0000000000083029

AUTHOR

Patrick Monié

Early exhumation of high-pressure rocks in extrusion wedges: Cycladic blueschist unit in the eastern Aegean, Greece, and Turkey

Structural, metamorphic, and geochronologic work shows that the Ampelos/Dilek nappe of the Cycladic blueschist unit in the eastern Aegean constitutes a wedge of high-pressure rocks extruded during early stages of orogeny. The extrusion wedge formed during the incipient collision of the Anatolian microcontinent with Eurasia when subduction and deep underthrusting ceased and the Ampelos/Dilek nappe was thrust southward over the greenschist-facies Menderes nappes along its lower tectonic contact, the Cycladic-Menderes thrust, effectively cutting out a ∼30- to 40-km-thick section of crust. The upper contact of the Ampelos/Dilek extrusion wedge is the top-to-the-NE Selcuk normal shear zone, alon…

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Late Palaeozoic to Mesozoic kinematic history of the Talas-Ferghana strike-slip Fault (Kyrgyz West Tianshan) as revealed by 40Ar/39Ar dating of syn-kinematic white mica

International audience; The NW-trending Talas-Ferghana Fault (TFF) in Kyrgyzstan, Central Asia, is one of the largest intracontinental strike-slip faults in the world. It extends over a distance of more than 2000 km from southern Tourghai to western Tarim and exhibits a maximum dextral offset of ∼200 km during the late Palaeozoic to present. The history of the fault provides important insights for the understanding of the evolution of southern Central Asia but remains poorly constrained due to lack of reliable geochronological data. We present new Ar-Ar ages and structural data from the Kyrgyz West Tianshan, that elucidate the kinematic history of the TFF in the Palaeozoic and Mesozoic. 40A…

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Textural-chemical changes and deformation conditions registered by phyllosilicates in a fault zone (Pic de Port Vieux thrust, Pyrenees)

International audience; Synkinematic phyllosilicates in fault zones can be used to deduce the deformation mechanisms and the conditions of fault activity, as their chemical composition, crystal structure and texture can record the different stages of deformation and fluid-rock interactions. The Pic de Port Vieux, a second-order thrust related to the major Gavarnie thrust in the southern central part of the Pyrenees Axial Zone, juxtaposes Triassic pelites of the hanging wall and Cretaceous limestones of the footwall. In order to investigate the mineralogical and geochemical changes and constrain the deformation conditions of thrusting, characterization of phyllosilicates was performed along …

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The extensional Messaria shear zone and associated brittle detachment faults, Aegean Sea, Greece

Structural, thermochronological and metamorphic data are used to elucidate the tectonic nature and evolution of the ductile extensional Messaria shear zone and the associated brittle Messaria and Fanari detachment faults, which exhumed their footwall from mid-crustal depths on the island of Ikaria in the Aegean. Thermobarometric data indicate that the Messaria shear zone formed at 350–>400 °C and 3–4 kbar (i.e. at a depth of c . 15 km). Normal faulting was accompanied by the intrusion of two granites, which together with the thermobarometric data indicate a relatively high thermal field gradient of 25–35 °C km −1 . Zircon and apatite fission-track and apatite (U–Th)/He ages demonstrate rapi…

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The extensional Messaria shear zone and associated brittle detachment faults, Aegean Sea, Greece

Structural, thermochronological and metamorphic data are used to elucidate the tectonic nature and evolution of the ductile extensional Messaria shear zone and the associated brittle Messaria and Fanari detachment faults, which exhumed their footwall from mid-crustal depths on the island of Ikaria in the Aegean. Thermobarometric data indicate that the Messaria shear zone formed at 350–>400 °C and 3–4 kbar (i.e. at a depth of c. 15 km). Normal faulting was accompanied by the intrusion of two granites, which together with the thermobarometric data indicate a relatively high thermal field gradient of 25–35 °C km−1. Zircon and apatite fission-track and apatite (U–Th)/He ages demonstrate rapi…

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