TECTONIC STRESSES IN THE CHERSKY FAULT ZONE (BAIKAL RIFT SYSTEM

Abstract

Based on the kinematic and structural-paragenetic approaches, there were performed the reconstructions of tectonic stresses in the Chersky fault zone. Rank analysis as applied to specialized mapping of fault zones was made for heterochronous rock complexes: Paleozoic, Upper Oligocene – Lower Pliocene and Upper Pliocene – Quaternary. There are distinguished three regional stress fields: Pre-Cenozoic compressive stress field with the NW-SE striking principal axis and two Cenozoic tensile stress fields with different axial orientations. The Cenozoic tensile stress field with a sub-meridionally striking minimum compression axis may be an earlier occurrence because it was found to exist in the Paleozoic and Oligocene – Early Pliocene rocks, and the tensile stress field, with the NW-SE axial orientation, may be later occurrence as reconstructed for all rock complexes including Quaternary pebbles. No evidence was found of tectonic shear stresses within the studied segment of the Chersky fault zone. Consideration is being given to probable reasons for the absence of residual shear deformations in the region and to the problems in the study of hierarchy of the upper crustal tectonic stresses.