Recent Mountain Building at the Junction Zone of the Northwestern Caucasus and Intermediate Kerch–Taman Region, Russia

Abstract

The recent evolution of the marginal segment of the Northwestern Caucasus orogen at its junction with the Kerch–Taman periclinal trough has been studied. Geomorphological analysis included geological and tectonophysical data and digital elevation models. The Northwestern Caucasus fault–fold morphostructures extend westward to the Crimean mountain structure, in the intermediate Kerch–Taman region, developing in a uniform regional compression setting. The prevailing direction of horizontal compression changed from NE in the Northwestern Caucasus to N–S in the Taman region, resulting in reorientation of the axes of fold morphostructures and geophysical anomalies from NW to EW. The compression vectors separated in the Pliocene–Quaternary. The NE-trending pre-Pliocene fault structures in this area were replaced by the N–S-trending Anapa–Dzhiginka and Abrau active fault zones. As follows from comparison of the Abrau and Anapa–Dzhiginka zones, faulting in Abrau zone became more dynamic in the Pliocene–Quaternary; we revealed clear signs of normal faulting with a vertical offset of 500‒600 m in the Abrau zone during this stage. The Abrau zone is the western boundary zone of the Greater Caucasus. The possible reasons for the restructuring of the regional structural geometry and lateral transition activity of faults transverse to the Northwestern Caucasus orogen are considered.