More than 15 years of field and laboratory investigations on samples from Terre Adélie to the wes... more More than 15 years of field and laboratory investigations on samples from Terre Adélie to the western part of George V th Land (135 to 146°E) during the GEOLETA program allow a reassessment of the Terre Adélie Craton (TAC) geology. The TAC represents the largest exposed fragment of the East Antarctic Shield preserved from both Grenville and Ross tectono-metamorphic events.
Geological Society, London, Special Publications, 2015
ABSTRACT Based on new structural and petrological investigations, we present two crustal-scale cr... more ABSTRACT Based on new structural and petrological investigations, we present two crustal-scale cross-sections of the Kyrgyz South Tien Shan, and correlations of main faults and units between Kyrgyzstan and China. The overall structure corresponds to a doubly-vergent mountain belt. The Kyrgyz and Chinese areas exhibit identical structural and metamorphic histories. To the west, the Atbashi Range comprises high-pressure oceanic and continental units stacked by north-verging thrusts above a low metamorphic accretionary prism. High-pressure (HP) gneisses are bound to their south by a south-dipping detachment exhibiting mantle relicts. The high-pressure oceanic and continental units underwent similar pressure–temperature (P–T ) paths with peak conditions of around 500 8C–20 kbar, followed by rapid exhumation. The overall south-dipping structure and kinematics indicate a south-dipping subduction of the Central Tien Shan Ocean at 320–310 Ma, ending with the docking of the Tarim block to the Kazakh continent. To the east, the Pobeda Massif shows a narrow push-up structure. A major north-vergent thrust exhumes deep-crustal-level granulites, constituting the highest summits, which were thrust towards the north onto low-grade Devonian–Carboniferous schists. The southern part of South Tien Shan is made up of a south-verging thrust stack that formed later during ongoing convergence, reactivated throughout post-30 Ma phases.
Age constraints on the protoliths, deformation, metamorphism and melting events are key parameter... more Age constraints on the protoliths, deformation, metamorphism and melting events are key parameters when correlating different continental lithospheric remnants among each other and disentangling their evolution within large-scale orogens. In situ U-Th-Pb chemical dating on monazites using Electron Probe Micro-Analyser (EPMA) has been performed on eight samples throughout the Variscan Maures-Tanneron massif (SE France) in order to date the medium to high-tectonothermal events related to the Variscan orogeny. Results indicate a polyphased crustal evolution : (i) U-Th-Pb ages obtained in polygenetic monazite grain cores gave inherited Upper Ordovician (456 ± 11 Ma) age, highlighting the large scale occurrence of the Ordovician mag-matic activity in the North Gondwanian margin. An Early Devonian (404 ± 10 Ma) age may date a protolith emplace-ment related to calc-alkaline supra-subduction magmatism or could be associated to an early medium-grade metamorphism, prior to collisional stage. ...
Permian-Triassic and Late Cretaceous accretionary complexes, ascribed to the consumption of two d... more Permian-Triassic and Late Cretaceous accretionary complexes, ascribed to the consumption of two distinct oceans, the Paleo-and Neo-Tethys, are exposed over extensive areas in the Eastern Mediterranean region. However, a separating continental ribbon, the so-called Cimmeride continent, between the Paleo-and Neo-Tethys during early Mesozoic time cannot be defi ned. Here we report a previously unknown Early Jurassic metamorphic oceanic accretionary complex and ophiolite from northeast Turkey, bounded by oceanic accretionary complexes of Permian-Triassic and Late Cretaceous age to the north and the south, respectively, without a continental domain in between. This special tectonic position and widespread coexistence of Permian-Triassic and Late Cretaceous accretionary complexes alongside the Izmir-Ankara-Erzincan suture imply that (1) the southern margin of Laurasia in the eastern Mediterranean region grew by episodic accretionary processes from late Paleozoic to end-Mesozoic time without involvement of a Cimmerian continental ribbon, and (2) the Paleo-Tethys and northern branch of the Neo-Tethys were not distinct oceans in the Eastern Mediterranean region.
We have estimated recent river incision rates using the in situ-produced 36 Cl cosmogenic nuclide... more We have estimated recent river incision rates using the in situ-produced 36 Cl cosmogenic nuclide concentrations. The target site consists of a~25 m high vertical profile along a polished river cliff located in Jurassic limestones in the Vésubie catchment area, in the southern French Alps. The 36 Cl exposure ages of the sampled river polished surface range from 3 to 14 ka, i.e., after the Last Glacial Maximum. Our data suggest as a first approximation a linear age/height relationship and lead to a mean incision rate of 2.2 mm a À1 over the last 14 ka. More precisely, incision rates are characterized by two peaks reaching~2 and 4-5 mm a À1 at 4-5 ka and 11-12 ka, respectively, separated by a period experiencing a lower incision rate (~1 mm a À1 ). A chi-plot of the river longitudinal profile suggests that on the long term, the river is close to equilibrium conditions with a concavity index of 0.475. The evolution of the Vésubie River longitudinal profile over a time period of 2 Ma based on the stream power law of river incision was then modeled with varying erodibility coefficients and uplift rates ranging from 0.5 to 2 mm a À1 . The best fitting models yield erodibility coefficient values ranging from 2.5 to 9.0 × 10 À6 m À0.475 a À1 for the considered uplift rates. For long-term uplift rates lower than 2 mm a À1 , an increase of the erodibility coefficient during the last 16 ka, with two peaks at 11-12 and 4-5 ka, is necessary to precisely match the observed incision rates and is interpreted as resulting from recent climatic changes. These variations do not strongly affect the general shape of the river profile and suggest that the measured short-term incision rate is dominated by a climatic signal, which does not preclude the possible role of tectonic uplift.
ABSTRACT In the South Tien Shan range (Kyrgyzstan), the Late Paleozoic geodynamic evolution remai... more ABSTRACT In the South Tien Shan range (Kyrgyzstan), the Late Paleozoic geodynamic evolution remains debated especially to the west of the Talas-Fergana fault (TFF) fault where suture-related high-pressure (HP) rocks are scarce. We provide new petrological and geochronological data on garnet amphibolites from the Chatkal range, to the west of the TFF, northwest of the South Tien Shan suture. These rocks are retrogressed eclogites. We used a micro-mapping approach combined with forward modelling and empirical thermobarometry to decipher the P-T path of these amphibolitized eclogites. The metamorphic peak conditions culminated at 490 ± 50 °C and 18.5 ± 2 kbar and were followed by higher temperature retrogression (∼ 560 °C at 11 to 7 kbar). In order to constrain the age of the HP stage, we dated allanite crystals texturally coeval to the HP mineral assemblage. Allanite grains dated in-situ with a U-Pb LA-ICPMS methodology yield an age of 301 ± 15 Ma. Compared with previously published data for the east of the TFF, these P-T constraints allow improving the understanding of the Late Paleozoic geodynamic evolution of the South Tien Shan. To the east of TFF, the Turkestan Ocean closed around 320 Ma with the collision of the Tarim Craton with the Kazakh microcontinent. To the west of TFF, the Turkestan Ocean closed around 300 Ma, when the Alai block collided with the Kazakh microcontinent. This later collision involved nappe-stacking and intense subvertical folding in the western South Tien Shan. This complex folding explains the S-shape of the suture to the west of the TFF that cannot be observed in the eastern part. These new data allow us to propose a distinct tectonic evolution of the two sides of the TFF, which suggests that this fault was a major transform fault before being a strike-slip intra-continental fault.
The ophiolites of Amasia in the northwestern part of the Sevan-Akera suture zone (Lesser Caucasus... more The ophiolites of Amasia in the northwestern part of the Sevan-Akera suture zone (Lesser Caucasus, NW Armenia) correspond to a well-preserved example of a major obduction of oceanic lithosphere over the South Armenian continental block. Our mapping evidenced a series of (1) un-metamorphosed gabbroic oceanic crust, (2) serpentinites and a greenschist grade tectonic mélange composed of deformed pillow-basalts, radiolarites and cherts, and a basal slice of garnet amphibolites bearing similar compositional features as the ophiolite. These units are sliced and deformed by post-Eocene thrusting related to the shortening of the suture zone after the collision of the South Armenian Block. 40 Ar/ 39 Ar dating on gabbro amphiboles yielded an age of 176 ± 8 Ma. This age and geochemical composition of ophiolite rocks are similar to those of other ophiolite outcrops in Armenia. Structural and mineralogical analysis undertaken on the garnet amphibolites suggest it to represent the obducted ophiolite metamorphic sole, deformed at high temperature and intermediate pressure (P = 6-7 kbar, T = 630°C). 40 Ar/ 39 Ar dating on amphiboles yielded an age of 91.8 ± 3 Ma, similar to the paleontological age of nannofossils sampled in the frontal flysh related to obduction in Vedi. All these data are in agreement with the presence of a unique ophiolite nappe originating from a Jurassic intra-oceanic back-arc basin, obducted onto the Armenian microblock at c. 92 Ma.
The Roquebrune-Cap Martin basin (RCMB), developed along the eastern rim of the Nice arc, represen... more The Roquebrune-Cap Martin basin (RCMB), developed along the eastern rim of the Nice arc, represents an exclusive sedimentary marker constraining the timing of the deformation in the Nice arc (southern Subalpine chain) during Miocene times. Structural and sedimentological analyses as well as 3D geometrical modeling of the RCMB revealed morphological, structural and sedimentological features characterizing an active tectonic control of the sedimentary infills and the basin development. Structural and microstructural analyses along the eastern boundary of the Nice arc evidenced a N-S left-lateral strike-slip 'en echelon' faults system named Mont Gros-St Agnès Castillon relayed by the Biancon E-W thrusts and sheets. The formation of the RCMB appears to be genetically linked to these strike-slip 'en échelon' faults. Such characteristics include the presence of the Mont Gros strike-slip fault structural high relief bounding the RCMB to the West, the West-East asymmetry of the sedimentary infill with a laterally transition facies from breccias directly below the fault relief to conglomerates and sandstones in the central part of the basin and the presence of mass wasting in all structural levels of the basin. The onset and the evolution of the basin were driven by transpresssive tectonics, generating a deep and narrow tectonic depression, bounded by steep tectonically controlled slopes. The transpresssive character of the eastern Nice arc boundary where the syn-tectonic RCMB is hosted, accommodate a general southward translation of the Nice arc in response to a N-S shortening regime. The sedimentological and previous paleontological analyses suggest that the activity of the eastern Nice arc transpresssive boundary generating the RCMB and thus the southward motion of the Nice arc, started during the Early Miocene (Aquitanian), continuing through the Late Miocene (Tortonian).The style and the timing of the syn-sedimentary deformation of the Nice arc is coherent in space and time with the one affecting the Digne and Castellane arc.
Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones i... more Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones in the region suggest that shallow seismicity may be expressed by low magnitude (Mw < 4) seismic swarms. Deformation of pebbles occurs mainly by pressure dissolution. Pebbles show a bimodal distribution, explained by parallelisation with the two fault strands, which suggests rare seismic unloading and long-lasting creeping processes. Geometrical 3D analysis shows the formation and migration of a Plio-Quaternary basin about 500 metres East of the main fault system together with folding and tilting of the post- Messinian Pliocene molasse. Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones in the region suggest that shallow seismicity may be expressed by low magnitude (Mw < 4) seismic swarms. Deformation of pebbles occurs mainly by pressure dissolution. Pebbles show a bimodal distribution, explained by parallelisation with the two fault stra...
The kinematics of the collision in Western Alps are investigated through five balanced cross sect... more The kinematics of the collision in Western Alps are investigated through five balanced cross sections of the whole external domain from the Oisans to the Mont Blanc massif. These cross sections were built using published data for the Jura and subalpine fold-and-thrust belts and new structural and field analysis for the External Crystalline Massifs. Five units are defined: the sedimentary nappes from innermost parts of the external zone (e.g., ultra-Dauphinois/Helvetic), the crystalline units with their dysharmonically folded cover (e.g., Morcles nappe), sedimentary nappes over the frontal parts of the crystalline massifs (the Aravis-Granier unit), the subalpine belts (e.g., Vercors, Chartreuse, Bauges, and Bornes), and the Jura. Except for the ultra-Dauphinois nappes, the shortening, including the cover shortening, always corresponds to basement shortening. The total amount of shortening increases from south (28 km, 20%) to north (66 km, 27%). Moreover, the shortening is slightly older in the south than in the north; deepwater turbidites (flysch) and shallow marine to freshwater clastics (molasse) basins are more developed in the north; pressure and temperature conditions are higher in the north; the average uplift rates are about 3 times higher in the north and more localized in space. We propose that these differences are due to along-strike variations in the structure of the European continental margin inherited from Mesozoic times. We then build five palinspastic maps: one at Cretaceous times showing the inherited European Mesozoic margin structure and four from Priabonian to upper Miocene times showing the collision kinematics and the related rotation of Adria.
More than 15 years of field and laboratory investigations on samples from Terre Adélie to the wes... more More than 15 years of field and laboratory investigations on samples from Terre Adélie to the western part of George V th Land (135 to 146°E) during the GEOLETA program allow a reassessment of the Terre Adélie Craton (TAC) geology. The TAC represents the largest exposed fragment of the East Antarctic Shield preserved from both Grenville and Ross tectono-metamorphic events.
Geological Society, London, Special Publications, 2015
ABSTRACT Based on new structural and petrological investigations, we present two crustal-scale cr... more ABSTRACT Based on new structural and petrological investigations, we present two crustal-scale cross-sections of the Kyrgyz South Tien Shan, and correlations of main faults and units between Kyrgyzstan and China. The overall structure corresponds to a doubly-vergent mountain belt. The Kyrgyz and Chinese areas exhibit identical structural and metamorphic histories. To the west, the Atbashi Range comprises high-pressure oceanic and continental units stacked by north-verging thrusts above a low metamorphic accretionary prism. High-pressure (HP) gneisses are bound to their south by a south-dipping detachment exhibiting mantle relicts. The high-pressure oceanic and continental units underwent similar pressure–temperature (P–T ) paths with peak conditions of around 500 8C–20 kbar, followed by rapid exhumation. The overall south-dipping structure and kinematics indicate a south-dipping subduction of the Central Tien Shan Ocean at 320–310 Ma, ending with the docking of the Tarim block to the Kazakh continent. To the east, the Pobeda Massif shows a narrow push-up structure. A major north-vergent thrust exhumes deep-crustal-level granulites, constituting the highest summits, which were thrust towards the north onto low-grade Devonian–Carboniferous schists. The southern part of South Tien Shan is made up of a south-verging thrust stack that formed later during ongoing convergence, reactivated throughout post-30 Ma phases.
Age constraints on the protoliths, deformation, metamorphism and melting events are key parameter... more Age constraints on the protoliths, deformation, metamorphism and melting events are key parameters when correlating different continental lithospheric remnants among each other and disentangling their evolution within large-scale orogens. In situ U-Th-Pb chemical dating on monazites using Electron Probe Micro-Analyser (EPMA) has been performed on eight samples throughout the Variscan Maures-Tanneron massif (SE France) in order to date the medium to high-tectonothermal events related to the Variscan orogeny. Results indicate a polyphased crustal evolution : (i) U-Th-Pb ages obtained in polygenetic monazite grain cores gave inherited Upper Ordovician (456 ± 11 Ma) age, highlighting the large scale occurrence of the Ordovician mag-matic activity in the North Gondwanian margin. An Early Devonian (404 ± 10 Ma) age may date a protolith emplace-ment related to calc-alkaline supra-subduction magmatism or could be associated to an early medium-grade metamorphism, prior to collisional stage. ...
Permian-Triassic and Late Cretaceous accretionary complexes, ascribed to the consumption of two d... more Permian-Triassic and Late Cretaceous accretionary complexes, ascribed to the consumption of two distinct oceans, the Paleo-and Neo-Tethys, are exposed over extensive areas in the Eastern Mediterranean region. However, a separating continental ribbon, the so-called Cimmeride continent, between the Paleo-and Neo-Tethys during early Mesozoic time cannot be defi ned. Here we report a previously unknown Early Jurassic metamorphic oceanic accretionary complex and ophiolite from northeast Turkey, bounded by oceanic accretionary complexes of Permian-Triassic and Late Cretaceous age to the north and the south, respectively, without a continental domain in between. This special tectonic position and widespread coexistence of Permian-Triassic and Late Cretaceous accretionary complexes alongside the Izmir-Ankara-Erzincan suture imply that (1) the southern margin of Laurasia in the eastern Mediterranean region grew by episodic accretionary processes from late Paleozoic to end-Mesozoic time without involvement of a Cimmerian continental ribbon, and (2) the Paleo-Tethys and northern branch of the Neo-Tethys were not distinct oceans in the Eastern Mediterranean region.
We have estimated recent river incision rates using the in situ-produced 36 Cl cosmogenic nuclide... more We have estimated recent river incision rates using the in situ-produced 36 Cl cosmogenic nuclide concentrations. The target site consists of a~25 m high vertical profile along a polished river cliff located in Jurassic limestones in the Vésubie catchment area, in the southern French Alps. The 36 Cl exposure ages of the sampled river polished surface range from 3 to 14 ka, i.e., after the Last Glacial Maximum. Our data suggest as a first approximation a linear age/height relationship and lead to a mean incision rate of 2.2 mm a À1 over the last 14 ka. More precisely, incision rates are characterized by two peaks reaching~2 and 4-5 mm a À1 at 4-5 ka and 11-12 ka, respectively, separated by a period experiencing a lower incision rate (~1 mm a À1 ). A chi-plot of the river longitudinal profile suggests that on the long term, the river is close to equilibrium conditions with a concavity index of 0.475. The evolution of the Vésubie River longitudinal profile over a time period of 2 Ma based on the stream power law of river incision was then modeled with varying erodibility coefficients and uplift rates ranging from 0.5 to 2 mm a À1 . The best fitting models yield erodibility coefficient values ranging from 2.5 to 9.0 × 10 À6 m À0.475 a À1 for the considered uplift rates. For long-term uplift rates lower than 2 mm a À1 , an increase of the erodibility coefficient during the last 16 ka, with two peaks at 11-12 and 4-5 ka, is necessary to precisely match the observed incision rates and is interpreted as resulting from recent climatic changes. These variations do not strongly affect the general shape of the river profile and suggest that the measured short-term incision rate is dominated by a climatic signal, which does not preclude the possible role of tectonic uplift.
ABSTRACT In the South Tien Shan range (Kyrgyzstan), the Late Paleozoic geodynamic evolution remai... more ABSTRACT In the South Tien Shan range (Kyrgyzstan), the Late Paleozoic geodynamic evolution remains debated especially to the west of the Talas-Fergana fault (TFF) fault where suture-related high-pressure (HP) rocks are scarce. We provide new petrological and geochronological data on garnet amphibolites from the Chatkal range, to the west of the TFF, northwest of the South Tien Shan suture. These rocks are retrogressed eclogites. We used a micro-mapping approach combined with forward modelling and empirical thermobarometry to decipher the P-T path of these amphibolitized eclogites. The metamorphic peak conditions culminated at 490 ± 50 °C and 18.5 ± 2 kbar and were followed by higher temperature retrogression (∼ 560 °C at 11 to 7 kbar). In order to constrain the age of the HP stage, we dated allanite crystals texturally coeval to the HP mineral assemblage. Allanite grains dated in-situ with a U-Pb LA-ICPMS methodology yield an age of 301 ± 15 Ma. Compared with previously published data for the east of the TFF, these P-T constraints allow improving the understanding of the Late Paleozoic geodynamic evolution of the South Tien Shan. To the east of TFF, the Turkestan Ocean closed around 320 Ma with the collision of the Tarim Craton with the Kazakh microcontinent. To the west of TFF, the Turkestan Ocean closed around 300 Ma, when the Alai block collided with the Kazakh microcontinent. This later collision involved nappe-stacking and intense subvertical folding in the western South Tien Shan. This complex folding explains the S-shape of the suture to the west of the TFF that cannot be observed in the eastern part. These new data allow us to propose a distinct tectonic evolution of the two sides of the TFF, which suggests that this fault was a major transform fault before being a strike-slip intra-continental fault.
The ophiolites of Amasia in the northwestern part of the Sevan-Akera suture zone (Lesser Caucasus... more The ophiolites of Amasia in the northwestern part of the Sevan-Akera suture zone (Lesser Caucasus, NW Armenia) correspond to a well-preserved example of a major obduction of oceanic lithosphere over the South Armenian continental block. Our mapping evidenced a series of (1) un-metamorphosed gabbroic oceanic crust, (2) serpentinites and a greenschist grade tectonic mélange composed of deformed pillow-basalts, radiolarites and cherts, and a basal slice of garnet amphibolites bearing similar compositional features as the ophiolite. These units are sliced and deformed by post-Eocene thrusting related to the shortening of the suture zone after the collision of the South Armenian Block. 40 Ar/ 39 Ar dating on gabbro amphiboles yielded an age of 176 ± 8 Ma. This age and geochemical composition of ophiolite rocks are similar to those of other ophiolite outcrops in Armenia. Structural and mineralogical analysis undertaken on the garnet amphibolites suggest it to represent the obducted ophiolite metamorphic sole, deformed at high temperature and intermediate pressure (P = 6-7 kbar, T = 630°C). 40 Ar/ 39 Ar dating on amphiboles yielded an age of 91.8 ± 3 Ma, similar to the paleontological age of nannofossils sampled in the frontal flysh related to obduction in Vedi. All these data are in agreement with the presence of a unique ophiolite nappe originating from a Jurassic intra-oceanic back-arc basin, obducted onto the Armenian microblock at c. 92 Ma.
The Roquebrune-Cap Martin basin (RCMB), developed along the eastern rim of the Nice arc, represen... more The Roquebrune-Cap Martin basin (RCMB), developed along the eastern rim of the Nice arc, represents an exclusive sedimentary marker constraining the timing of the deformation in the Nice arc (southern Subalpine chain) during Miocene times. Structural and sedimentological analyses as well as 3D geometrical modeling of the RCMB revealed morphological, structural and sedimentological features characterizing an active tectonic control of the sedimentary infills and the basin development. Structural and microstructural analyses along the eastern boundary of the Nice arc evidenced a N-S left-lateral strike-slip 'en echelon' faults system named Mont Gros-St Agnès Castillon relayed by the Biancon E-W thrusts and sheets. The formation of the RCMB appears to be genetically linked to these strike-slip 'en échelon' faults. Such characteristics include the presence of the Mont Gros strike-slip fault structural high relief bounding the RCMB to the West, the West-East asymmetry of the sedimentary infill with a laterally transition facies from breccias directly below the fault relief to conglomerates and sandstones in the central part of the basin and the presence of mass wasting in all structural levels of the basin. The onset and the evolution of the basin were driven by transpresssive tectonics, generating a deep and narrow tectonic depression, bounded by steep tectonically controlled slopes. The transpresssive character of the eastern Nice arc boundary where the syn-tectonic RCMB is hosted, accommodate a general southward translation of the Nice arc in response to a N-S shortening regime. The sedimentological and previous paleontological analyses suggest that the activity of the eastern Nice arc transpresssive boundary generating the RCMB and thus the southward motion of the Nice arc, started during the Early Miocene (Aquitanian), continuing through the Late Miocene (Tortonian).The style and the timing of the syn-sedimentary deformation of the Nice arc is coherent in space and time with the one affecting the Digne and Castellane arc.
Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones i... more Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones in the region suggest that shallow seismicity may be expressed by low magnitude (Mw < 4) seismic swarms. Deformation of pebbles occurs mainly by pressure dissolution. Pebbles show a bimodal distribution, explained by parallelisation with the two fault strands, which suggests rare seismic unloading and long-lasting creeping processes. Geometrical 3D analysis shows the formation and migration of a Plio-Quaternary basin about 500 metres East of the main fault system together with folding and tilting of the post- Messinian Pliocene molasse. Discontinuous fracturation and comparison with seismic monitoring on similar active fault zones in the region suggest that shallow seismicity may be expressed by low magnitude (Mw < 4) seismic swarms. Deformation of pebbles occurs mainly by pressure dissolution. Pebbles show a bimodal distribution, explained by parallelisation with the two fault stra...
The kinematics of the collision in Western Alps are investigated through five balanced cross sect... more The kinematics of the collision in Western Alps are investigated through five balanced cross sections of the whole external domain from the Oisans to the Mont Blanc massif. These cross sections were built using published data for the Jura and subalpine fold-and-thrust belts and new structural and field analysis for the External Crystalline Massifs. Five units are defined: the sedimentary nappes from innermost parts of the external zone (e.g., ultra-Dauphinois/Helvetic), the crystalline units with their dysharmonically folded cover (e.g., Morcles nappe), sedimentary nappes over the frontal parts of the crystalline massifs (the Aravis-Granier unit), the subalpine belts (e.g., Vercors, Chartreuse, Bauges, and Bornes), and the Jura. Except for the ultra-Dauphinois nappes, the shortening, including the cover shortening, always corresponds to basement shortening. The total amount of shortening increases from south (28 km, 20%) to north (66 km, 27%). Moreover, the shortening is slightly older in the south than in the north; deepwater turbidites (flysch) and shallow marine to freshwater clastics (molasse) basins are more developed in the north; pressure and temperature conditions are higher in the north; the average uplift rates are about 3 times higher in the north and more localized in space. We propose that these differences are due to along-strike variations in the structure of the European continental margin inherited from Mesozoic times. We then build five palinspastic maps: one at Cretaceous times showing the inherited European Mesozoic margin structure and four from Priabonian to upper Miocene times showing the collision kinematics and the related rotation of Adria.
Uploads
Papers by yann Rolland