Conjugatal extrusion with dextral deformation in the Southeast Tibet: New insight into the Oligo-Miocene deformation in the Southeast Tibet

Abstract

The Southeast Tibet has experienced significant deformation during the Late Cenozoic period, characterized by clockwise block rotation and separated by left-lateral strike-slip faults. Through our new field survey, structural analyses and microstructural observations, we have identified an early phase of ductile shear zones along three major faults: the Anninghe, Jinhe-Jinghe fault and Jinpingshan faults. New geochronological and thermochronological data collected from fault zones and carbonatites associated with a tear fault between two right-lateral oblique faults provides evidences that the slip occurred before ∼30 Ma. These new findings have led to a new conceptual model suggests that these NS-trending right-lateral oblique-slip faults, together with these NW-trending left-lateral strike-slip faults in Southeast Tibet, form a network of large conjugate fractures. The network was formed due to N-NE-trending contraction and played a crucial role in controlling the overall tectonic frame of Southeast Tibet during the Oligocene. By compiling and reviewing previous research with our latest findings, we propose that the region has undergone a transtion from oblique dextral to sinistral shearing since the Oligocene, providing new insights into the tectonic evolution of the East Tibet. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.7262890