The fault and stress patterns of Western Transbaikalia

Stress patterns are reconstructed for large fault zones and the respective fault-bounded blocks in Western Transbaikalia (southeast of Lake Baikal). The reconstruction is based on analysis of structural measurements combined with slickenside data and earthquake mechanisms. The combination of several methods for stress inversion provides high quality of the results. The inferred diversity of local stress tensors is analyzed in terms of the hierarchy of crustal stresses unevenly distributed in space and time. The tectonic stress fields at the local, subregional, and regional levels result from changes in the magnitude of principal stresses and their respective switch during the evolution of fault zones. The reported regional paleostress reconstructions for rocks of different ages not only have confirmed the sequence of events in the Mesozoic-Cenozoic history of Western Transbaikalia but revealed additionally the previously unknown stress regime of strike-slip which existed there after the closure of the Mongolia-Okhotsk ocean. The heterogeneous patterns of local stress tensors indicate the absence of a single crustal stress field in the region.