Thermal evolution of an intracratonic rift: The Donbas Foldbelt (Ukraine)

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The Ukrainian-Russian Pripyat-Dniepr-Donets basin is a large intracratonic rift structure formed during the Late Devonian. It is situated at the southern margin of the Precambrian East European Craton, adjacent to the Hercynian Tethyan belt in the Black Sea area and the Alpine Caucasus orogen. Its structural evolution is characterized by frequent changes between extensional and compressional settings, and periodically rejuvenated magmatism. The eastern part of the Pripyat-Dniepr-Donets basin - called Donbas foldbelt - is strongly folded and inverted. The exact timing of inversion is still under debate, but may have taken place during a major erosion period in the Permian, or in response to Alpine tectonics during the Late Cretaceous to Early Tertiary. The structure of the Donbas foldbelt was recently investigated by seismic reflectance and refraction in the frame of the international collaborative DOBRE project. In this study, the Donbas foldbelt is used as an example to investigate the evolution and inversion of an intracratonic rift basin. Zircon and apatite fission track analysis, as well as apatite (U-Th)/He analysis will be applied along two profiles; one follows the DOBRE seismic section across strike, transecting the major structural units of the Donbas foldbelt as well as the adjacent Ukrainian shield, the other section follows the former rift axis along strike. The thermochronologic data will be used to (i) relate the thermal evolution of the basin to the structural evolution, as revealed by the seismic profile, and (ii) to reconstruct the thermotectonic evolution with special emphasis to the Permian and Late Cretaceous/Early Tertiary tectonic activity that led to basin inversion.