Role of transverse strike-slip faults in the structure of the Karpinsky Ridge and their kinematics

Abstract

The segmented structure of the Karpinsky Ridge is determined by NE-trending transverse strikeslip faults with offsets of approximately 30–40 km. The newly recognized Pribrezhny Fault and the well-known Agrakhan Fault are the largest. A new correlation scheme for structural elements of the ridge’s eastern segment and its underwater continuation is proposed with account of offset along the Pribrezhny Fault. According to this scheme, the Semenovsky Trough rather than the Dzhanai Trough is an onshore continuation of the underwater Zyudevsky Trough. The uplift located south of the Zyudevsky Trough is correlated with the Promyslovy-Tsubuk Swell offset along the Pribrezhny Fault. In turn, this uplift is displaced along the right-lateral strike-slip fault that coincides with the Agrakhan Fault. The transverse faults were formed during the Early Permian collision related to the closure of the basin, which was presumably underlain by the oceanic crust. The faults were active during the Early Triassic rifting and Late Triassic inversion. Judging from the map of the surface of the Maikop sediments, the Agrakhan Fault does not cross the Terek-Caspian Trough. Bending arcwise, the fault joins a system of right-lateral strike-slip faults that border the Daghestan Wedge in the east. A system of rightlateral strike-slip faults may also be traced along the western coast of the Caspian Sea. The Agrakhan Fault as a northern element of this system functioned mostly in the Late Paleozoic-Early Mesozoic in connection with the formation of the fold-thrust structure of the Karpinsky Ridge. In the east the faults of the southern segment bound the Caucasus syntaxis of the Alpine Belt; they have retained their activity to the present day.