Facies Analysis

The digital storage and communication of significant geological data became increasingly more objective and accessible through the development of new technologies or the implementation of already well-known techniques as photogrammetry. Digital acquisition of geometries (both structural and depositional) of significant geological outcrops is deemed necessary, especially if the site concerned is liable to be damaged or hopelessly involved in natural processes of geological and geomorphological evolution. In this paper, we tested the performances of two different open-source software (i.e. VisualSFM and ARC3D) on a small-scale but paradigmatic outcrop in the Umbria-Marche Apennines (Italy). The test showed that ARC3D provides an high-resolution model, employing a relatively short time and requiring a not expensive hardware support for processing hundreds of photos. In the text, 3D models of the selected outcrop are reported and discussed emphasizing the potential of the method to high...

The Sandakan Formation of the Segama Gorup is exposed across the Sandakan Peninsula in eastern Sabah. This Upper Miocene part of the Segama Group unconformably overlies the Garinono Formation and is conformably overlain by the Bongaya Formation. This formation was investigated with detailed logging of outcrops and microfossils analysis in order to map the depositional facies and sedimentary environment. This study reveals the presence of seven lithofacies 1) Thick amalgamated sandstone, 2) Thin, lenticular interbedded HCS sandstones and mudstone, 3) Laminated mudstone with Rhizophora, 4) Trough Cross-bedded sandstone 5) Laminated Mudstone, 6) Strip mudstone with thin sandstone and siltstone 7) Interbedded HCS sandstone and mudstone. Based on the presence of Rhizophora, Brownlowia, Florchuetia sp., Polypodium, Stenochleana Palustris, Ascidian Spicule, low angle cross bedding, very fine grained sandstone, thin alternations of very fine sandstone, silt and clay layers showing cyclicity (muddy rhythemites), rocks in the Sandakan Formation are interpreted as mangal estuary and open marine facies. Three facies associations could be deduced from the seven lithofacies; 1) Gradual coarsening upwards shoreface, 2) abrupt change facies, and 3) prograding estuary facies association.

Lower Cretaceous sequences of the Burgan Formation are notable siliciclastic reservoirs in the Middle East. Despite of this importance, a little is known about various geological characteristics of this reservoir in Iranian northwestern part of the Persian Gulf. In this study, an integrated sedimentological and reservoir geological evaluation has been carried out on the Burgan reservoir using a complete dataset of drilled cores, core plugs, thin sections and petrophysical logs along with laboratory data including XRD analysis of all components to define grain's mineralogy and porosity – permeability data for reservoir quality evaluation. Depositional facies and environments are interpreted and correlated in sequence stratigraphic framework of targeted reservoir across the studied fields and then compared with stratigraphic equivalents in the Middle East. Seven facies types are recognized that indicate deposition in a transitional environment from siliciclastic-dominated delta setting into shallow-marine carbonate platform. Diagenesis study indicates a simple history of post-depositional events that includes near surface (marine) and shallow to deep burial realms. Diagenetic processes are grouped into two categories based on their effects on reservoir properties. They include porosity enhancing (i.e. dissolution and fracturing) and porosity reducing (compaction and cementation) diagenetic processes. Reservoir evaluation of depositional facies has been carried out by defining petrographic rock-types (PRTs) and hydraulic flow units (HFUs) and their correlation in sequence stratigraphic framework. Results showed that semi-to unconsolidated sandstone facies accumulated in Burgan-B member provides the best reservoir units in the Burgan Formation. Organic-rich (rootled) and pelagic shale facies form several intra-reservoir barriers between the reservoir units, especially in Burgan-A member. These show close correlation with reservoir descriptions of this formation reported from the neighboring areas in the Persian Gulf (i.e. Kuwait).

The facies models are the most powerful method for the genetic interpretation of the stratigraphic record, acting as syntheses of the facies relationships. Nowadays, the facies relationship interpretation is fundamented either by the Walther's Law (or Facies Correlation Law) or by the application of geostatistic tests. On the other hand, the present stratigraphic basin analysis search for stratal discontinuities (actually bedding surfaces). It is the bedding surface hierarchization, according to its physical magnitude (scale), that have revealed a usefull way for the facies association diagnosis. In accordance to this practise, it is adopted the postulate of that facies contained between bedding surfaces of the same hierarchical order, in one stratigraphic succession, without the intervenience of a bedding surface of greater magnitute, are genetically related one to each other, and may be conceived in association. This postulate differs from the universalized facies diagnosis procedures for not making use of the magnitude of the stratal discontinuities as a physical argument of the facies relationship falsification (unconformities in the Walther's Law), but as the foundation of its interpretation; furthermore, it takes away the necessity of geostatistic tests as an argument to the relationship verification, which only determines the possible and probable relations.

Stratigraphic exposures, fluvial archives and borehole data have been allowed to reconstruct the alluvial history of Late Pleistocene to Late Holocene and climate changes in the monsoonal wet – dry region of lower Damodar Basin (West Bengal, India). The facies architectures and climate proxies suggest that five to six climate changes occurred in between ~ 14 ka and 6 ka. Supporting evidence from the floodplain of Damodar River demonstrates that the successive phases of aggradation and incision were linked to the south-west monsoonal variability of Late Quaternary period. The onset of semi-arid climate was associated with caliches, pond and backswamp deposits of wanning low energy floods. The relatively warm-humid climate was associated with sandy bedforms, valley fills, slack water deposits and ferruginous nodules. This paper presents a synthesis of the available palaeoclimatic records from the lower Ganga Basin and the rivers of western and central India for the palaeoenvironmental significance of Late Quaternary deposits and discusses the influence of palaeoclimatic controls on the fluvial architectures and archives that developed below the floodplain of Damodar River. We have taken some representative studies from the region to reveal the spatial variability in fluvial successions in response to climate changes during this period.

This Thesis was Submitted in Partial Fulfillment of the requirements for the Master’s Degree of Science in Geology Faculty of Graduate Studies, The University of Jordan: The Triassic Period witnessed a global palaeoceanographic change through the opening of Neo-Tethys Ocean, when the northern margins of Gondwana were affected by sea level fluctuations causing successive marine transgressions and regressions. The southern Mediterranean Gondwanan shelf that extended from Morocco (African plate) to Oman (Arabian sub-plate) was likewise affected by the opening of Mesozoic Neo-Tethys Ocean (Makhlouf,2006).
The Neo-Tethys shoreline approached the western shoulder of Gondwana diachronously during the middle Triassic times; Jordan was, partially, flooded by the Neo-Tethys Ocean and, as a result of this gradual transgression leading to deposition of middle and upper Triassic Formations; when Iraq el Amir and Umm Tina Formations were deposited (Makhlouf,2006).
The middle Triassic (Ladinian) strata of NW Jordan (Iraq el Amir and Umm Tina Formations) consist of medium –to-thick bedded limestones with various skeletal (bivalves, algae, corals, echinoderms, brachiopods, crinoids, ostarcods, and serpulid) and nonskeletal (peloid) components. Facies analysis documents the depositional environments, including tidal, lagoonal, barrier and open marine facies.
Four third order depositional sequences can be distinguished in each of the two stratigraphic measured outcrop sections. In the subsurface four and three third order depositional sequences are distinguished in Ajloun-1 and Northern highland-2 deep wells for the two formations respectively.
Transgressive systems tracts (TST) show deepening upward trends, in which shallow water (tidal flat and lagoonal) facies are overlain by deep water (open marine) facies, highstand systems tracts (HST) show shallowing upward trends in which relatively deep water facies are overlain by shallow water facies. All sequence boundaries in the study locality (except the top of the stratigraphic column) are of the non-erosional (SB2) type.
Correlation of depositional sequences in the studied sections shows that relatively shallow marine (tidal flat, lagoonal, sand shoal, and shallow open marine) conditions dominated in the area. These facies are alternating with deeper water open marine packstone, grainstone representing zones of maximum flooding surface (MFS).

Chattian mixed carbonate-siliciclastic deposits from two palaeogeographic units of Southern Alps, the Lessini Shelf and Venetian foreland basin of northeast Italy, are studied with respect to facies distributions and controlling ecological factors on dominant biogenic components. These ramp depositional systems are located in the western Southern Alps on the Lessini Shelf, and in the eastern Southern Alps in the Venetian foreland basin. The successions show an extensive geographic distribution of at least 150 km × 40 km at the southern margin of the Southern Alps. Palaeoenvironments are inferred following microfacies characteristics and floral and faunal indicators, especially those of coralline red algae and larger foraminifera. An inner- to middle homoclinal ramp morphology is reconstructed based on facies distributions and taxonomic and coralline algal growth-form proxy data.

The distribution along depositional strike shows variation from thinner, carbonate dominated sequence in the west (Monti Berici and Monti Lessini) to a more variable, mixed carbonate-siliciclastic dominated environment to the east (Vittorio Veneto, Alpago). Facies character and occurrence are controlled by local hydrodynamic conditions and varying water turbidity of the studied ramp depositional system. The general facies succession shows a transgressive sequence from the proximal inner- to proximal middle ramp. A shoal belt of trough cross-bedded sandstones occurs in a proximal inner ramp position in all of the studied areas. In a gentle-dipping homoclinal ramp, most benthic organisms inhabited the relatively quite environments off these shoals in a distal inner ramp setting. Basinward environments (proximal middle ramp) constitute areas of maximal carbonate production and consist primarily of larger foraminiferal facies and rhodolith pavements. Larger foraminifera, represented by two larger foraminiferal assemblages, are most diversified in the shallower settings (near the fair-weather wave base, distal inner/proximal middle ramp), whereas coralline algae predominate in deeper areas (proximal middle ramp) constructing extensive rhodolith pavements. Rhodolith pavements are distinguished with respect to rhodolith shape, size, growth-forms and coralline algal taxonomic composition. Larger foraminifera are interpreted with respect to shell structures, shell architectures and comparable Recent counterparts.

The analysed benthic communities thrived in a mesotrophic regime within trophic gradients constrained by fluvial influence. Coralline algal dominance and a moderately diverse larger foraminiferal assemblage suggest a tropical/warm temperate transition. The considerable stability imposed on sediments by the rhodolith pavement must also have significantly contributed to the maintenance of a middle ramp profile bulge. This study will contribute to a better understanding of Oligocene carbonates which have received less attention than their Eocene or Miocene counterparts.

Condensed ammonoid beds of the Hallstatt facies (Anisian-Ladinian) are widespread around the Ancient Theatre of Epidaurus, in the locality Theokafta of the Argolis Peninsula (eastern Peloponnesus). The Hallstatt Formation in Argolis appears, generally, in the form of lensoid bodies of variable sizes, inclination and direction and is always found overlying a formation consisting of keratophyric tuffs. In fact, the contact of the keratophyric tuffs with the overlying limestones, specifically evidenced by an in situ brecciated zone, is stratigraphic and constitutes the base of the Hallstatt Limestones. The contact of the Hallstatt Limestones with the overlying radiolarites is stratigraphic as well.

Los flujos submarinos de densidad (FSD) o “flujos submarinos”, son los procesos que más volumen de sedimentos transportan en nuestro planeta y desarrollan abanicos submarinos.

Los abanicos submarinos incluyen sistemas canalizados capaces de alojar hidrocarburos en cantidades comerciales. Por esta razón, resulta conveniente realizar modelos que representen la heterogeneidad de
los yacimientos en sistemas clásticos profundos, mediante la asociación de facies y la determinación de sus áreas fuente.

El presente trabajo discute los avances en el entendimiento de los FSD depositados en aguas profundas, como parte de un sistema de transporte continuo desde el continente. Estos depósitos pueden ser turbiditas, debritas, complejos de transporte en masa (CTM) e hiperpicnitas, diferenciados por su geometría, continuidad,
conectividad y clases de facies. Por tal motivo, es importante usar análogos de afloramiento para comprender a sus equivalentes en el subsuelo, considerando que la variabilidad arquitectura final está gobernada por controles autocíclicos (e.g., área fuente, ambiente de depósito, eficiencia y entropía del sistema), y alocíclicos como cambios en el nivel del mar, dinámica salina y condiciones tectónicas y climáticas.

Finalmente, se describe una clasificación textural útil para distinguir clases de facies en ambientes de aguas profundas y modelos de abanico submarino dependientes del área fuente y eficiencia del sistema. Estos se caracterizan mediante la granulometría, que puede ser cuantificada en afloramientos, muestras de mano, láminas delgadas, núcleos, muestras de canal y mediante el análisis del registro de rayos gamma.

The study of the uppermost section of the Early Cretaceous Agrio Formation in northern Patagonia (Neuquén Basin) where dinosaur tracks assigned to cf. Therangospodus pandemicus are exposed (tracksites I and II) evidence mixed marginal marine siliciclastic-carbonate deposits. The succession was divided in two intervals. A lower one containing theropod tracks, recorded on top of subtidal oolithic limestones with tiny wave ripples suggesting shoreline fluctuations and subaerial exposure. Tidal influence is recognised by fining upward and prograding cycles starting with subtidal carbonates and ending with fine-grained siliciclastic deposits at the top, or rarely laminites. Dolomitization affects subtidal deposits generated in an alkaline media stressful for tracemakers. Intertidal facies include abundant heterolithic deposits, coquinas composed of gastropods encrusted by multilayered bryozoans and muddy levels with incipient mud cracking. Invertebrate ichnofossils recognized from tidally dominated deposits include Arenicolites, Kouphichnium, and Rhizocorallium. The upper interval is a transgressive-regressive cycle that starts with dark shales, deficiently oxygenated, and covered by prograding sandstones and finally sand flat deposits. This interval contains Gyrochorte, Hillichnus, and Ophiomorpha documented in wave-influenced sandstones. Dinosaur tracks as well as Hillichnus, attributed to tellinoid bivalves, and Kouphichnium assigned to xiphosurans, imply the activity of producers rarely recorded previously as body fossils in marginal marine deposits of southern South America. Previous paleogeographic schemes are questioned by our analysis, which shows evidence of extremely shallow and tide-controlled sedimentation, sometimes with subaerial exposure, with high cyclicity related to a marginal marine depositional setting and lack of significant erosion by the overlying unit, as traditionally was suggested.

The Asmari Formation was deposited in the foreland basin of southwest Iran (Zagros Basin). Carbonate sequences of the Asmari Formation consist mainly of large benthic foraminifera along with other skeletal and non-skeletal components. Three assemblage zones have been recognized by distribution of these large foraminifera in the study area that indicate Oligocene age (Rupelian-Chattian). Absence of turbidite deposits, reefal belt and gradual facies changes indicate that the Asmari Formation was deposited in a carbonate ramp environment. Based on analysis of large benthic foraminiferal assemblages and microfacies features nine different microfacies have been recognized, which can be grouped into three depositional environments: inner, middle and outer ramp. Based on the microfacies analysis and sequence stratigraphic studies, two third-order sequences in Firozabad section were identified.

The late Pliocene to early Pleistocene siliciclastic succession of western Emilia (northern Italy) forms part of the infill of the Po Plain-Adriatic foredeep, a collisional basin with active thrusting during deposition, and is characterized by 5to-20-m-thick fining-upward sedimentary cycles. Late Pliocene cycles were deposited in an inner-to-middle shelf setting at the end of a long-term uplift-denudation cycle controlled by tectonics. Cycles are characterized by shell beds of biogenic origin, particularly abundant in the middle of each cycle. The stacking pattern of paleocommunities, with particular reference to their paleodepths, reflects that each cycle is the product of sea-level variation. In particular, early transgressive deposits are marked by a Nuculana community, indicating a shelly-sand bottom of the inner shelf; late transgressive deposits and the condensed section are marked by a shelly bottom Timoclea community developed at times of lowered clastic input; highstand deposits are characterized by a muddy soft bottom Pinna community. The situation changed near the boundary of the early Pleistocene, when a new uplift-denudation cycle started, renewing sediment availability and increasing the slope of the nearby mountain front. Local climatic conditions periodically triggered the sudden delivery on the shallow shelf of large amounts of sediment through hyperpycnal flows and related turbidity currents generated by catastrophic river floods. Sandy shelfal lobes form the lower reaches of the delta front. These are characterized by densely packed shell beds and the occurrence of echinoderm obrution deposits. Recurring sedimentological assemblages from sandstones, characterized by the sandy bottom Spisula and Ditrupa communities, and in situ faunas from intervening mudstones, characterized by the muddy-bottom, hypoxic Arctica (and Corbula ?) community, suggest that the lower part of a cycle formed during deglaciation following glacial maxima, at times of high input of freshwater and river-borne nutrients and high summer pelagic productivity. Mudstones from the upper part of the cycle, with dispersed remains of the muddy-bottom Venus community, indicate return to full interglacial conditions and to humid, low seasonality climates. Thus, early Pleistocene cycles could be correlative to sapropel-non sapropel cycles typical of the eastern Mediterranean deep water successions. Moreover, the western Emilia fossil and sedimentary records suggest that cyclic deposition was controlled by factors other than eustasy, providing a case study for future sequence stratigraphic modeling in active tectonic settings.

The Strzelecki Group incorporates Berriasian to Albian, fluvial sediments deposited in the Gippsland Basin during initial rifting between Australia and Antarctica. Neocomian strata of the lowermost Strzelecki Group are assigned to the Tyers River Subgroup (exposed in the Tyers area) and the Rhyll Arkose (exposed on Phillip Island and the Mornington Peninsula). The Tyers River Subgroup incorporates two formations: Tyers Conglomerate and Rintoul Creek Formation. The latter is subdivided into the Locmany and Exalt Members. Ten fluvial sedimentary facies are identified in the lowermost Strzelecki Group: two gravelly facies; four sandy facies; and four mudrock facies. Associations of these facies indicate: (i) prevalence of gravelly braided-river and alluvial-fan settings during deposition of the Tyers Conglomerate; (ii) more sluggish, sandy braided to meandering fluvial systems during Locmany Member sedimentation; and (iii) a return to active, sandy, braided-river settings for deposition of the Exalt Member. The Tyers Conglomerate and Rhyll Arkose rest on an irregular erosional surface incised into Palaeozoic rocks of the Lachlan Fold Belt. The overlying Rintoul Creek Formation incorporates more mature sediments where lithofacies associations varied according to base-level change, variations in subsidence rates, and/or tectonic uplift of the principal sediment source terranes to the northwest.

Ancient deltaic facies are difficult to differentiate from tidally influenced shallow-marine facies. The Wagad Sandstone Formation of the Wagad Highland (eastern Kachchh Basin) is typified by offshore and deltaic facies with sedimentary characteristics that represent different conditions of hydrodynamics and related depositional processes. The study area, the Adhoi Anticline, constitutes a ~154-m-thick, shale-dominated sequence with progressive upward intercalations of bioturbated micritic sandstone and quartz arenite. Two thick Astarte beds (sandy allochemic limestone), with an erosional base and gravel blanketing, illustrate tidal amplification and high-energy stochastic events such as storms. Sedimentological characteristics document three depositional facies: an offshore, shale-dominated sequence prograding to proximal prodeltaic micritic sandstone and quartz arenite with sandy allochemic limestones, further prograding to mouth bars and abandoned channel deposits. The Wagad Sandstone Formation displays depositional environmental conditions that are dissimilar from those of coeval deposits in Kachchh sub-basins as well as on regional and global
scales. This is attributed to a reactivation of the Kachchh Mainland and South Wagad faults which resulted in detachment and uplift of the Wagad block which then experienced prograding deltaic conditions.

The Madneuli polymetallic deposit is the major deposit of the Bolnisi ore district in the southeastern part of Georgia, which is in production since the 70's. The Bolnisi district is part of the Lesser Caucasus; it extends towards the west in the Eastern Pontides, Turkey. The origin of the Madneuli deposit is still controversial. Our study is based on physical volcanology and sedimentary basin analyses. Eleven principal volcanic and volcano-sedimentary facies types were identified within the Madneuli open pit based on their composition, texture, volcanic and sedimentary structures. The presence of various submarine sedimentary structures, hyaloclastite and turbiditic rocks and Radiolaria described for the first time within the host rocks of the Madneuli open pit, supports the submarine depositional setting for the volcano-sedimentary succession hosting the Madneuli deposit.

This paper presents the results of a high-resolution analysis of Upper Cretaceous shallow-water limestones in the northeast sector of the Lepini Mountains (Central Apennines, Italy) that belong to the Latium-Abruzzi platform domain. The studied succession is entirely referred to as the ''Accordiella conica & Rotorbinella scarsellai Biozone''. The analyzed Coniacian-Campanian succession is primarily characterized by three lithofacies associations (LF-A, LF-B, LF-C) deposited on an open shelf. The intertidal and shallow-subtidal environments are characterized by mudstone to wackestone and laminated bindstone (LF-C), whereas in the low to moderate energy environments of the inner shelf there developed rudist biostrome (rudist pillarstone) and rudist rudstone to floatstone (LF-A). A lithofacies association dominated by cross-bedded grainstone (LF-B) represents the reworking of bioclastic grains (rudist fragments) derived from the areas of the shelf colonized by rudist biostrome; lime-sand shoals related to storm channels passed into submarine dunes in an open-shelf setting. Correlation of the five investigated stratigraphic sections shows how the recognized LF are laterally associated to form a facies mosaic over a few hundred meters. The stratigraphic architecture shows five intervals (I-V) each of which is dominated by one or two LF. Interval I is intensely dolomitized. The following intervals (II and III) record a gradual increase in hydrodynamic energy as evidenced by the presence of rudist biostromes passing upward into cross-bedded grainstone. An increase in mud-supported textures in the interval IV suggests more restricted conditions, which were terminated by a period of emergence. More open-marine conditions in the final interval (V) are shown by the dominance of LF-A and LF-B.

The Flagstone Bench Formation ranges in age from earliest Triassic to Norian (Late Triassic) and is exposed in the Beaver Lake area of the northern Prince Charles Mountains. This sandstone-dominated formation rests conformably on the Bainmedart Coal Measures and represents the upper part of the Permian–Triassic Amery Group. It is divisible into three members: the Ritchie, Jetty and McKelvey members (in ascending order). Nine sedimentary facies assignable to three facies associations (major channel, crevasse/fan and flood-basin deposits) are recognized within the formation. Ritchie Member sedimentation took place during a transition from consistently hygric to seasonally dry conditions and the unit comprises sandstone-dominated, sheet-like channel deposits interspersed with few, thin, mottled, haematite-rich floodbasin siltstones. Deposition took place under fluctuating discharge conditions chiefly within the channel tracts of axially (northwesterly/northeasterly) flowing, low-sinuosity braided rivers. The Jetty Member shows a gross upward-fining profile dominated in the lower part by poorly sorted pebbly sandstones and in the upper part by ferruginous mudcracked siltstones, mottled palaeosols, calcrete and thin massive sandstone sheets. This unit reflects deposition of easterly directed alluvial fans and extensive flood-basin silt under a semi-arid climatic regime. The Upper Triassic sandstone-dominated McKelvey Member shows a return to axial drainage along the Lambert Graben with sedimentation occurring primarily within lowsinuosity braided channel tracts under wetter climatic conditions.

Carbonate mud that accumulated in the deep parts of a late Kimmeridgian carbonate ramp (Iberian Basin, NE Spain) was partly derived by resedimentation from shallow water production areas. High-frequency sea- level changes, probably driven by climatic changes in tune with precession and short-eccentricity cycles, affected carbonate production and the amount of exported sediment. Facies analysis and correlation of three outcrops located in middle and outer ramp settings allows a comparison of high-order sequences (bundles of beds and sets of bundles) across a ramp transect and an assessment of the carbonate factory. Analysis of the storm deposits found in middle ramp settings identifies deepening to shallowing high-frequency cycles based on the level of exported carbonate. In outer ramp areas, many of the bundles exhibit a thinning trend, indicating a progressive decrease of carbonate production and hence, carbonate export during periods of high- frequency sea-level rise. δ13Ccarb values show a gradual increase through the studied long-term transgressive interval ranging from 1.5‰ to 2.8‰. Within this long-term evolutionary trend, short-term δ13Ccarb fluctuations occur that correspond with some of the high-order cycles defined from sedimentary facies analysis. These short-term δ13Ccarb shifts are interpreted as shifts in carbonate export from shallow reef regions to the outer ramp. A consequence of this study is that variation in δ13Ccarb can be used for correlation in outer ramp successions, at least on a basin-wide scale.

L'étude céramologique du site d'Arancou – Las Courrèges (Pyrénées‐Atlantiques, France), outre corroborer les données archéologiques ayant révélé une occupation datant de la seconde moitié du Ier s. ‐ IIème s. de notre ère, vient offrir de nouvelles données et correspondances statistiques sur le faciès de consommation ainsi que de nouveaux profils, notamment une

During the past decade, the size of 3D seismic data volumes and the number of seismic attributes have increased
to the extent that it is difficult, if not impossible, for interpreters to examine every seismic line and time
slice. To address this problem, several seismic facies classification algorithms including k-means, self-organizing
maps, generative topographic mapping, support vector machines, Gaussian mixture models, and artificial neural
networks have been successfully used to extract features of geologic interest from multiple volumes. Although
well documented in the literature, the terminology and complexity of these algorithms may bewilder the average
seismic interpreter, and few papers have applied these competing methods to the same data volume. We have
reviewed six commonly used algorithms and applied them to a single 3D seismic data volume acquired over the
Canterbury Basin, offshore New Zealand, where one of the main objectives was to differentiate the architectural
elements of a turbidite system. Not surprisingly, the most important parameter in this analysis was the choice of
the correct input attributes, which in turn depended on careful pattern recognition by the interpreter. We found
that supervised learning methods provided accurate estimates of the desired seismic facies, whereas unsupervised
learning methods also highlighted features that might otherwise be overlooked.

Variations in the sedimentary organic matter were documented throughout the Agua de la Mula Member (late Hauterivian) of the Agrio Formation, at a combined section in the type area of the Agrio Formation; the base at Agrio del Medio and the middle to top at Bajada del Agrio. A main organic-rich interval was identified in the basal Agua de la Mula Member, dominated by marine-derived Amorphous Organic Matter (AOM), coinciding with the highest Total Organic Carbon (TOC) content, between 1.4 and 3.8 wt.%, suggesting dysoxic conditions. The rest of the Member is predominantly characterized by terrestriallyderived organic matter, mainly phytoclasts, with low TOC values, around 1% or lower, indicating predominantly oxic depositional settings. By integrating stacking pattern and shell beds analysis, four depositional sequences SQ1eSQ4 were recognized. The organic-rich, finely laminated bituminous black shales of the Spitidiscus riccardii zone constitute a mayor and rapid inundation defining a Transgressive System tract (TST), related to a third order asymmetrical mesosequence dominated by a thick High System Tract (HST). It represents the most widespread and important flooding episode within the Neuquén Basin during the late Hauterivian. Inside sequences of higher frequency (SQ1, SQ2, SQ3, SQ4) of probably fourth order were recognized and analysed including several ammonids zones (Spitidiscus riccardii, Crioceratites schlagintweiti, C. diamantensis and Paraspiticeras groeberi). With the exception of the oxygen-controlled, basinal and outer ramp settings indicated for the TST1, which is equivalent to the TST of a lower order sequence, and the lower TST2, respectively, the prevalence of well oxygenated, inner to middle ramp depositional environments, is suggested for the rest of the sedimentary succession and emphasized in HST of SQ2, SQ3 and SQ4. Thus, a shallowing-upward trend with improved oxygenation is recorded through the Agua de la Mula Member, reflected by decreasing TOC, AOM content and preservation state of the organic matter. Based on the whole rock fluorescence analysis of the two selected organic-rich intervals from the Spitidiscus riccardii and the lowermost Crioceratites diamantensis zones, the presence of hydrocarbons suggests a very early in situ generation.

Un articolato progetto di ricerca, riguardante 10 studio del primo sottosuolo della pianura costiera dell'Arno, e in corso di svolgimento attraverso una convenzione tra il Dipartimento di Scienze Geologiche dell'Universita di Pisa (responsabile scientifico Dott. Giovanni Sarti) e il Comune di Pisa (referente Dott. Marco Redini) con la collaborazione del Dipartimento di Scienze della Terra e Geologico Ambientali dell'Universita di Bologna (responsabile scientifico Prof Alessandro Amorosi).

A detailed grain size analysis of 27 samples of sandstones supported by lithofacies of the 400 m thick Middle Siwalik Subgroup, north-western Himalaya, India, was done to understand the dynamics of sedimentation. Lithofacies supports sedimentation in a wide foreland basin setting by migrating river channels flowing along the SW palaeoslopes and carrying sediment loads from the Himalaya. Though, some of the rivers seem to have deposited calcrete conglomerates reworking preexisting foreland basin sediments. The increased sandstone body thickness and grain size in the upper levels of the succession imply sedimentation under progressively humid climatic conditions coupled with enhanced tectonics at the source. Grain size analysis shows that most of the sandstone samples are in the size range of fine-grained sandstones, and only a few are in medium and very fine grained categories. In general, sediments are moderately well sorted, positively to negatively skewed and mainly leptokurtic to mesokurtic suggesting deposition under fluctuating energy conditions in different geomorphic domains within a fluvial setting. Bivariate plots combining the textural parameters also imply continental sedimentation for the Middle Siwalik Subgroup of the study area. Cumulative curves and C-M plot suggest sedimentation transport mainly by saltation and bottom suspension processes under varying energy conditions in aggrading channels.

M. 2008: Foraminifer communities and environmental change in marginal marine sequences (Pliocene, Tuscany, Italy). Lethaia , Vol. 41, Fossil abundance data on foraminifer communities were collected in marginal marine sediments of the Pliocene Valdelsa succession, in Tuscany, Italy. This succession is organized in a hierarchy of elementary and composite depositional sequences. Multivariate techniques allowed to analyse the dataset and reconstruct gradients in species distributions. Species-level data available on modern environmental distributions were used to reconstruct Pliocene environmental gradients and to infer absolute palaeodepths and palaeosalinities. Estimates were then compared with the sequencestratigraphic interpretation to check for consistency. The high-resolution stratigraphic framework allowed us to test the stability of foraminifer communities against ecological variations related to high-frequency glacio-eustatic cycles. The results confirm that fossil distributions of foraminifer species can be used as a fine tool to detect environmental change and that multivariate techniques allow their interpretation in terms of absolute variations of controlling parameters. Salinity is the main contributor to the sum of depth-related factors that regulate foraminifer distributions in coastal facies. In the same setting, nutrient levels and the presence of a sea grass cover are responsible for secondary changes in shallow-water distributions. Below the wave base, however, depth-related parameters other than salinity explain the largest variations. This study indicates that foraminifer communities are random associations of species that respond individualistically to environmental change. ᮀ Community stability , foraminiferal palaeoecology , gradient analysis , sequence stratigraphy .

Sedimentological and palynological studies have been undertaken on a sequence of Permian rocks exposed in the vicinity of Fairbairn Dam, near the town of Emerald in central Queensland. The rocks represent part of the fill of the northern Denison Trough, a north-south elongate feature on the western margin of the Bowen Basin. The present investigation sheds new light on the depositional environment and stratigraphic context of the exposed sequence. The section is interpreted as the product of coastal environments of deposition. Five lithofacies are recognized and interpreted as: (1) major distributary channel fill: thick, erosively based, cross-bedded sandstone; (2) interdistributary bay deposits: thinly interbedded sandstone, siltstone and claystone with carbonaceous shale; (3) tidal inlet and tidal delta deposits: erosively based, bimodally cross-bedded sandstones; (4) beach ridge deposits: massive, quartzose sandstone beds; and (5) middle-upper shoreface (i.e. inner marine shelf) facies: amalgamated units of hummocky cross-stratified sandstones. Evidence for tidal flux and the importance of wave-generated structures suggests that the coastal complex was of mixed-influence, affected by a balance between fluvial outflow, waves and tides. Regional correlations suggest that the exposed section represents an eastward prograding coastal plain without any pronounced deltaic depocentres. Palynological assemblages from four samples support an interdistributary bay interpretation for the thinbedded facies, and indicate a Late Permian age for the exposed sequence. Palynofloras, which are dominated by pterophyte spores and disaccate gymnosperm pollen in three samples, and algae and acritarchs in the fourth, are characteristic of the upper stage 5 palynozone of Price (1983). The age and lithostratigraphic correlation suggest that the rocks exposed in the vicinity of the dam spillway are part of the Freitag Formation.

Four sections of mainly Middle Devonian (Givetian) shallow-marine rocks at the northern margin of Gondwana (Central Iran) were investigated with a special focus on the Bahram Formation, as the stratigraphic range of the Bahram Formation is uncertain and still under discussion. Generally, the Bahram Formation is discontinuously underlain by the Lower Devonian Padeha Formation and disconformably overlain by the Permian Jamal Formation. Conodont communities from the four sections in the Soh area (Najhaf and Neqeleh sections) and the Natanz area (Varcamar and North Tar sections) were investigated. The most widely applied conodont standard zonation of the Upper Givetian contain taxa characteristic of deeper shelf facies whereas conodont fauna of the investigated sections mainly show affinities to shallow-marine environments. Shallow-water conodont associations corresponding to the expansus Zone and subterminus Zone are described from Central Iran for the first time, whereas the vast majority of icriodontid and polygnathid faunas were reported from shallow-marine carbonates around Laurussia (e.g. North America, and Europe). Thirty-six species and subspecies were assigned to five genera (Ancyrodella, Bipennatus, Icriodus, Polygnathus and Pandorinellina). The sedimentological record is characterised by remarkable lateral facies changes, but in the upper part of the Givetian, a general transgressive trend is obvious due to the dominance of limestones and small biostromes.

Abstract
The Eocene transgressive deposits of the Acıgöl, Burdur and Isparta basins are the best exposed of the SW Turkey and shed light on one of the outstanding problems of the tectono- sedimentary evolution during paleotectonic and neotectonic period. In the present paper we describe a tectonic model of the
progressive foreland migration of the allochthonous units such as Lycian and Antalya nappes, initial
emplacement onto stable carbonate platform in the Early Oligocene, carrying piggy-back basins and
incorporating from alluvial fan to deep-marine deposits recognized in these terrigenous successions.
In general, the facies and structural observations on the overall Mid-Late Eocene clastic sequences,
outcropping in behind the Lycian nappes, indicate: i) the alluvial fan to shallow marine settings of the
Başçeşme Fm in Acıgöl, ii) the Varsakyayla Fm in Burdur and iii) proximal to distal flysch facies
trend of the Kayıköy Fm in Isparta. The collected data allow us to hypothesize that the Mid-Late Eocene tectono-sedimentary history was characterized by a terrigenous clastics, probably lying on the constructing tectonic edifice and then deformed and covered by a piggy-back like sequence. The
tectono-sedimentary evolution of the Eocene transgressive in SW Turkey has been probably developed through a progressive migration towards the foreland basin.

The mass extinction of the olenellid trilobites occurred around the Cambrian Series 2–Series 3 boundary. Like many other crises, it coincided with a negative carbon isotope excursion but the associated palaeoenvironmental changes remain unclear. To investigate the causal mechanism for this event, we report facies changes, pyrite framboid petrography and carbon isotope values from Cambrian Series 2–Series 3 (traditionally Early–Middle Cambrian) boundary strata of the Carrara Formation (Death Valley region, California) and Pioche Formation (Nevada). These data reveal regionally changing water depths from high-energy, nearshore facies (oolitic grainstone) to more offshore silty marl and finer-grained carbonate mudstone. In the Carrara Formation, the series boundary occurs within a deepening succession, transitioning from high-energy, nearshore facies (oolitic grainstone and oncolitic packstone) to offshore marl, the latter of which contains pyrite framboid populations indicative of low-oxygen (dysoxic) depositional conditions. Intermittent dysoxia persisted below sub-wave base settings throughout the early and middle Cambrian, but did not intensify at the time of extinction, arguing against anoxia as a primary cause in the olenellid trilobite extinction. Within both field areas, the extinction interval coincided with a minimum in δ 13 C carb values, which we interpret as the regional manifestation of the Redlichiid-Olenellid Extinction Carbon isotope Excursion (ROECE). The Series 2–Series 3 boundary is reported to closely coincide with a large-amplitude sea-level fall that produced the Sauk I/II sequence boundary, but the placement of the Series 2–Series 3 boundary within a transgressive interval of the Carrara Formation shows that this is not the case.The main sequence boundary in the succession occurs much lower in the succession (at the top of the Zabriskie Quartzite) and therefore precedes the extinction of the olenellids and ROECE.

Three outcrops of the Silurian Sharawra Formation at its type locality in Old Qusaiba Village in Central Saudi Arabia were studied for lithofacies distribution, petrographical, and geochemical characteristics. The outcrops were logged and nine different lithofacies were identified in the field. Petrographic analysis shows the Sharawra Formation to be mainly subarkosic associated with increasing mica content near to its contact with the underlying Qusaiba Shale Formation. Major and trace element geochemistry indicates that the sediments of the formation were deposited in a passive continental margin. The source area discriminating plots reveal acidic or felsic rocks such as granites as the probable provenance of the Sharawra sediments. The Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) indicate a moderate degree of weathering in the source area of these Silurian sediments. This study provides a baseline for future characterization studies of Paleozoic siliciclastic formations in Saudi Arabia and neighbouring countries.

Study of a Holocene fan delta in Adventfjorden, Spitsbergen, provides new insight into the nature of high-arctic coastal sedimentation and deglaciation dynamics. The fjord-side, gravelly Gilbert-type fan delta began to form at the local marine limit c. 10 ka BP, supplied seasonally with sediment by meltwater from a cirque glacier left behind by the retreating Late Weichselian ice sheet. Relative sea level had fallen by 63 m, and the fan delta reached a radius of c. 1 km by 6 ka BP, when the relic glacier eventually melted down and fluvial activity declined. A strong influence of marine processes is recorded by the fan-delta foreset facies, overlain by alluvium. Supplied with sediment by longshore drift, the fan-delta front continued to advance at a lower rate, while relative sea level fell further by 5 m and ceased to fall around 5AE4 ka BP. The following transgression was countered by longshore sediment supply until 4AE7 ka BP, when the delta-front beach aggraded and a spit platform began to climb onto the delta plain, recording a relative sea-level rise of 4 m. The subsequent regression was initially non-depositional, with the relative sea level falling by > 4 m in 200 years, outpacing fluvial supply, and the re-emerging fan delta being swept by longshore currents. A regressive beach began to form c. 4AE3 ka BP, while relative sea level gradually reached its present-day position. The feeder braided stream was wandering across the delta plain during this time, but incised once the fan-delta shoreline began to retreat by wave erosion and turned into a receding modern escarpment. The stream has since been adjusting its profile by gradually eroding the pre-existing alluvium and distributing the coarse sediment supplied from catchment slopes by debrisflows and snow avalanches. Modern snowflows have also spread debris onto the abandoned fan surface. The erosional retreat of the fan delta has been accompanied by lateral shoreline accretion on both its sides. The study has important regional implications and demonstrates that Holocene fan deltas can provide a valuable record of the deglaciation history in high-arctic terrains, where glacial deposits are scarcely preserved on land.

Clastic-carbonate succession which including the Nahr Umr and Mauddud Formations are represented a part of Albian-Early Turonian Sequence (Wasi`a Group). The present study includes Petrography, microfacies analysis, depositional environment, digenetic development, and reservoir characterization for seven boreholes (Lu-2, Lu-4, Lu-5, Lu-8, Lu-13, Lu-14 and Lu-39) within Luhais Oil field South Iraq.
There are six type of carbonate microfacies were recognized in the Mauddud Formation:- Orbitolina - Milliolids wackestone to packstone Orbitolina wackestone to packstone, miliolids wackestone, Peloidal wackestone to packstone, Ooides to Peloids grainstone and bioclastic Wackestone - Packstone. These microfacies are represented three depositional environments: restricted shallow marine environment, semi-restricted shallow marine environment and Shoal environments. While the Nahr Umr Formation characterized by six lithofacies; Lithofacies I (Mudstone), Lithofacies II (Siltstone - Claystone), Lithofacies III (Lenticular Bedded Sandstone-Mudstone), Lithofacies IV (Falser Bedded Mudstone - Sandstone), Lithofacies V (Parallel Lamination Sandstone - Siltstone) and Lithofacies VI (Well sorted sandstone). These lithofacies are suggested four depositional environment of Nahr Umr Formation: Active channel environment, channel fill environment, delta plain environment and delta front and shore face environment.
The most common diagenetic features observed and distribution in the studied sections includes Micritization, Cementation, Leaching (dissolution), dolomitization and Compaction fabrics. The most effective diagenetic processes were cementation, dissolution and dolomitization processes which have direct affect upon the study sections.
The Nahr Umr and Mauddud sequence can be divided by the gamma ray and shale value into three zones (A, B and C); therefore we have interpretation of the logs porosity and porosity evaluation according to these divisions.
Keywords: Facies Architecture, Diagenetic Development, Albian-Early Turonian and Luhais Oil field

Aetostreon pilmatuegrossum sp. nov., a large and very convex ostreid from the Pilmatué Member of the Agrio Formation (Neuqué n Basin, Argentina), is described based on specimens recovered from upper Valanginian beds of the Pseudofavrella angulatiformis and Neocomites sp. ammonite subzones. This work also includes a general morphologic discussion of the well-known Lower Cretaceous oysters from Europe, Asia and Africa, most of them considered synonymous of Aetostreon latissimum (Lamarck) in the last decades. The left valves of these oysters share a set of morphological characters that seems to respond to a very distinct but conservative anatomical pattern inherited from their direct ancestor, instead of evidence for their taxonomic uniformity at the species level. Specifically, they show differences in several characters and/or their degree of development and co-occurrence in a particular growth stage, which probably have systematic value, as in the species here described. Aetostreon pilmatuegrossum sp. nov. is probable closely related to an undescribed lower Valanginian species recorded in the Chachao Formation of the Neuqué n Basin, and also has affinities with an association of Barremian oysters from South Africa that seems to be its direct descendant.

"Thecideid brachiopods are poorly known brachiopods of debated phylogenetic relationships which occur from the Late Triassic to the Recent. Although well known in encrusting communities of
Jurassic and Cretaceous cryptic habitats, they have received less attention in Cenozoic environments. Extensive thin section analysis of circumalpine Paleogene carbonates (Late Eocene of
Austria as well as the Early Oligocene of Slovenia, the Inntal Valley and Northern Italy) has revealed the presence of thecideid brachiopods allowing for the analysis of their taphonomy,
component relationships and facies distribution. The complex morphology of the valves enables these brachiopods to be readily identified in thin section, even if highly fragmented or encrusted.
Component analyses using semi-quantitative and quantitative methods reveal that these brachiopods are most commonly associated with corals and coralline algae. The brachiopods are often included within complex encrustation sequences. Their palaeoecology thus closely mirrors that of Recent and fossil thecideid species which are characteristics of cryptic habitats in tropical and warm temperate seas. The potential of these minute brachiopods as palaeoecological indicators has been underestimated especially considering their ease of recognition in thin section not only of complete valves, but also of highly fragmented material. "

We studied mollusk-dominated multispecies assemblies from the south Pyrenean foreland in Spain by using relative abundance data in a framework of high-frequency depositional sequences for an in- terval spanning 2 myr across the early Eocene climatic optimum. The sequences are part of the Figols (middle Ypresian) and Castigaleu (upper Ypresian) allogroups and together document environmental changes influenced by tectonics at the lower frequency and driven by sea level and climate at the high-frequency temporal scale. We ap- plied ordination through multidimensional scaling and other tech- niques to explore the structure of the data set. Six Figols and eight Castigaleu communities, linked along onshore-offshore gradients, were interpreted on uniformitarian grounds. Paleoenvironments ranged from mangrove forest to tidal flat, tidal creek, estuary, delta front, shoreface, carbonate ramp, and inner shelf. Some habitats were represented throughout the interval, allowing examination of the ef- fect on coastal ecosystems of environmental disturbances tied to sea- level lowstands, as deduced from the sequence stratigraphic analysis. These disturbances presumably amounted to extirpation by river floods, burial, increased turbidity, high river-derived nutrient input, and decreased ecospace availability. The major effect on the man- grove-estuary-delta gradient was coincident with the unconformity separating the two allogroups. Mangrove communities suffered a change in rank of dominating species and a turnover of rare species. Subtidal estuarine and delta communities were affected in their rel- ative abundances, but we observed no change in rank or turnover. We suggest that the different niche breadth of organisms leads to different responses to perturbation of several scales. Many intertidal cerithioidean gastropods went extinct, whereas subtidal turritelline gastropods were unchanged, during the major environmental varia- tion. Mangrove gastropods experienced increased originations in the upper Ypresian. The carbonate ramp heterotrophs did not change across the Figols-Castigaleu perturbation, although throughout the early Eocene the phototroph guild within the same ecosystem was undergoing frequent turnover events. All studied associations showed significant changes in the relative abundances of constituent species across unconformities of minor entity, proving that soft-bottom ma- rine communities conform to an open-membership model of ecosys- tem recruitment, as suggested by studies of past open marine eco- systems. Persistence to a degree is suggested by mangrove commu- nities, indicating a slightly more limited membership in low-nutrient estuarine habitats, a response more similar to that of coral reef trop- ical ecosystems. This study confirms the idea that different species and communities may experience opposite effects from the same events and shows that faunal distributions in estuarine and deltaic systems reflect more than just bathymetric change. High onshore origination also conforms to the theory of onshore-offshore faunal change.

Globally, the Series 2 – Series 3 boundary of the Cambrian System coincides with a major carbon isotope excursion, sea-level changes and trilobite extinctions. Here we examine the sedimentology, sequence stratigraphy and carbon isotope record of this interval in the Cambrian strata (Durness Group) of NW Scotland. Carbonate carbon isotope data from the lower part of the Durness Group (Ghrudaidh Formation) show that the shallow-marine, Laurentian margin carbonates record two linked sea-level and carbon isotopic events. Whilst the carbon isotope excursions are not as pronounced as those expressed elsewhere, correlation with global records (Sauk I – Sauk II boundary and Olenellus biostratigraphic constraint) identifies them as representing the local expression of the ROECE and DICE. The upper part of the ROECE is recorded in the basal Ghrudaidh Formation whilst the DICE is seen around 30m above the base of this unit. Both carbon isotope excursions co-occur with surfaces interpreted to r...

RIASSUNTO: Sarti et al. I depositi del Pleistocene inferiore della bassa Val di Cecina (Toscana, Italia): ricostruzione stratigrafico-deposizionale e proposta di suddivisione in Unita' Allostratigrafiche (IT ISSN 0394-3356, 2007). Nella zona compresa fra gli abitati di Riparbella e Casale Marittimo (bassa Val di Cecina, Toscana, Italia) affiorano diffusamente depositi pleistocenici. Attraverso un rilevamento di dettaglio ed un'analisi di facies sono state individuate, all'interno dei depositi del Pleistocene inferiore, cinque unità litostratigrafiche successivamente raggruppate in tre Unità Allostratigrafiche (UA). La più antica (UA7), discordante sui depositi pre-quaternari, è costituita da due unità litostratigrafiche di ambiente marino-deltizio, in parziale eteropia ("Conglomerati delle Ginepraie" e "Sabbie ed argille ad Arctica islandica") organizzate in un ciclo trasgressivo-regressivo. La seconda (UA6), che giace in discordanza angolare sulla UA7, è anch'essa costituita da due unità ("Conglomerati delle Lame" e "Arenarie e Sabbie di Montescudaio") di ambiente marino litorale delle quali è preservata solo la porzione trasgressiva. La terza (UA5, "Conglomerati di Serra all'Olio") discordante sulle precedenti si è invece depositata in un ambiente fluviale di tipo braided. La posizione stratigrafica di questa unità rende probabile una sua attribuzione al Pleistocene medio. Questo tipo di ricostruzione stratigrafico deposizionale differisce fortemente dalle precedenti interpretazioni. ABSTRACT: G. Sarti et.al., Stratigraphic and depositional reconstruction of the Lower Pleistocene deposits from lower Val di Cecina (Tuscany, Italy): a proposal of subdivision in Allostratigraphic Units. (IT ISSN 0394-3356, 2007). In the area comprised between the villages of Riparbella and Casale Marittimo (lower Cecina Valley, Tuscany, Italy) a large amount of Pleistocene deposits outcrops. Through a detailed geological survey integrated with facies analysis five litostratigraphic units, grouped in three Allostratigraphic Units (UA), have been detected. The oldest (UA7), lower pleistocenic in age, is formed by two litostratigraphic units ("Conglomerati delle Ginepraie" and "Sabbie ed argille ad Arctica islandica") showing latero-vertical relationships and are organized in a transgressive-regressive cycle. The "Conglomerati delle Ginepraie" are arranged in a fining upwards trend and were deposited in small coalescent deltaic environments. Three depositional facies are recognized within the "Sabbie ed argille ad Arctica islandica" recording a fining-coarsening and deepening shallowing upward trend. The UA7 lies in unconformity above pre-quaternary deposits.