NORTHERN CAUCASUS BASIN: THERMAL HISTORY AND SYNTHESIS OF SUBSIDENCE MODELS

Abstract

Burial histories of the eastern, central and western parts of the Northern Caucasus basin are reconstructed on the basis of well data and seismic sections. Subsidence began in the Early Triassic after the Late Carboniferous–Permian orogeny. Triassic sediments were mainly removed during Late Triassic–Early Jurassic uplift and erosion. Platform cover began to form in the Middle Jurassic and Albian sediments covered the whole territory of the basin. Thermal modelling shows that Jurassic–Eocene subsidence was mainly controlled by Late Triassic–Early Jurassic intrusive warming. This heating event induced thermal uplift of the whole territory followed by exponentially decelerating subsidence due to cooling of the lithosphere. In the southern areas adjacent to Great Caucasus, subsidence was also affected by Caucasian extensional and compressional events. In the Oligocene–Early Miocene, the eastern and the central basins underwent rapid long wavelength subsidence (Maikopian subsidence). The geodynamic cause of this subsidence is probably associated with the mantle flow appearance after cessation of the Tethyan subduction, due to reequilibration of subducted slab. While in the Late Miocene–Quaternary times, the eastern and the western basins underwent foreland-type asymmetrical subsidence due to loading of the Great Caucasus orogen; the central basin was uplifted. According to flexural modelling, the main component of orogen loading was the lithospheric root load; delamination of the latter under the Central Caucasus caused rapid uplift of the orogen and adjacent basin.