The structural framework and recent geodynamics of the Greater Caucasus Meganticlinorium in the light of new data on its deep structure

Abstract

Using the microseismic sounding method (MSM), deep sections along two profiles intersecting the central part of the Greater Caucasus in Ossetia and its northwestern part near the town of Tuapse have been compiled. The revealed heterogeneities of the lithosphere display close relationships to orogenic tectonic deformations and young volcanic activity. Along the profile in the Ossetian sector of the Greater Caucasus, three deep-seated bodies of the Earth’s crust with characteristic properties and morphology have been identified beneath the mountain system. These are a near-vertical low-velocity body and two high-velocity bodies framing the latter in the north and the south. The low-velocity body is primarily situated beneath the axial zone of the Greater Caucasus Meganticlinorium, whereas the high-velocity bodies occur beneath its southern and northern limbs. The persistent horizontal roof of the low-velocity body is traced beneath the entire core of the fold edifice at a depth of approximately 10 km. In the Tuapse sector near the western pericline of the meganticlinorium, the contrast of the low-velocity body is much less pronounced. The most contrasting narrow low-velocity bodies are related to the boundary of the Caucasus (West Kuban) Foredeep with the mountain edifice and the Adygean ledge.