0000000000595491
AUTHOR
Michel Corsini
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…
Zircon and muscovite ages, geochemistry, and Nd-Hf isotopes for the Aktyuz metamorphic terrane: Evidence for an Early Ordovician collisional belt in the northern Tianshan of Kyrgyzstan
International audience; The Aktyuz metamorphic terrane in the Kyrgyz northern Tianshan consists of granitoid gneisses and migmatites with subordinate paragneisses, greenschists, presumed meta-ophiolites, and garnet amphibolite dykes that contain HP eclogite relicts. The gneisses and migmatites were previously considered to be Archaean and Palaeoproterozoic in age on the basis of α-Pb and U-Pb multigrain zircon dating. Zircons from a post-tectonic granite were previously dated at 692 ± 15 Ma, constraining the time of main deformation and metamorphism in the Aktyuz terrane to the Precambrian. The chemical characteristics of most granitoid samples are consistent with melting of chemically evol…
Metamorphic and structural evolution of the Maures-Tanneron massif (SE Variscan chain): evidence of doming along a transpressional margin
AbstractThe Variscan metamorphic and structural evolution of the Maures-Tanneron massif is divided in two main post-collisional phases: (1) a MP-MT regional gradient is developed during nappe-piling process between 350 and 320 Ma, followed by (2) LP-HT regional gradient coeval with doming between 320 and 300 Ma. During this late phase, the tectonic context was dominated by E-W shortening, which produced crustal-scale upright folds and major strike-slip displacement along trans-crustal faults. Symmetric extensional fabrics are observed on the limbs of crustal-scale anticlines, and are ascribed to local accommodation of lower crust exhumation. Heat and magma transfer are allowed by these larg…
Variscan evolution of the Tanneron Massif, SE France, examined through U-Pb monazite ages
The Tanneron massif belongs to the southernmost segment of the Variscan belt in France and is composed of migmatitic orthogneisses and paragneisses cross-cut by a main tonalite–granite complex. Late Carboniferous detrital basins are bounded by north–south-trending ductile to brittle normal faults and delineate three distinct zones. Our new isotope dilution U–Pb monazite dating indicates a pre-Variscan history in the central part of the massif recorded by monazites from an orthogneiss yielding ages from 440 to 410 Ma, whereas monazites from a migmatitic paragneiss record a late Carboniferous high- T event at 317 ± 1 Ma. In the eastern part, a migmatization event is recorded by monazites from…