to N. Accardi, Ch. Chopin, J. Justin and P. Karhunen for having provided some of the photographs. Appendix Note 1: Creation of the name ‘‘eclogite’’ by René-Just Haüy (1822). Eclogite samples in Haüy’s collection Note 1a: Haüy (1822), vol. 2, p. 456: ‘‘Dans la première [de trois roches primitives], la diallage est considérée comme faisant fonction de base, et forme avec le grenat une combinaison binaire à laquelle sont censés s’unir accidentellement le disthène, le quarz, l’épidote et l’amphibole laminaire. J’ai donné à cette roche le nom d’éclogite, qui signifie choix, élection parce que ses composans, n’étant pas de ceux qui existent communément plusieurs ensemble dans les roches primitives, comme le feldspath, le mica, l’amphibole, semblent s’être choisis pour faire bande à part. Cette roche se trouve en Carinthie, dans le Sau-Alpe, et en Styrie.’’ Haüy (1822), vol. 4, pp. 548–549: ‘‘Eclogite (*). Diallage verte et grenat. Composans accidentels: disthène, quarz, epidote blanc vitreux, amphibole laminaire, fer sulfuré magnétique. [. . .] (*) d’eklogZ , choix, parce que les composans de cette roche n’étant pas de ceux qui existent plusieurs ensemble dans les roches primitives, tels le feldspath, le mica, etc., semblent s’être choisis pour faire bande à part.’’ Note 1b: Haüy’s collection of rocks still exists at the Galerie de Minéralogie, Muséum National d’Histoire Naturelle, in Paris. It contains 7 samples that are labelled éclogite (505, 506, 509–513). All originate from ‘‘Pays de Bayreuth’’ (Bavaria). 505 and 506 are from ‘‘Hoff’’; 510 originates from Gefrees, near Münchberg. All are definitely eclogites except 513, which contains too much feldspar to deserve the name eclogite. The collection catalogue mentions a few other eclogite samples that are now missing: 507, 508 (from Carinthia), 514, 517. 186 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Note 2: Eclogite, eclogite micaschist and glaucophanite samples in Saussure’s collection (18th century) De Saussure’s collection can be seen at the Muséum d’Histoire Naturelle de Genève, in Switzerland (see Lanterno, 1976). Each of the samples are arranged in a box, with a reference to the section in Voyages dans les Alpes (Saussure, 1779–1796), where the rock is described. Unfortunately, some disarrangement has occurred since 1779, and these references are not always correct. We list below those samples that we have identified as being eclogite, eclogite micaschist or glaucophanite (# refers to the sample number in the collection, and x to the section in Voyages dans les Alpes). Note that de Saussure called ‘‘schorl’’ any kind of dark or greenish mineral with prismatic habits, such as amphibole, pyroxene and tourmaline. #41392, 41393 (x194 [doubtful; possibly x145]): pebbles composed of a beautiful eclogite, Rhone valley near Geneva (‘‘roche grenatique prise dans les environs de Genève’’). #41526, 41527, 41530 (x647, x649): amphibolitised eclogite with kelyphite coronae, Le Brévent, Haute-Savoie, France (‘‘Je trouvai cependant sur la cime [du Brévent] une roche composée de schorl noir en aiguilles, de quartz & de grenats [dont la] forme étoit exactement rhomboı¨dale’’). #41790 (x965): retrogressed and foliated eclogite, with an ‘‘eclogite micaschist’’ layer, Montjovet, Aosta Valley, Italy (‘‘[along the road near Mont-Jovet,] alternatives continuelles de stéatites, de roches de corne, de schorl, de grenats & d’une roche mélangée de quartz, de mica & de pierre calcaire’’). #41791, 41793 (x965, x966): beautiful layered and light-coloured eclogite, Montjovet, Aosta Valley, Italy (‘‘[along the road near Mont-Jovet,] on rencontre des rochers composés d’un mélange de schorl verd foncé en aiguilles brillantes & de grenats rouges en masse ou confusément crystallisé’’). #41795 (x966): retrogressed eclogite, Montjovet, Aosta Valley, Italy (‘‘roche schisteuse grenatifère’’). #42560 (x2282): amphibole-rich light-coloured rutile-bearing eclogite, Mont-Cervin, Valais, Switzerland (‘‘amphibolite à grenats’’). #42571-42573 (x2293): glaucophanite [# 42572: typical garnet glaucophanite], from Saint-Marcel, Aosta Valley, Italy (‘‘schorl bleuâtre’’). Note 3: The hypothetical eclogite-bearing ‘‘infra-plutonic zone’’, as a consequence of the volume law, by L. L. Fermor (1912) ‘‘[...] I was led to consider various other garnetiferous rocks, such as eclogite, and to arrive at the conclusion that the deeper one goes in the earth’s crust the more abundant must the garnets become, on account both of the increasing pressure and of the increasing temperature, the high temperature inducing the molecular mobility necessary to permit the constituents of pyroxene, olivine, and anorthite, to rearrange themselves as the denser molecule garnet. The conclusion drawn was that below a certain depth all the ferromagnesian minerals, such as pyroxene, amphibole, olivine, and biotite, with anorthite, have rearranged themselves as far as possible into garnets, for thereby the maximum reduction in volume and absorption of heat is effected. G. Godard / Journal of Geodynamics 32 (2001) 165–203 187 At present, petrologists regard the plutonic rocks, such as granite and gabbro, as the most deepseated known rocks. But, under the effects of enormous pressures, the granites should become garnetiferous and the gabbros be converted into eclogites, and the conclusion seems inevitably to follow that beneath the rocks now known as plutonic there must be a zone of garnetiferous rocks extending downwards in a plastic-solid form as far as the presumed metallic core of the earth. For this zone, unless a better term suggests itself, I propose the name infra-plutonic. The characteristic minerals of the infra-plutonic zone will be those that occupy the least volume. The commonest mineral in the basic rocks will be garnet, and the nature of the associated minerals will depend upon the excess constituents left over after the maximum possible number of garnets has been formed. They will be various varieties of pyroxene or olivine, with occasional anorthite feldspar. One other mineral may be specified as characteristic of the basic infra-plutonic rocks, namely diamond, which may be regarded as the molecularly dense form of the graphite occurring in rocks nearer the surface. Normally, the infra-plutonic rocks will not reach the earth’s surface, as their upward passage must in most cases be accompanied by a reduction of pressure whilst the temperature is still high, enabling the garnets to break down, with increase of volume, into less dense minerals such as pyroxene and olivine. Under certain circumstances, however, particularly if a slow reduction in pressure is accompanied by a more rapid reduction of temperature, due to the lowering of the isogeotherms in a given part of the earth’s crust, we may expect the eclogites finally to arrive at the surface; although even then there may often be a partial breaking up of the garnet with the production of the well-known kelyphite rims or reaction borders of some garnetiferous peridotites. It is interesting to note that the original matrix of diamond proves in almost every case to be some form of peridotite or eclogite. For instance, the blue ground of the diamond-bearing pipes of Kimberley is a brecciated mass of altered peridotite and eclogite with scattered diamonds, and these pipes have evidently been filled from great depths below the earth’s crust. It is possible that they have tapped the infra-plutonic zone.’’ Note 4: Formation and sinking of eclogites in ‘‘subsidence’’ zones [i.e. subduction zones], by A. Holmes (1931, pp. 580–583) See Fig. 8. We must [...] consider what will happen at the continental margins, or generally, where two [convection] currents meet and turn downwards. The crust above the zone of contact will be thrown into powerful compression and the amphibolite layer will tend to be thickened by accumulation of material flowing in from two directions. The observed effects of dynamic metamorphism at high temperature and differential pressure on such material lead us to expect that recrystallisation into the high-pressure facies, eclogite, will here take place on a large scale. The change of density from 2.9 or 3.0 to 3.4 or more, combined with the simultaneous operation of isostasy would lead to marked subsidence. Sinking of blocks of eclogite would also be facilitated by stoping promoted by the tongues of basaltic magma that would inevitably be present. Such foundering would effectually speed up the downward current for two reasons: the greater density of the sinking blocks, and the cooling of the substratum material in their vicinity.[. . .] We may notice that [eclogite formation] provides a mechanism for ‘engineering’ continental drift, and at the same time for discharging some of 188 G. Godard / Journal of Geodynamics 32 (2001) 165–203 the excess heat generated in the substratum. Each part of the continental block would be enabled to move forward, partly by the fracturing and foundering of the belt of ocean floor weighed down with eclogite immediately in front, and partly by over-riding the ocean floor along thrust planes lubricated by magmatic injections from below. The hypothesis of eclogite formation is supported by the fact that it provides a reasonable explanation of oceanic deeps. It is consistent with their depths, as judged from the requirements of isostasy, and with their occurrence in front of the active orogenic arcs bordering the Pacific on the Asiatic and Austral-asiatic side. That oceanic deeps are under compression is the opinion of Meinesz. He sees in downward flexure under stress a reason for the local defects of gravity revealed over deeps by his gravity surveys of the oceans. Evidence of the foundering of blocks [of eclogite] is from the nature of the case not easy to find, but it may be forthcoming from the occurrence of deep earthquakes (arising from 100 km or more) off the coast of Japan, and by the signs of volcanic activity that have been detected in the floor of the Tuscarara Deep. The upper or sialic layer of the continental margin will also be thickened by the differential flowage of its levels towards the obstructing ocean floor. Here thickening of the crust and mountain building will occur, and the mountain roots, unable to sink, will begin to fuse and give rise to igneous activity of the Circum-Pacific type with basalt-andesite-rhyolite volcanoes [. . .]. The time taken for a block of eclogite to fuse completely is probably of the order of 50 million years. Thus, sinking blocks should have nearly reached the bottom of the substratum before becoming entirely fluid, and streaks in the ascending currents should therefore be fed with magma much more nearly basaltic in composition than the general body of the substratum. The ascending currents will approach the surface in the region behind the advancing continent, and thus the new ocean floor is likely to receive the whole of the basaltic material available. With ascending currents of such relatively light material, and descending currents made relatively dense by the presence in them of eclogite blocks, the whole circulation will be speeded up while continental drift is in progress [. . .].’’ References Note: the bibliography below comprises the references cited in the text, plus a few other selected contributions that are considered important in the history of eclogite, or in the history of metamorphic petrology. For some modern comprehensive reviews, the reader is referred to: Smith (1988a), Carswell (1990b, pp. 350–392), and Coleman and Wang (1995). Ahrens, Th.J., Schubert, G., 1975. Gabbro-eclogite reaction rate and its geophysical significance. Reviews of Geophysics and Space Physics 13 (2), 383–400. Althaus, E., 1967. The triple point Andalusite-Sillimanite-Kyanite. Contributions to Mineralogy and Petrology 16, 29–44. Amstutz, A., 1951. Sur l’évolution des structures alpines. Archives des Sciences [Genève] 1951 (18 Octobre), 323–329. Arzruni, A., 1883. Neue Beobachtungen am Nephrit und Jadeı̈t. Zeitschrift für Ethnologie XV, 163–190. Aubouin, J., 1965. Geosynclines. Elsevier, Amsterdam. xv–335 p. Backlund, H.G., 1936. Zur genetischen Deutung der Eklogite. Geologische Rundschau 27, 47–61. Bakhuis-Roozeboom, H.W., 1901. Die Heterogenen Gleichgewichte vom Standpunkte der Phasenlehre. Friedrich Vieweg & Sohn, Braunschweig. (4 Vols.). G. Godard / Journal of Geodynamics 32 (2001) 165–203 189 Bakun-Czubarow, N., 1991. On the possibility of occurrence of quartz pseudomorphs after coesite in the eclogite-granulite rock series of the Zlote Mountains in the Sudetes (SW Poland). Archiwum Mineralogiczne 47, 5–16. + pl. i–ii. Banno, S., 1970. Classification of eclogites in terms of physical conditions of their origin. Physics of the Earth and planetary Interiors 3, 405–421. Bardet, M.G., 1973–1977. Géologie du Diamant. Mémoires du Bureau de Recherches Géologiques et Minières 83, 3 vol., 235+229+169 p. Barrois, Ch., 1883. Sur les amphibolites à glaucophane de l’ı̂le de Groix. Bulletin de la Société minéralogique de France VI, 289–293. Barrow, G., 1893. On an intrusion of muscovite-biotite gneiss in the S. E. Highlands of Scotland. Quarterly Journal of the Geological Society of London 49, 330–356. Bearth, P., 1959. Über Eklogite, Glaukophanschiefer und metamorphe Pillowlaven. Scheiwzerische mineralogische und petrographische Mitteilungen 39, 267–286. Bearth, P., 1970. Zur Eklogitbildung in den Westalpen. Fortschritte der Mineralogie 47, 27–33. Becke, F., 1882. Die Gneissformation des niederösterreichischen Waldviertels. Mineralogische und petrographische Mittheilungen 4, 285–408. Becke, F., 1903. Über Mineralbestand und Struktur der kristallinischen Schiefer. Denkschriften der k. Akademie der Wissenschaften. Mathematisch-Naturwissenschaftliche Klasse LXXV, 1–53 (extended German abstract in Congrès géologique international. Compte rendu de la IX session, Vienne 1903, pp. 553–570). Becke, F., 1921. Zur Facies-Klassifikation der metamorphen Gensteine. Mineralogische und Petrographische Mittheilungen 35, 215–230. Bell, P.M., 1963. Aluminium silicate system: Experimental determination of the triple point. Science 139, 1055–1056. Benioff, H., 1954. Orogenesis and deep crustal structure: additional evidence from seismology. Bulletin of the Geological Society of America 81, 3431–3432. Benioff, H., 1955. Seismic evidence for crustal structure and tectonic activity. Geological Society of America, Special Paper 62, 61–74. Bezzi, A., Piccardo, G.B., 1971. Structural features of the Ligurian ophiolites: petrologic evidence for the ‘‘oceanic’’ floor of the Northern Apennines geosyncline; a contribution to the problem of the alpine-type gabbro-peridotite association. Memorie della Società geologica Italiana 10, 53–63. Birch, F., 1952. Elasticity and constitution of the Earth’s interior. Journal of Geophysical Research 57, 227–286. Bishop, H.R., (Ed.), 1906. Investigations and Studies in Jade. privately printed, New York, 2 Vols. gr. in-f , pl.+ lithographies. Blake Jr., M.C., Irwin, W.P., Coleman, R.G., 1969. Blueschist-facies metamorphism related to regional thrust faulting. Tectonophysics 8, 237–246. Boeke, H.E., 1915. Grundlagen der physikalisch-chemischen. Gebrüder Borntraeger, Berlin x–428 p (398–400). Bonney, T.G., 1879. Notes on some Ligurian and Tuscan serpentines. Geological Magazine (II) VI, 362–371. Bonney, T.G., 1886. On a glaucophane-eclogite from the Val d’Aoste. Mineralogical Magazine VII, 1–8+pl. 1. Bonney, T.G., 1899. The original rock of the south-African diamond. Natural Science, London XV, 173–182. Bonney, T.G., 1899–1900. The parent-rock of the diamond in South Africa (with a reply to a cristicism). Geological Magazine (4), VI, 309–321; VII, 246–248 [+ Proc. Roy. Soc., London, LXV, 1899; Can. Rec. Sci., Montreal, VIII, 1899, 95; Chem. News, London, LXXX, 3, 13; Nature, London, LX, 1901, 620; Kts. Krys. Min., XXXIV, 1901, 433]. Bonney, T.G., 1900. The parent rock of the diamond in South Africa. Proceedings of the Royal Society of London for 1899 LXV, 223–236. Bonney, T.G., 1907. On the supposed kimberlite-magma and eklogite-concretions. Transactions of the Geological Society of South Africa X, 95–100. Borg, I.Y., 1956. Glaucophane schists and eclogites near Healdsburg, California. Bulletin of the Geological Society of America 67, 1563–1583. Bott, M.H.P., 1971. The Interior of the Earth. E. Arnold, London. 316 p. (129–140). Boué, A., around 1820. Essai Géologique sur l’Écosse. Veuve Courcier, Paris, in-8 , x–519 p. Boué, A., 1824. Mémoire géologique sur le sud-ouest de la France, suivi d’observations comparatives sur le nord du même royaume, et en particulier sur les bords du Rhin. Annales des Sciences naturelles 2, 387–423 (415–423); 3, 55– 95, 299–317. 190 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Boutan, E., 1886. Le Diamant. Dunot, Paris, in-8 , 323 p. (bibliography with 375 entries). Boyd, F.R., England, J.L., 1960a. Apparatus for phase-equilibrium measurements at pressures up to 50 kilobars and temperatures up to 1750  C. Journal of Geophysical Research 65, 741–748. Boyd, F.R., England, J.L., 1960b. The quartz-coesite transition. Journal of Geophysical Research 65, 749–756. Brière, Y., 1920. Les éclogites françaises. Leur composition minéralogique et chimique. Leur origine. Bulletin de la Société française de Minéralogie XLIII, 72–222+pl. i-iv; Thèse ès-Sciences naturelles, Sorbonne, 1920, Giard et Brière (Éd.), 143 p.+4 pl. Brøgger, W.C., 1880. Ueber olivinfels von Søndmøre. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1880 (II), 187–192. Brongniart, A., 1827. Classification et caractères minéralogiques des roches homogènes et hétérogènes. Levrault, Paris. 144 p. (94–95). Brunel, M., Kienast, J.R., Matte, Ph., Smith, D.C., Xu, Z., Mattauer, M., 1991. Proterozoic coesite-bearing eclogite from the Dabie Shan, east Qinling Range, central China. Terra Abstracts 3 (1), 85. Brunn, J.H., 1960. Mise en place et différenciation de l’association pluto-volcanique du cortège ophiolitique. Revue de Géographie physique et de Géologie dynamique 3, 115–132. Brunn, J.H., 1961. Les sutures ophiolitiques. Contribution à l’étude des relations entre phénomènes magmatiques et orogéniques. Revue de Géographie physique et de Géologie dynamique 4, 89–96, 181–202. Bryhni, I., Green, D.H., Heier, K.S., Fyfe, W.S., 1970. On the occurrence of eclogite in western Norway. Contributions to Mineralogy and Petrology 26, 12–19. Buddington, A.F., 1943. Some petrological concepts and the interior of the earth. The American Mineralogist 28, 119– 140. Bundy, F.P., Hall, H.T., Strong, H.M., Wentorf, R.H., 1955. Man-made diamonds. Nature 176, 51–55. Caby, R., 1994. Precambrian coesite from northern Mali: first record and implications for plate tectonics in the transSaharan segment of the Pan-African belt. European Journal of Mineralogy 6, 235–244. Card, G.W., 1902. An eclogite-bearing breccia from the Bingera diamond field. Records of the geological Survey of New South Wales VII, 29–39. +pl. ix–xi. Carr, J.B., 1966. Long-term (geotectonic) stress generation, propagation and accumulation in the earth. Nature 210 (5033), 239–245. Carswell, D.A., 1990a. Eclogites and the eclogite facies: definitions and classification. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 1–13. Carswell [ed.], D.A., 1990b. Eclogite Facies Rocks. Blackie, Glasgow and London, 396 p. Carswell, D.A., Harley, S.L., 1990. Mineral barometry and thermometry. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 83–110. Chenevoy, M., 1958. Contribution à l’étude des schistes cristallins de la partie nord-ouest du Massif Central français. Mémoires pour servir à l’explication de la Carte géologique détaillée de la France, 428 p.+2 pl. (246–268). Chesnokov, B.V., Popov, V.A., 1965. Increasing in the volume of quartz grains in South Urals eclogites. Dokaldy of the Academy of Sciences of the U.S.S.R. (English version of Doklady Akademii Nauk SSSR) 162, 176–178. Chopin, Ch., 1984. Coesite and pure pyrope in high-grade blueschists of the Western Alps: a first record and some consequences. Contributions to Mineralogy and Petrology 86, 107–118. Chopin, Ch., 1987. Very-high pressure metamorphism in the Western Alps: implications for subduction of continental crust. Philosophical Transactions of the r. Society of London, Series A 321, 183–197. Chopin, Ch., Sobolev, N.V., 1995. Principal mineralogic indicators of UHP (ultrahigh pressure) in crustal rocks. In: Coleman, R.G., Wang, X. (Eds.), Ultrahigh Pressure Metamorphism. Cambridge University Press, Cambridge, pp. 96–131. Clarke, F.W., Merrill, G.P., 1888. On nephrite and jadeite. Proceedings of the US national Museum XI, 115–130 + pl. xxxiii. Coes Jr., L., 1953. A new dense crystalline silica. Science 118, 131–132. Cohen, E., 1872. Diamant-Vorkommen im Süd-Afrika. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1872, 857–861. Cohen, E., 1879. Über einen Eklogit, welcher als Einschluss in den Diamant-gruben von Jagersfontein, Orange Freistaat, Süd-Afrika, vorkommt. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1879, 864–869. G. Godard / Journal of Geodynamics 32 (2001) 165–203 191 Cohen, E., 1884. Über Jadeit von Thibet. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1884 (I), 71–73. Coleman, R.G., 1971. Plate tectonic emplacement of Upper mantle peridotites along continental edges. Journal of Geophysical Research 76 (5), 1212–1222. Coleman, R.G., 1977a. Emplacement and metamorphism of ophiolites. Ofioliti 2, 41–73. Coleman, R.G., 1977b. Ophiolites: Ancient Oceanic Lithosphere? Springer, Berlin, ix–229 p. Coleman, R.G., Lee, D.E., 1963. Glaucophane-bearing metamorphic rock types of the Cazadero Area, California. Journal of Petrology 4, 260–301. Coleman, R.G., Lee, D.E., Beatty, L.B., Brannock, W.W., 1965. Eclogites and eclogites: their differences and similarities. Geological Society of America Bulletin 76, 483–508. Coleman, R.G., Wang, X. (Eds.), 1995. Ultrahigh pressure metamorphism. Cambridge University Press, Cambridge, 528 p. Compagnoni, R., Dal Piaz, G.V., Hunziker, J.C., Gosso, G., Lombardo, B., Williams, P.F., 1977. The Sesia-Lanzo zone, a slice of continental crust with Alpine high pressure-low temperature assemblages in the western Italian Alps. Rendiconti della Società italiana di Mineralogia e Petrologia 33, 281–334. (‘‘older concepts’’: pp. 289–295). Cossa, A., 1880. Rutil von Gastaldit-Eklogit von Val Tournanche. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1880 (1), 162–164. Dal Piaz, Gb., 1928. Geologia della catena Herbetet-Grivola-Grand Nomenon. Memorie degli Istituti de Geologia della Universita di Padova VII, vii-83 p.+2 pl.+1 map 1/25000. Dal Vesco, E., 1953. Genesi e metamorfosi delle rocce basiche e ultrabasiche nell’ambiente mesozonale dell’orogene pennidico. Schweizerische mineralogische und petrographische Mitteilungen 33, 173–480. (416–428). D’Amico, C., Campana, R., Felice, G., Ghedini, M., 1995. Eclogites and jades as prehistoric implements in Europe. A case of petrology applied to cultural heritage. European Journal of Mineralogy 7, 29–41. Damour, A., 1863. Notice et analyse sur le jade vert. Réunion de cette matière minérale à la famille des wernérites. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) 56, 861–865. Damour, A., 1865. Sur la composition des haches en pierre trouvées dans les monuments celtiques et chez les tribus sauvages. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) 61, 357–368. Damour, A., 1881. Nouvelles analyses sur la jadéite et sur quelques roches sodifères. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) 92, 1312–1318. Dana, J.D., 1873. On some results of the Earth’s contraction from cooling (...). American Journal of Science and Arts 5, 423–443; 6, 6–14, 104–115, 161–172. Dathe, E., 1876. Olivinfels, Serpentine und Eklogite des sächsischen Granulitgebietes. Ein Beitrag zur Petrographie. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1876, 225–249, 337–351 (341–351). DaubréeA., 1859. Études et expériences synthétiques sur le métamorphisme et sur la formation des roches cristallines. Annales des Mines (5) XVI, 155–218, 393–476 (English translation in the Smithsonian Annual Report for 1861, pp. 228–304). Davies, H.L., 1971. Peridotite-gabbro-basalt complex in Eastern Papua: an overthrust plate of oceanic mantle and crust. Bureau of Mineral Resources [of Australia], Geology and Geophysics, Bulletin 128, 1–48. Dawson, J.B., Carswell, D.A., 1990. High-temperature and ultra-high pressure eclogites. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 315–349. Delesse, A., 1857–1861. Étude sur le métamorphisme des roches. Annales des Mines (5) XII, 89–288, 417–516, 705–772; XIII, 321–416; Mémoires présentés par divers savants à l’Académie des Sciences, XVII, 95 p. Dengo, G., 1950. Eclogitic and glaucophane amphibolites in Venezuela. Transactions—American Geophysical Union 31 (6), 873–878. De Wit, M.J., Strong, D.F., 1975. Eclogite-bearing amphibolites from the Appalachian mobile belt, northwest Newfoundland: Dry versus wet metamorphism. Journal of Petrology 83, 609–627. Dietz, R.S., 1961. Continent and ocean basin evolution by spreading of the sea floor. Nature 190, 854–857. Dickinson, W.R., 1970. Global tectonics. Science 168, 1250–1259. Dobrzhinetskaya, L.F., Eide, E.A., Larsen, R.B., Sturt, B.A., Tronnes, R.G., Smith, D.C., Taylor, W.R., 1995. Microdiamond in high-grade metamorphic rocks of the Western Gneiss region, Norway. Geology 23 (7), 597–600. Dobrzhinetskaya, L., Green, H.W., Wang, S., 1996. Alpe Arami: a peridotite massif from depths of more than 300 kilometers. Science 271, 1841–1845. 192 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Dobrzhinetskaya, L., Posukhova, T., Tronnes, R., Korneliussen, A., Sturt, B., 1993. A microdiamond from eclogitegneiss area of Norway. Terra Abstracts 5, 8. Dolomieu, D., an II (1794). Mémoire sur les roches composées en général, et particulièrement sur les pétro-silex, les trapps et les roches de corne, pour servir à la distribution méthodique des produits volcaniques. Journal de Physique, de Chimie, d’Histoire naturelle et des Arts I, 175–200, 241–263 (187–188, 242). Drasche, R. von, 1871. Ueber die mineralogische Zusammensetzung der Eklogite. Mineralogische Mittheilungen 1871 (II), 85–91. Düll, E., 1902. Ueber die Eklogite des Münchberger Gneiss-gebietes. Ein Beitrag zur Kenntnis ihrer genetischen Verhältnisse. Geognostische Jahreshefte XV, 65–156. Ebert, H., 1936. Bemerkung zu den Vorträgen Backlund und Eskola. Geologische Rundschau 27, 74–75. Enami, M., Zang, Q., 1990. Quartz pseudomorphs after coesite in eclogites from Shandong province, east China. American Mineralogist 75, 381–386. Erdmer, Ph., Helmstaedt, H., 1983. Eclogite from central Yukon: a record of subduction at the western margin of ancient North America. Canadian Journal of Earth Sciences 20, 1389–1408. Ernst, W.G., 1971. Metamorphic zonations on presumably subducted lithospheric plates from Japan, California and the Alps. Contributions to Mineralogy and Petrology 34, 43–59. Ernst, W.G., 1975a. Subduction Zone Metamorphism. Dowden, Hutchinson & Ross, Stroudsburg. xiii–445 p.+1 map. Ernst, W.G, 1975b. Metamorphism and Plate Tectonic Regimes. Dowden, Hutchinson & Ross, Stroudsburg. xiii– 440 p. Ernst, W.G., Seki, Y., Onuki, H., Gilbert, M.C., 1970. Comparative study of low-grade metamorphism in the California Coast Ranges and the outer metamorphic belt of Japan. Geological Society of America, Memoir 124, 276 p. Eskola, P., 1915. Om sambandet mellan kemisk och mineralogisk sammansättring hos Orijärvitraktens metamorfa bergarter. Bulletin de la Commission géologique de Finlande 8 (44), 145 p. Eskola, P., 1920. The mineral facies of rocks. Norsk Geologisk Tidsskrift VI, 143–194. Eskola, P., 1921. On the eclogites of Norway. Videnskapsselskapets Skrifter. I- Mathematisk-Naturvidenskapelig Klasse (Kristiana) 1921 (8), 1–118. Eskola, P., 1929. Om mineralfacies. Geologiska Föreningens i Stockholm Förhandlingar 51 (377), 157–172. Eskola, P., 1936. Wie ist die Anordnung der äusseren Erdsphären nach der Dichte zustande gekommen? Geologische Rundschau 27, 61–73. Eskola, P., 1939. Die metamorphen Gesteine. In: Barth, T.F.W., Correns, C.W., Eskola, P. (Eds.), Die Entstehung der Gesteine; Ein Lehrbuch der Petrogenese. Springer, Berlin, pp. 263–407. Essene, E.J., Hensen, B.J., Green, D.H., 1970. Experimental study of amphibolite and eclogite stability. Physics of the Earth and planetary Interiors 3, 378–384. Fairbairn, H.W., 1943. Packing in ionic minerals. Bulletin of the Geological Society of America 54, 1305–1374. (1363– 1365). Favre, A., 1867. Recherches géologiques dans les parties de la Savoie, du Piémont et de la Suisse voisines du MontBlanc. Masson et fils, Paris, 3 Vols.+atlas (I, 100; II, 308, 319–326, 409). Fermor, L.L., 1912. Preliminary note on the origin of meteorites. Journal and Proceedings of the Asiatic Society of Bengal (new ser.) VIII (9), 315–324. (316–317). Fermor, L.L., 1913. Preliminary note on garnet as a geological barometer and on an infra-plutonic zone in the earth’s crust. Records of the Geological Survey of India 43 (1), 41–47. Fermor, L.L., 1914. The relationship of isostasy, earthquakes and vulcanicity to the Earth’s infra-plutonic shell. Geological Magazine (VI) 1, 65–67. Fournet, J., 1841. Mémoire sur la géologie de la partie des Alpes, comprise entre le Valais et l’Oisans. Annales des Sciences physiques et naturelles [. . .] de Lyon IV, 105–183, 483–560 (169—171). Franchi, S., 1895. Noticie sopra alcune metamorfosi di eufotidi e diabasi nelle Alpi occidentali. Bollettino del r. Comitato geologico d’Italia 26, 181–204. Franchi, S., 1897. Sopra alcuni nuovi giacimenti di roccie a lawsonite. Bollettino della Società geologica Italiana XVI, 73–76. Franchi, S., 1900. Sopra alcuni giacimenti di roccie giadeitiche nelle Alpi Occidentali e nell’Apennino ligure. Bollettino del r. Comitato geologico d’Italia 31, 119–158. G. Godard / Journal of Geodynamics 32 (2001) 165–203 193 Franchi, S., 1902a. Ueber Feldspath-Uralitisirung der Natron-Thonerde-Pyroxene aus den eklogitischen Glimmerschiefern der Gebirge von Biella (Graiische Alpen). Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1902 (II), 112–126. Franchi, S., 1902b. Contribuzione allo studio delle roccie a glaucofane e del metamorfismo onde ebbero origine nella regione ligure-alpina occidentale. Bollettino del r. Comitato geologico d’Italia 33, 255–318+pl. viii–ix. Franchi, S., 1904. I giacimenti alpini ed appenninici di roccie giadeitiche e di manufatti di alcune stazioni neolitiche italiane. Atti del Congresso internazionale di scienze storiche sez. IV, Roma, April, 1903 (Vol. V, Archeologia), pp. 357–371. Frey, M., Hunziker, J.C., Frank, W., Bocquet, J., Dal Piaz, G.V., Jäger, E., Niggli, E., 1974. Alpine metamorphism of the Alps. A review. Schweizerische mineralogische und petrographische Mitteilungen 54, 249–290+pl. i–ii. Fry, N., Fyfe, W.S., 1969. Eclogites and water pressure. Contributions to Mineralogy and Petrology 24, 1–6. Fry, N., Fyfe, W.S., 1971. On the significance of the eclogite facies in Alpine metamorphism. Verhandlungen der Geologischen Bundesanstalt (Wien) 2, 257–265. Gass, I.G., 1968. Is the Troodos Massif of Cyprus a fragment of Mesozoic ocean floor? Nature 220, 39–42. Gebauer, D., 1990. Isotopic systems—geochronology of eclogites. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 141–159. Gerichten, E. von, 1874. Ueber der oberfränkische Eklogit. Annalen der Chemie und Pharmacie 171, 183–199. (see also: Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie, 1874, 434–435; Sitzungsberichte der physikalischmedicinischen Societät zu Erlangen, 1874, H. 6, 96–99). Ghent, E.D., Coleman, R.G., 1973. Eclogites from southwestern Oregon. Geological Society of America Bulletin 84, 2471–2488. Ghosh, P.K., 1941. The charnockite series of Bastar state and Western Jeypore. Records of the geological Survey of India LXXV (15), 55–vii p.+8 pl. Godard, G., 1988. Petrology of some eclogites in the Hercynides: the eclogites from the southern Armorican massif, France. In: Smith, D.C. (Ed.), Eclogites and Eclogite-facies Rocks. Elsevier, Amsterdam, pp. 451–519. Godard, G., Martin, S., 2000. Petrogenesis of kelyphites in garnet peridotites: a case study from the Ulten zone, Italian Alps. Journal of Geodynamics 30, 117–145. Godard, G., Van Roermund, H.L.M., 1995. On clinopyroxene strain-induced microfabrics from eclogites. Journal of Structural Geology 17 (10), 1425–1443. Gohau, G., 1991. A History of Geology (revised and translated from the French by A. Carozzi and M. Carozzi). Rutgers University Press, New Brunswick and London. 259 p. Goldschmidt, V.M., 1922. Über die Massenverteilung im Erdinneren, verglichen mit der Struktur gewisser Meteoriten. Die Naturwissenschaften 1922 (42), 918–920. Grau, G., 1977. A short history of ideas concerning the Earth’s crust; a contribution of A. Mohorovičić. Geophysical Prospecting 25 (3), 405–414. Green, D., 1971. Evolution in meaning of certain geological terms. Geological Magazine 108, 177–178. Green, D.H., 1998. About the Academy biographical memoirs Alfred Edward Ringwood 1930–1993. Historical Records of Australian Science 12 (2), 247–266. Green, D.H., Ringwood, A.E., 1963. Mineral assemblages in a model mantle composition. Journal of Geophysical Research 68, 937–945. Green, D.H., Ringwood, A.E., 1967a. An experimental investigation of the gabbro to eclogite transformation and its petrological applications. Geochimica and Cosmochimica Acta 31, 767–833. Green, D.H., Ringwood, A.E., 1967b. The genesis of basaltic magmas. Contributions to Mineralogy and Petrology 15, 103–190. Green, D.H., Ringwood, A.E., 1968. Genesis of calc-alkaline igneous rock suite. Contributions to Mineralogy and Petrology 18, 105–162. Green, D.H., Ringwood, A.E., 1972. Gabbro-garnet granulite-eclogite transition. Journal of Geology 80, 277–288. Green, H.W., Dobrzhinetskaya, L., Bozhilov, K.N., 2000. Mineralogical and experimental evidence for very deep exhumation from subduction zones. Journal of Geodynamics 30, 61–76. Green, T.H., 1967. An experimental investigation of sub-solidus assemblages formed at high pressure in high-alumina basalt, kyanite eclogite and grosspydite compositions. Contributions to Mineralogy and Petrology 16, 84–114. 194 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Grubenmann, U., 1904–1907. Die Krystallinen Schiefer: Eine Darstellung der Erscheinungen der Gesteinsmetamorphose und ihrer Produkte. Gebrüder Borntraeger, Berlin, I, 105 p.; II, 175 p. Hacker, B.R., Peacock, M., 1995. Creation, preservation, and exhumation of UHPM (ultrahigh pressure metamorphic) rocks. In: Coleman, R.G., Wang, X. (Eds.), Ultrahigh pressure metamorphism. Cambridge University Press, pp. 159–181. Haggerty, S.E., Sautter, V., 1990. Ultradeep (greater than 300 kilometers), ultramafic upper mantle xenoliths. Science 248 (4958), 993–996. (see also: 252 (5007), 827–830). Hall, J., 1859. Palaeontology. In: The Natural History of New York, Part VI. Geological Survey of New York Vol. 3 (part I), 533 p. Hamilton, B., 1992. The influence of the polarising microscope on late nineteenth century geology. Janus LXIX, 51–68. Harris, P.G., Reay, A., White, I.G., 1967. Chemical composition of the upper mantle. Journal of Geophysical Research 72, 6359–6369. Harris, P.G., Rowell, J.A., 1960. Some geochemical aspects of the Mohorovičić discontinuity. Journal of Geophysical Research 65, 2443–2459. Haug, E. 1990. Les géosynclinaux et les aires continentales. Contribution à l’étude des transgressions et des régressions marines. Bulletin de la Société géologique de France (3) 28, 617–711. Hausmann, H., 1845. Beiträge zur Oryktographie von Syra. Göttingische gelehrte Anzeigen, 1845, 193–200 (abstract in Journal für praktische Chemie, 34, 238–241). Haussmann, J.F.L., 1813. Handbuch der Mineralogie1813Bandenhoeck und Ruprecht, Göttingen. 3 Vols/1158 p. (753–756). Hauÿ, R.-J., 1822. Traité de minéralogie. Seconde édition, revue, corrigée et considérablement augmentée par l’auteur. Bachelier et Huzard, Paris, 4 Vols+atlas (t. II, p. 456; t. IV, p. 548). Hentschel, H., 1937. Der Eklogit von Gilsberg im sächs. Granulitgebirge und seine metamorphen Umwandlungsstufen. Mineralogische und Petrographische Mitteilungen 49, 42–88. Hess, H.H., 1962. History of Ocean basins: a volume in honor of A.F. Buddington. In: Engel, A.E.J., James, H.L., Leonard, B.F. (Eds.), Petrologic Studies. Geol. Soc. America, pp. 599–620. Hess, H.H., 1965. Mid-oceanic ridges and tectonics of the sea-floor. In: Whittard, W.F., Bradshaw, R. (Eds.), Submarine Geology and Geophysics (Proc. Symp. Colston Res. Soc.). Butterworths, London, pp. 317–333. Hezner, L., 1903. Ein Beitrag zur Kenntnis der Eklogite und Amphibolite, mit besonderer Berücksichtigung der Vorkommnisse des mittleren Oetztals. Mineralogische und petrographische Mittheilungen 22, 437–472, 505–580. Hiortdahl, Th., Irgens, M., 1862. Geologiske Undersøgelser i Bergens Omegn (with an extended abstract in French); Om Fjeldstykket mellem Laerdal og Urland samt om profilet over Filefjeld af Dr. Theodor Kjerulf. Mallings Bogtrykkeri, Christiania, viii–34 p. (10—15)+1 map and 1 pl. Hirajima, T., Ishiwatari, A., Cong, B., Zhang, R., Banno, S., Nozaka, T., 1990. Coesite from Mengzhong eclogite at Dhonghai county, northeastern Jiangsu province, China. Mineralogical Magazine 54, 579–583. Hochstetter, F., 1855. Geognostische Studien aus dem Böhmerwalde. Jahrbuch der geologischen Reichsanstalt VI, 749–810. (775, 802). Hoffmann, Breithaupt, 1815. Handbuch der mineralogie. Craz und Gerlach, Freiberg, 5 Vols+atlas. Holland, T.H., 1896. On the origin and growth of garnets and of their micropegmatitic intergrowths in pyroxenic rocks. Records of the geological Survey of India 29, 20–30+1 pl. Holland, T.J.B., 1979. High water activities in the generation of high pressure kyanite eclogites of the Tauern window, Austria. Journal of Geology 87, 1–27. Holland, T.J.B., 1980. The reaction albite=jadeite+quartz determined experimentally in the range 600–1200  C. American Mineralogist 65, 129–134. Holland, T.J.B., 1983. The experimental determination of activities in disordered and short-range ordered jadeitic pyroxenes. Contributions to Mineralogy and Petrology 82, 214–220. Holland, T.J.B., 1990. Activities of components in omphacitic solid solutions. An application of Landau theory to mixtures. Contributions to Mineralogy and Petrology 105, 446–453. Holmes, A., 1926. The structure of the continents. Nature 118, 586. Holmes, A., 1931. Radioactivity and Earth movements. Transactions, Geological Society of Glasgow 18, 559–606. Holway, R.S., 1904. Eclogites in California. Journal of Geology XII, 344–358. G. Godard / Journal of Geodynamics 32 (2001) 165–203 195 Hovorka, D., Korikovsky, S., Soják, M., 2000. Neolithic/aeneolithic blueschist axes: northern Slovakia. Geologica Carpathica 51 (5), 345–351. Hunt, Th.S., 1884. The origin of crystalline rocks. Mémoires et Comptes rendus de la Société r. du Canada- Transactions of the r. Society of Canada II, Section III, 1–67. Hurley, P.M., 1968. The confirmation of continental drift. Scientific American 218, 53–64. Ippen, J., 1892. Zur Kenntnis der Eklogite und Amphibolitegesteine des Bachergebirges. Mittheilungen der Naturwissenschaflichen Vereines für Steiermark 1892 (1893), 328–369. Ito, K., Kennedy, G.C., 1970. The fine structure of the basalt-eclogite transition. Special Paper—Mineralogical Society of America 3, 77–83. Jannettaz, Ed., 1867. Note pour servir à l’étude des roches de la Nouvelle-CalédonieBulletin de la Société géologique de France (2) XXIV, 451–453. Joukowsky, E., 1902. Sur les éclogites des Aiguilles Rouges. Soc. générale d’imprimerie, Genève (Thèse), in–8 , 45 p. Julien, A.A., 1909. A bibliography of the diamond fields of South Africa. Economic Geology 4, 453–469. (286 entries). Kennedy, G.C., 1959. The origin of continents, moutain ranges, and ocean basins. American Scientist 47, 491–504. Khitarov, N.I., Ryzhenko, B.N., Lebedev, E.B., 1963. Relations between andalusite, kyanite and sillimanite at moderate temperatures and pressures. Geokhimiya 3, 219–228. (in Russian). Kienast, J.R., 1983. Le métamorphisme de haute pression et basse température (éclogites et schistes bleus): données nouvelles sur la pétrologie des roches de la croute océanique subductée et des sédiments associés. Univ. de Paris VI, Thèse de doctorat d’état, 484 p. Kieslinger, A., 1928. Geologie und Petrographie der Koralpe, VII- Eklogite und Amphibolite. Sitzungsberichte der Akademie der Wissenschaften in Wien. Mathematisch-Naturwissenschaftliche Klasse 137, 401–454+pl. i–ii. Knauer, E., Matthes, S., 1970. Die Eklogitvorkommen des kristallinen Grundgebirges in NE-Bayern. V- Die Opakminerale und Rutil der Eklogite und Eklogitamphibolite des Münchberger Gneisgebietes. Neues Jahrbuch für Mineralogie, Abhandlungen 114 (1), 1–17. Knopf, A., 1948. The geosynclinal theory. Bulletin of the Geological Society of America 59, 649–669. Kolderup, K.F., 1903. Die Labradorfelse des westlichen Norvegens. II Die Labradorfelse und die mit denselben verwandten Gesteine in dem Bergensgebiete. Bergens Museums Aarbog 1903 (12), 129 p.+3 pl (1 map). Korzhinskii, D.S., 1940. Petrology of MetamorphismSelected Works. Nauka-Press, Moscow, 253 p. (in Russian, published in 1993). Koto, B., 1887. A note on glaucophane. Journal of the College of Science, imp. University, Japan (Tokyo) I, 85–99. +pl. xii. Krenner, 1883. Über Jadeit. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1883 (II), 173–174. Krishnan, M.S., 1954. Sir Lewis Leigh Fermor. Current Science 23 (9), 285–286. Kuno, H., 1959. Discussion of paper by J. F. Lovering, ‘‘The nature of the Mohorovičić discontinuity’’ (with Lovering’s reply). Journal of Geophysical Research 64, 1071–1073. Kuno, H., 1967. Volcanological and petrological evidence regarding the nature of the upper mantle. In: Gaskell, Th.F. (Ed.), The Earth’s Mantle. Academic Press, London, pp. 89–110. Kushiro, I., 1969. Clinopyroxene solid solutions formed by reaction between diopside and plagioclase at high pressure. Mineralogical Society of America Special Papers 2, 179–191. Kushiro, I., Yoder Jr., H.S., 1964. Experimental studies on the basalt-eclogite transformation. Carnegie Institution of Washington Year Book 1964, 108–114. Lacroix, A., 1891. Étude pétrographique des éclogites de la Loire-inférieure. Bulletin de la Société des Sciences naturelles de l’Ouest de la France I, 81–114+2 pl. (re-issue: 1995, 17 (3), 76–108+2 pl). Lacroix, A., 1941. Les glaucophanites de la Nouvelle-Calédonie et les roches qui les accompagnent, leur composition et leur genèse. Mémoires de l’Académie des Sciences de l’Institut de France (2 s.) 65, 1–103+pl. i–iv. Lanterno, Ed., 1976. La collection des échantillons décrits par H.-B. de Saussure dans les ‘‘Voyages dans les Alpes’’ déposée au Muséum de Genève. Musées de Genève 162 (Février 1976), 18–22. Lanterno, Ed., 1982. André Amstutz, 12 novembre 1901– 6 mars 1981. Archives des Sciences (Genève) 35, 101–107. Lappin, M.A., Smith, D.C., 1981. Carbonate, silicate and fluid relationships in eclogites, Selje district and environs, SW Norway. Transactions of the r. Society of Edinburgh 72, 171–193. 196 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Lasaulx, A. von, 1883. Der Vortragende legt dann eine Suite von Handstücken eines neuen Glaukophangesteines von der Insel Groix, an der Westküste der Bretagne vor, die er durch Herrn Grafen von Limur in Vannes erhalten hat und macht über das Vorkommen und die mineralogische Zusammensetzung dieses Gesteins folgende Mittheilung. Sitzungsberichte der niederrheinischen Gesellschaft für Natur- und Heilkunde in Bonn (enclosed in: ‘‘Verhandlungen des naturhistorischen Vereines der preussischen Rheinlande und Westfalens’’) XL, 263–274. Lasaulx, A. von, 1884. Die Mineralen eines neuen Glaukophangesteins von der Insel Groix an der Südwestküste des Bretagne. Zeitschrift für Kristallographie IX, 422–424. Laubscher, H., 1969. Mountain building. Tectonophysics 7, 551–563. Lennykh, V.I., Valizer, P.M., Beane, R., Leech, M., Ernst, W.G., 1995. Petrotectonic evolution of the Maksyutov complex, Southern Urals, Russia: implications for ultrahigh-pressure metamorphism. International Geology Review 37, 584–600. Leonhard, K.C. von, 1823. Charakteristik der Felsarten. J. Engelmann, Heidelberg. 230 p. Leontev, L.N., Kadensky, A.A., 1957. O prirode kimberlitovyky trubok YakutiiDoklady Akademii Nauk SSSR 115 (2), 368–371 (in Russian). Le Pichon, X., 1968. Sea-floor spreading and continental drift. Journal of Geophysical Research 73, 3661–3697. Lepsius, R., 1893. Geologie von Attika. Ein Beitrag zur Lehre von Metamorphismus der Gesteine. Reimer, Berlin, in– 4 , 196 p.+viii pl. Lewis, H.C., 1887. On a diamantiferous peridotite, and the genesis of the diamond. Geological Magazine (III) 4, 22–24. Lewis, H.C., 1897. Papers and Notes on the Genesis and Matrix of the Diamond (by the late H.C. Lewis, edited from his unpublished mss. by Prof. T.G. Bonney). Longmans, London, 72 p.+2 pl. Lipold, M.V., 1855. Die kristallinischen Schiefergesteinen in nordöstlichen Kärnthen. Jahrbuch der k. k. geologischen Reichsanstalt VI, 414–416. Lohmann, P., 1884. Neue Beiträge zur Kenntniss des Eklogits, vom mikroskopisch-mineralogischen und archäologischen Standpunkte. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1884 (part 1), 83–115+2 tb (with a comprehensive bibliography). Lovering, J.F., 1958. The nature of the Mohorovičić discontinuity. Transactions—American Geophysical Union 39 (5), 947–955. Lüdecke, 1876. Der Glaucophane und die Glaucophane-führende Gesteine der Insel Syra. Zeitschrift der Deutschen Geologischen Gesellschaft XXVII, 268. Lyell, Ch., 1830–1833. Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation. J. Murray, London, 3 Vols. Macpherson, J., 1881. Apuntes petrográficos de Galicia. Anales de la Sociedad Española de Historia natural X, 49– 87+pl. i. (53–65). Maresch, W.V., 1972. Eclogitic-amphibolitic rocks on Isla Margarita, Venezuela: a preliminary account. Geological Society of America, Memoir 132, 429–437. Marmo, V., 1965. Pentti Eskola 1883–1964. Bulletin de la Commission géologique de Finlande 218, ix–liii. (+1 portrait). Mauthner, J., 1872. Eklogit von Eibiswald in Steiermark. Mineralogische Mittheilungen 1872, 261. McGetchin, T.R., Silver, L.T., 1972. A crustal-upper-mantle model for the Colorado Plateau based on observations of crystalline rock fragments in the Moses Rock Dike. Journal of Geophysical Research 77, 7022–7037. Medaris Jr, L.G. Carswell, D.A., 1990. Petrogenesis of Mg-Cr garnet peridotites in European metamorphic belts. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 260–290. Mennell, F.P., 1910. The geological structure of southern Rhodesia. Quarterly Journal of the geological Society of London 66, 353–375+pl. xxviii (372–375). Meyer, H.O.A., 1979. Kimberlites and the mantle. Reviews of Geophysics and Space Physics 17 (4), 776–788. Miller, C., 1970. Petrology of some eclogites and metagabbros of the Oetztal Alps, Tirol, Austria. Contributions to Mineralogy and Petrology 28, 42–56. Miyashiro, A., 1961. Evolution of metamorphic belts. Journal of Petrology 2, 277–311. Miyashiro, A., 1967. Orogeny, regional metamorphism, and magmatism in the Japanese islands. Meddelelser fra Dansk Geologisk Forening 17, 390–446. Miyashiro, A., 1972. Metamorphism and related magmatism in plate tectonics. American Journal of Science 272, 629– 656. G. Godard / Journal of Geodynamics 32 (2001) 165–203 197 Miyashiro, A., 1973. Metamorphism and Metamorphic Belts. G. Allen & Unwin, London, 492 p. (‘‘History of the study of metamorphism’’: pp. 429–440). Mohorovičić, A., 1910. Potres od 8.x.1909; Das Beben vom 8.x.1909. Godisnje Izvjesce Zagrebackog Meteoroloskog Opservatorija za godinu 1909; Jahrbuch des Meteorologischen Observatoriums in Zagreb für das Jahr 1909 9 (4), 1– 63. Moissan, H., 1893. Sur la préparation du carbone sous une forte pression. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) 116, 218–224. Moissan, H., 1894. Nouvelles expériences sur la reproduction du diamant. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) 118, 320–326. (the results of these works have been much controversed). Monardes, N., 1565. Dos libros. El vno trata de todas las cosas que traen de nuestras Indias Occidentales que siruen al vso de Medicina [among which, ‘‘la piedra dela Yjada’’ (jade)] y como se ha de vsar de la rays del Machoacan, purga excellentissima. El otro libro trata de dos medicinas marauillosas que son contra todo Veneno, la piedra bezaar y la yerua Escuerçonera (...). S. Trugillo, Sevilla, 1 Vol. (ff. fiii r -fv v : de la piedra de sangre, y de la piedra dela Yjada). Montigny, R., Allègre, C.J., 1974. À la recherche des océans perdus: les éclogites de Vendée, témoins métamorphisés d’une ancienne croûte océanique. Comptes rendus hebdomadaires des Séances de l’Académie des Sciences, Série D (Paris) 279, 543–545. Moor, G.G., 1941. Micaceous kimberlites in the north of the central Siberia. Doklady Akademii Nauk SSSR 31 (4), 363–365. Moores, E.M., Vine, F.J., 1971. The Troodos massif, Cyprus, and other ophiolites as oceanic crust; evaluation and implications. Philosophical Transactions of the r. Society of London, Series A 268 (1192), 443–466. Mottana, A., Carswell, D.A., Chopin, Ch., Oberhänsli, R., 1990. Eclogite facies mineral parageneses. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 14–52. Moulle, A., 1885. Mémoire sur la géologie générale et sur les mines de diamants de l’Afrique du Sud. Annales des Mines 7, 193–348+pl. v–ix. Müller, H.H., 1846. Geognostische Skizze der Greifendorfer Serpentin-Partie. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde 1846, 257–288. (266). Nagle, F., 1974. Blueschist, eclogite, paired metamorphic belts, and the early tectonic history of Hispaniola. Geological Society of America Bulletin 85, 1461–1466. Nasdala, L., Massonne, H.-J., 2000. Microdiamonds from the Saxonian Erzbegirge, Germany; in situ micro-Raman characterisation. European Journal of Mineralogy 12, 495–498. Naumann, C.F., 1838. Erläuterungen zu der geognostischen Charte des Königreiches Sachsen und der angränzenden Länderabtheilungen. Dresden und Leipzig I (2), 100–102. Necker, L.A., 1828. Mémoire sur la vallée de Valorsine. Mémoires de la Société de Physique et d’Histoire naturelle de Genève IV, 209–245. (216). Newton, R.C., Smith, J.V., 1967. Investigations concerning the breakdown of albite at depth in the Earth. Journal of Geology 75, 268–286. Niggli, E., 1970. Alpine Metamorphose und alpine Gebirgsbildung. Fortschritte der Mineralogie 47, 16–26+3 pl. Nikitin, V.V., 1942. Prispevek h karakteristiki eklogitov in amfibolitov jugovzhodnega Pohorja in k vprasanju o nastanku eklogitov (with an italian abstract: Contributo alla caratteristica delle eclogiti e delle anfiboliti del Pohorje sudorientale ed al problema della genesi delle eclogiti). Razprave matematicno-prirodoslovnega razreda Akademije znanosti in umetnosti v Ljubljani 2, 299–362. Novarese, V., 1938. Secondo Franchi. Bollettino del r. Ufficio geologico d’Italia LXIII, 1–22. O’Brien, P.J., Carswell, D.A., Gebauer, D., 1990. Eclogite formation and distribution in the European Variscides. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 204–224. O’Hara, M.J., 1967. Mineral facies in ultrabasic rocks. In: Wyllie, P.J. (Ed.), Ultramafic and Related Rocks. John Wiley & Sons, New York, pp. 7–18. Okay, A.I., 1993. Petrology of a diamond and coesite-bearing metamorphic terrain: Dabie Shan, China. European Journal of Mineralogy 5, 659–675. Okay, A.I., Xu, S., Sengor, A.M.C., 1989. Coesite from the Dabie Shan eclogites, central China. European Journal of Mineralogy 1, 595–598. 198 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Oxburgh, E.R., Turcotte, D.L., 1970. Thermal structure of island arcs. Geological Society of America Bulletin 81, 1665–1688. Palache, C., 1894. On a rock from the vicinity of Berkeley containing a new soda amphibole. Bulletin of the Department of Geology of the University of California I, 181–191+pl. 11. Patton, H.B., 1887. Die Serpentin- und Amphibolegesteine nördlich von Marienbad in Böhmen. Mineralogische und Petrographische Mittheilugen IX, 89–144. (123–135). Platt, J.P., 1975. Metamorphic and deformational processes in the Franciscan Complex, California: some insights from the Catalina Schist terrane. Geological Society of America Bulletin 86, 1337–1347. Platt, J.P., 1993. Exhumation of high-pressure rocks: a review of concepts and processes. Terra Nova 5, 119–133. Pearson, D.G., Davies, G.R., Nixon, P.H., Milledge, H.J., 1989. Graphitized diamonds from a peridotite massif in Morocco and implications for anomalous diamond occurrences. Nature 338, 60–62. Perrier, C., 1924. Sulla eclogite filoniana di Voltaggio. Bollettino del r. Ufficio geologico d’Italia L (2), 1–18. Philippot, P., 1993. Fluid-melt-rock interaction in mafic eclogites and coesite-bearing metasediments: constraints on volatile recycling during subduction. Chemical Geology 108, 93–112. Philippot, P., Rumble, D., 2000. Fluid-rock interactions during high-pressure and ultrahigh-pressure metamorphism. International Geology Review 42, 312–327. Piolti, G., 1902. Pirosseniti, glaucofanite, eclogiti ed anfiboliti dei dintorni di Mocchie (Val di Susa). Atti della r. Accademia delle Scienze di Torino XXXVII, 660–666. Råheim, A., Green, D.H., 1975. P,T paths of natural eclogites during metamorphism—a record of subduction. Lithos 8, 317–328. Ranalli, G., Pellegrini, R., D’Offizi, S., 2000. Time dependence of negative buoyancy and the subduction of continental lithosphere. Journal of Geodynamics 30, 539–555. Ransome, F.L., 1894. The geology of Angel Island. Bulletin of the Department of Geology of the University of California I, 193–240+pl. 12–14. Ransome, F.L., 1895. On lawsonite, a new rock-forming mineral from the Tiburon Peninsula, Marin County, California. Bulletin of the Department of Geology of the University of California I, 301–312+pl. 17. Ravier, J., 1964. Ariégites et éclogites. Bulletin de la Société française de Minéralogie et de Cristallographie LXXXVII, 212–215. Reinecke, T., 1991. Very-high-pressure metamorphism and uplift of coesite-bearing metasediments from the ZermattSaas zone, Western Alps. European Journal of Mineralogy 3, 7–17. Retgers, J.W., 1891. Mikroskopisch onderzoek eener verzameling gesteenten uit de afdeeling Martapoera, zuider- en ooster-afdeeling van Borneo. Jaarboek van het Mijnwezen in Nederlandsch Oost-Indië 20, 1–212 (review in Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie, 1893 (I), pp. 39–43; 1893 (II), pp. 176—178). Reusch, H.H., 1877. Grundfjeldet i søndre Søndmør og en Del af Nordfjord. Forhandlinger i Videnskabs-selskabet i Christiania 1877 (11), 1–18+1 map. Reusch, H.H., 1883. Nye Oplysninger om Olivinstenen i Almeklovdalen og Sundalen paa Søndmøre. Forhandlinger i Videnskabs-selskapet i Christiania 1883, 1–18. Riess, E.R., 1878. Untersuchungen über die Zusammensetzung des Eklogits. Mineralogische und petrographische Mittheilungen 1878, 165–172, 181–241. Ringwood, A.E., 1962. A model for the upper mantle. Journal of Geophysical Research 67, 857–867, 4473–4477. Ringwood, A.E., 1970. Phase transformations and the constitution of the mantle. Physics of the Earth and Planetary Interiors 3, 109–155. Ringwood, A.E., Green, D.H., 1964. Experimental investigations bearing on the nature of the Mohorovicic discontinuity. Nature 201 (4919), 566–567. Ringwood, A.E., Green, D.H., 1966. An experimental investigation of the gabbro-eclogite transformation and some geophysical implications. Tectonophysics 3, 383–427. Ringwood, A.E., Major, A., 1971. Synthesis of majorite and other high pressure garnets and perovskites. Earth and planetary Science Letters 12, 411–418. Rivière, A., 1835. Note sur la carte géognostique de la Vendée. Comptes-Rendus hebdomadaires des Séances de l’Académie des Sciences (Paris) I, 237. (see also II, 1836, 136–138). G. Godard / Journal of Geodynamics 32 (2001) 165–203 199 Rivière, A., 1844. Mémoire minéralogique et géologique sur les roches dioritiques de la France occidentale. Bulletin de la Société géologique de France (2) I, 528–569. Roever, W.P. de, 1955. Genesis of jadeite by low-grade metamorphism. American Journal of Science 253, 283– 298. Rubie, D.C., 1990. Role of kinetics in the formation and preservation of eclogites. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 111–140. Sahlstein, Th.G., 1935. Petrographie der Eklogiteinschlüsse in den Gneisen des südwestlichen Liverpool-Landes in OstGrönland. Meddelelser om Grönland 95 (5), 43+1 pl. Saussure, H.-B. de, 1779–1796. Voyages dans les Alpes, précédés d’un essai sur l’histoire naturelle des environs de Genève. S. Fauche, Neuchâtel, 4 Vols. Schmädicke, E., 1991. Quartz pseudomorphs after coesite in eclogites from the Saxonian Erzgebirge. European Journal of Mineralogy 3, 231–238. Schmädicke, E., 1994. Die Eklogite des Erzgebirges. Freiberger Forschungshefte, Leipzig C456, 338 p. Schneer, C.J., 1997. La dernière ‘‘Théorie de la Terre’’: James Hall et le concept de géosynclinal. In: Gohau, G. (Ed.), De la Géologie à son Histoire. Comité des Travaux Historiques et Scientifiques, Paris, Mémoire de la Section des Sciences, Vol. 13, 189–192. Schrauf, A., 1882. Beiträge zur Kenntniss des Associationskreises der Magnesiasilicate. Zeitschrift für Kristallographie und Mineralogie 6, 321–388. Schreyer, W., 1988. Subduction of continental crust to mantle depths: Petrological evidence. Episodes 11, 97–104. Schulze, D.J., Helmstaedt, H., 1988. Coesite-sanidine eclogites from kimberlite: products of mantle fractionation or subduction? Journal of Geology 96, 435–443. Schürmann, H.M.E., 1950. Glaukophanegesteine aus Venezuela. Neues Jahrbuch für Mineralogie, Monatshefte 1950, 145–156. Schürmann, H.M.E., 1951–1956. Beiträge zur Glaukophanefrage. Neues Jahrbuch für Mineralogie, Monatshefte 1951, 49–68; Abhandlungen 85, 303–394+pl. 11–87; Abhandlungen 89, 41–84. Schuster, M., 1878. Eklogit aus Altenburg (Nieder-Oesterreich). Mineralogische und petrographische Mittheilungen (n.f.) 1, 368. Sederholm, J.J., 1916. On synantetic minerals and related phenomena (reaction rims, corona minerals, kelyphite, myrmekite, &c.). Bulletin de la Commission géologique de Finlande 9 (n 48), iv–148+8 pl. Shemenda, A.I., Mattauer, M., Bokun, A.N., 1996. Continental subduction and a mechanism for the exhumation of high-pressure metamorphic rocks: new modelling and field data form Oman. Earth and planetary Science Letters 143, 173–182. Sheynmann, Yu.M., 1963. The Mohorovičić discontinuity, depth of magma origin, and the distribution of ultrabasics. International Geology Review 5 (2), 171–179. (translated from Sovetskaya Geologiya, 1961, 8, 31–44). Smith, D.C., 1982. The essence of an eclogite: AlVI, as exemplified by the crystal-chemistry and petrology of highpressure minerals in Norwegian eclogites. Terra Cognita 2 (3), 300. Smith, D.C., 1984. Coesite in clinopyroxene in the Caledonides and its implications for geodynamics. Nature 310 (5979), 641–644. Smith, D.C. (Ed.), 1988a. Eclogites and Eclogite-facies Rocks. Developments in petrology, Vol. 12 Elsevier, Amsterdam, 524 p. Smith, D.C., 1988b. A review of the peculiar mineralogy of the ‘‘Norwegian coesite-eclogite province’’, with crustalchemical, petrological, geochemical and geodynamical notes and an extensive bibliography. In: Smith, D.C. (Ed.), Eclogites and Eclogite-facies Rocks. Elsevier, Amsterdam, pp. 1–206. Smith, D.C., 1995. Microcoesites and microdiamonds in Norway: an overview. In: Coleman, R.G., Wang, X. (Eds.), Ultrahigh Pressure Metamorphism. Cambridge University Press, Cambridge, pp. 299–355. Smith, J.P., 1906. The paragenesis of the minerals in the glaucophane-bearing rocks of California. Proceedings of the American philosophical Society XLV, 183–242. Smulikowski, K., 1960. Comments on eclogite facies in regional metamorphism. Report of the international geological Congress 21st Session, Norden (Part XIII), 372–382. Smulikowski, K., 1964a. An attempt at eclogite classification. Bulletin de l’Académie polonaise des Sciences, Série des Sciences géologiques et géographiques XII, 27–33. 200 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Smulikowski, K., 1964b. Le problème des éclogites [in French]; Zagadnienie Eklogitow (in Polish). Geologia Sudetica 1 13–52, 53–77. Smyth, J.R., Hatton, C.J., 1977. A coesite-sanidine grospydite from the Roberts Victor kimberlite. Earth and planetary Science Letters 34, 284–290. Sobolev, N.V., Shatsky, V.S., 1986. (Problems of genesis of eclogites from metamorphic complexes). Geologia i Geofizika 1986 (9), 3–11. (in Russian, with an English abstract). Sobolev, N.V., Shatsky, V.S., 1987. Carbon mineral inclusions in garnets of metamorphic rocks. Geologiya i Geofizika 28 (7), 77–80. (in Russian, with an English abstract). Sobolev, N.V., Shatsky, V.S., 1990. Diamond inclusions in garnets from metamorphic rocks: a new environment for diamond formation. Nature 343, 742–746. Sobolev, V.S., Sobolev, N.V., 1971. Priroda granitsy Mokhorovichicha i mineral’nyy sostav verkhney chasti mantii po petrograficheskim dannym (Nature of the Mohorovicic discontinuity and the mineral composition of the upper mantle based on petrographic data). In: Priroda seysmicheskikh granits v zemnoy kore. Akad. Nauk SSSR, Nauchn. Sovet Kompleksn. Issled. Zemnoy Kory Verkhn, Moscow, pp. 112–116. Sørensen, H., 1953. The ultrabasic rocks at Tovqussacq, West Greenland. A contribution to the peridotite problem. Meddelelser om Grönland 136 (4), 86+9 pl. Stegena, L., 1966. On the possibility of diffusion at the M discontinuity. Bollettino di Geofisica Teorica ed Applicata 8 (32), 309–317. Steinmann, G., 1927. Die ophiolithischen Zonen in den mediterranen Kettengebirgen. Congrès géologique international. Comptes Rendus de la XIVe session, Espagne 1926 (t. 2), 638–668. Stella, A., 1894. Relazione sul rilevamento eseguito nell’anno 1893 nelle Alpi Occidentali (Valli dell’Orco e della Soana). Bollettino del r. Comitato geologico d’Italia 25, 343–371+pl. iii. Stella, A., 1933. Commemorazione del socio corrispondente Secondo Franchi. Atti della r. Accademia dei Lincei. Rendiconti. Classe di scienze fisiche, matematiche en naturali 17, 1010–1019. Stishov, S.M., 1962. On the internal structure of the Earth. Geochemistry (English version of Geokhimiya) 1962 (8), 751–763. Stishov, S.M., Popova, S.V., 1961. A new dense modification of silica. Geochemistry (English version of Geokhimiya) 1961 (10), 923–926. Strüver, von, 1875. Sulla gastaldite, nuovo minerale del gruppo dei bisilicati anidri. Atti della r. Accademia dei Lincei, Memorie della Classe di scienze fisiche, matematiche e naturali (2 s.) II, 333. Suzuki, J., 1924. On the glaucophane schists in Japan. Chishitsugaku zasshi (Journal of the Geological Society of Tokyo) XXXI, 1–17. Switzer, G., 1945. Eclogite from the California glaucophane schists. American Journal of Science 243, 1–8. Tagiri, M., Bakirov, A., 1990. Quartz pseudomorph after coesite in garnet from a garnet-chloritoid-talc schist, Northern Tien-Shan, Kirghiz SSR. Proceedings of the Japan Academy, ser. B 66, 135–139. Taliaferro, N.L., 1943. Franciscan-Knoxville problemBulletin of the American Association of Petroleum Geologists 27 (2) 109–219+pl. i–vii (159–182). Tarkov, A.P., Chamo, S.S., Nadezhka, L.I., 1971. Structure of the crystalline crust and subcrustal layer of the Voronezh Block, as revealed by deep seismic sounding. Transactions (Doklady) of the U.S.S.R. Academy of Sciences: Earth Science Sections 198 (1-6), 47–50. (translated from Doklady Akademii Nauk SSSR, 1971, 198, pp. 182–185). Teall, J.J.H., 1891. On an eclogite from Loch Duich. The Mineralogical Magazine and Journal of the Mineralogical Society IX, 217–218. Termier, P., 1891. Étude sur la constitution géologique du massif de la Vanoise (Alpes de Savoie). Bulletin des Services de la Carte géologique de France II (20), 367–513+pl. i–x. Thompson, J.B., 1947. Role of aluminium in the rock-forming silicates. Bulletin of the Geological Society of America 58, 1232. Traube, 1889. Ueber ein Vorkommen von Eklogite bei Frankenstein in Schlesien. Neues Jahrbuch für Mineralogie, Geologie und Paleontologie 1889 (part 1), 195–200. Trommsdorff, V., Hermann, J., Müntener, O., Pfiffner, M., Risold, A.-Ch., 2000. Geodynamic cycles of subcontinental lithosphere in the Central Alps and the Arami enigma. Journal of Geodynamics 30, 77–92. Van Hise, C.R., 1898. A treatise on metamorphism. U.S. Geological Survey Monograph 47, 1286 p. G. Godard / Journal of Geodynamics 32 (2001) 165–203 201 Van Roermund, H.L.M., Drury, M.R., Barnhoorn, A., De Ronde, A.A., 2000. Super-silicic garnet microstructures from an orogenic garnet peridotite, evidence for an ultra-deep (>6 GPa) origin. Journal of metamorphic Geology 18, 135–147. Verhoogen, J., 1954. Petrological evidence on temperature distribution in the mantle of the Earth. TransactionsAmerican Geophysical Union 35, 85–98. Vine, F.J., Matthews, D., 1963. Magnetic anomalies over oceanic ridges. Nature 199, 947–949. Vogel, D.E., Garlick, G.D., 1970. Oxygen-isotope ratios in metamorphic eclogites. Contributions to Mineralogy and Petrology 28, 183–191. Vraná, S., Prasad, R., Fediuková, E., 1975. Metamorphic kyanite eclogites in the lufilian arc of Zambia. Contributions to Mineralogy and Petrology 51, 139–160. Wagner, P.A., 1914. The Diamond Fields of Southern Africa. Gothic printers, Capetown, 355 pp. Wadati, K., 1935. On the activity of deep-focus earthquakes in the Japan Islands and neighbourhoods. Geophysical Magazine 8, 305–325. Wall, G.P., 1860. On the geology of a part of Venezuela and of Trinidad. Quarterly Journal of the Geological Society of London 16, 460–470+pl. xxi. Wallis, S.R., Ishiwatari, A., Hirajima, T., Ye, K., Guo, J., Nakamura, D., Kato, T., Zhai, M., Enami, M., Cong, B., Banno, S., 1997. Occurrence and field relationships of ultrahigh-pressure metagranitoid and coesite eclogite in the Su-Lu terrane, eastern China. Journal of the Geological Society, London 154, 45–54. Wang, Q., Ishiwatari, A., Zhao, Z., Hirajima, T., Hiramatsu, N., Enami, M., Zhai, M., Li, J., Cong, B., 1993. Coesitebearing granulite retrograded from eclogite in Weihai, eastern China. European Journal of Mineralogy 5, 141–152. Wang, X., Liou, J.G., Mao, H.K., 1989. Coesite-bearing eclogites from the Dabie Mountains in central China. Geology 17, 1085–1088. Wang, X., Zhang, R., Liou, J.G., 1995. UHPM [Ultrahigh-pressure metamorphic] terrane in East Central China. In: Coleman, R.G., Wang, X. (Eds.), Ultrahigh Pressure Metamorphism. Cambridge University Press, Cambridge, pp. 356–390. Washington, H.S., 1922. The jade of the Tuxtla statuette. Proceedings of the US national Museum LX (2409), 12 p.+1 pl. Weinschenk, E., 1904. Beiträge zur Petrographie der östlichen zentral Alpen, speziell des Gross-Venedigerstockes. IIIDie Kontaktmetamorphische Schieferhülle und ihre Bedeutung für die Lehre vom allgemeinen Metamorphismus. Abhandlungen der mathematisch-physikalischen Classe der königlich bayerischen Akademie der Wissenschaften (München) XXII, 261–340+pl. i–vi (286–291). Weir, C.E., Lippencott, E.R., Van Valkenburg, A., Bunting, E.N., 1959. Infrared studies in the 1- to 15-micron region to 30,000 atmospheres. Journal of Research of the national Bureau of Standards, Section A 63, 55–62. Werner, A.G., 1817. Abraham Gottlob Werner’s lektes Mineral-System, aus dessen Nachlasse aus oberbergamtliche Anordnung herausgegeben und mit Erläuterungen versehen. Craz, Gerlach, Carl Gerold, Freyberg und Wien, xiv–58 p. West, W.D., 1989. Profile of an earth scientist; Sir L.L. Fermor. Indian Journal of Geology 61, 133–136. White, A.J.R., 1964. Clinopyroxenes from eclogites and basic granulites. American Mineralogist 49, 883–888. White, D.A., Roeder, D.H., Nelson, Th.H., Crowell, J.C., 1970. Subduction. Geological Society of America Bulletin 81, 3431–3432. Wickman, F.E., 1943. Some aspects of the geochemistry of igneous rocks and of differentiation by crystallisation. Geologiska Föreningens i Stockholm Förhandlinger 65, 371–396. (394). Wieseneder, H., 1935. Beiträge zur Kenntnis der ostalpinen Eklogite. Mineralogische und Petrographische Mittheilungen 46, 174–211. (with a comprehensive bibliography). Williams, A.F., 1932. Genesis of the Diamond, 2 Vols. Williams, G.H., 1890. The Greenstone Schist areas of the Menominee and Marquette regions of Michigan. A contribution to the subject of dynamic Metamorphism in Eruptive Rocks. US Geological Survey, Bulletin 62, 241+16 pl. Wilson, T., 1965. A new class of faults and their bearing on continental drift. Nature 207, 343–347. Wyllie, P.J., 1965. A modification of the geosyncline and tectogene hypothesis. Geological Magazine 102, 231–245. Wyllie, P.J., 1970. Ultramafic rocks and the upper mantle. Mineralogical Society of America, Special Paper 3, 3–32. Xu, S., Su, W., Liu, Y., Jiang, L., Ji, S., Okay, A.I., Sengor, A.M.C., 1991. Diamond in the high pressure metamorphic rocks in the eastern part of the Dabie Mountains. Kexuetongbao 17, 1318–1321. (see also: Science, 1992, 256, 80–82). 202 G. Godard / Journal of Geodynamics 32 (2001) 165–203 Yang, J., Godard, G., Kienast, J.R., Lu, Y., Sun, J., 1993. Ultrahigh-pressure (60 kbar) magnesite-bearing garnet peridotites from northeastern Jiangsu, China. Journal of Geology 101, 541–554. Yang, J., Smith, D.C., 1989. Evidence for a former sanidine-coesite-eclogite at Lanshantou, Eastern China, and the recognition of the Chinese ‘‘Su-Lu Coesite-Eclogite Province’’. Terra Abstracts 1, 26. Yoder Jr., H.S., 1950. The jadeite problem. American Journal of Science 248, 225–248. 312–334. Yoder Jr., H.S., 1955. Role of water in metamorphism in crust of the Earth. Geological Society of America, Special Paper 62, 505–523. Yoder Jr., H.S., 1993. Timetable of petrology. Journal of Geological Education 41, 447–489. Yoder Jr., H.S., Tilley, C.E., 1962. Origin of the basalt magmas: an experimental study of natural and synthetic rocks systems. Journal of Petrology 3, 342–532+10 pl. Zambonini, F., 1901. Su un pirosseno sodifero dei dintorni di Oropa, nel BielleseAtti della r. Accademia dei Lincei. Rendiconti. Classe di Scienze Fisiche, Matematiche e Naturali (5) 10, 240–244. Zambonini, F., 1906. Ueber den metamorphosierten Gabbro des Rocca Bianca im Susa-Tale. Neues Jahrbuch für Mineralogie, Geologie und Palaeontologie 1906 (2), 105–134. Zhang, S., Hu, K., Liu, X., Chang, L.1991. Discovery of minute grains of diamond and native gold in coesite-bearing eclogites from the Dabie-north Jiangsu-east Shandong region (in Chinese) Chinese Geology 11, 28–29. Zirkel, F., 1894. Lehrbuch der Petrographie. Engelmann, Leipzig, 3 Vols (t. 3, pp. 360–370). Zittel, K. von, 1899. Geschichte der Geologie und Paläontologie bis Ende des 19. Jahrhunderts. Drud und Berlag, München und Leipzig, xi-868 p. (translated by Ogilvie-Gordon, M.M., 1901. History of Geology and Palaeontology to the End of the Nineteenth Century. London, 1901, xiv-562 p.; re-issue: Cramer, 1962). Further reading Alderman, A.R., 1936. Eclogites in the neighbourhood of Glenelg, Inverness-Shire. Quarterly Journal of the Geological Society of London 92, 488–530. Angel, F., 1957. Einige ausgewählte Probleme eklogitischer Gesteinsgruppen der österreichischen Ostalpen. Neues Jahrbuch für Mineralogie, Abhandlungen 91, 151–192. (with an extensive bibliography). Busch, K., Knauer, E., Matthes, S., Richter, P., Seidel, E., Schmidt, K., 1967–77. Die Eklogitvorkommen des kristallinen Grundgebirges in NE-Bayern. Neues Jahrbuch für Mineralogie, Abhandlungen 107, 74–112; 112, 1–46; 113, 111–137, 138–178; 114, 1–17; 117, 143–182; 120, 270–314; 122, 186–208; 126, 45–86; 129, 269–291. Chesnokov, B.V., 1959. Rutile-bearing eclogites of the Shubinskoe ore deposit, South Urals. Izvestia Vysshih uchebnyh zavedenij Geologia i razvedka 4, 124–136. (in Russian). Dobretsov, N.L., Sobolev, N.V., 1970. Eclogites from metamorphic complexes of the USSR. Physics of the Earth and Planetary Interiors 3, 462–470. Droop, G.T.R., Lombardo, B., Pognante, U., 1990. Formation and distribution of eclogite facies rocks in the Alps. In: Carswell, D.A. (Ed.), Eclogite Facies Rocks. Blackie, pp. 225–259. Engels, J.P., 1972. The catazonal poly-metamorphic rocks of Cabo Ortegal (NW Spain), a structural and petrographic study. Leidse geologische Mededelingen 48, 83–133+1 map. Hahn-Weinheimer, P., Lueke, W., 1966. Berechnungen zur Klassifizierung eklogitisher Gesteine. Krystalinikum 1966, 55–64. Martin, S., Tartarotti, P., Dial Piaz, G.V., 1994. The Mesozoic ophiolites of the Alps: a review. Bollettino di Geofisica teorica ed applicata XXXVI (141–144), 175–219. Matthes, S., 1986. The eclogites of Southern Germany—a summary. Neues Jahrbuch für Mineralogie, Monatshefte 1978 (3), 93–109. Meyer, H.O.A., Boyd, F.R., 1968. Mineral inclusions in diamonds. Carnegie Institution of Washington Year Book 67, 130–135. (first analysis of inclusions in diamond). Miyashiro, A., 1994. Metamorphic petrology. UCL Press, London, 404 p. (‘‘A history of metamorphic petrology’’: pp. 355–372). Morten, L. (Ed.), 1993. Italian eclogites and related rocks, including a field guide book. Accademia nazionale delle Scienze detta dei XL (Roma). Scritti e documenti (4th international Eclogite Conference) XIII, 275 p. G. Godard / Journal of Geodynamics 32 (2001) 165–203 203 Ploshko, V.V., Shpot, H.P., 1974. Eclogite formation in the Great Caucasus. Izvestiya Akademii Nauk SSSR 12, 60– 71. (in Russian). Richardson, S.H., Gurney, J.J., Erlank, A.J., Harris, J.W., . Origin of diamonds in old enriched mantle. Nature 310, 198–202. (3-billion-year-old diamonds in kimberlite). Tatrishvili, N.F., . A discovery of eclogite in the greater Caucasus. Dokaldy of the Academy of Sciences of the U.S.S.R. (English version of Doklady Akademii Nauk SSSR) 190, 170–172. Tilley, C.E., . On the paragenesis of Kyanit-eclogites. Mineralogical Magazine 24, 422–432. Udovkina, N.G., . (Eclogitization of ultrabasic rocks of the Polar Urals). Trudy Instituta Geologii Rudnyh Mestorogdenii, Petrografii, Mineralogii i Geokhimii 32, 5–18. (in Russian). Wolff, T. von, . Methodisches zur quantitativen Gesteins- und Mineral-Untersuchung mit Hilfe der Phaseanalyse (am Beispiel der mafischen Komponenten des Eklogits von Silberbach). Mineralogische und Petrographische Mitteilungen 54 (1–3), 1–222. View publication stats