Cenozoic Wedge Tectonics as a Crustal Thickening Mechanism for the Min Shan, Eastern Tibetan Plateau

Abstract

The Tibetan Plateau records active deformation during the ongoing India‐Asia collision, yet the mechanisms for its crustal thickening and surface uplift remain debated. In eastern Tibet, uplift of the Min Shan is attributed to either mid‐crustal channel flow or localized slip along thrust faults, but neither model adequately explains the combination of high topography, eastward‐decreasing slip rates along major strike‐slip faults, and uplift of the Min Shan in the footwall of the Minjiang thrust fault. We integrate new geologic mapping, structural data, and reinterpretation of a 55‐km‐long seismic reflection profile across the western Min Shan to investigate the mechanism of its uplift. Our mapping and seismic reflection interpretations reveal a west‐vergent tectonic wedge bounded by an east‐dipping thrust ramp beneath the Min Shan and west‐dipping roof thrusts of the Minjiang fault to the west. Tectonic wedging explains uplift of the Min Shan, development of the wedge‐top Roergai Basin, and deflection of the Yellow River within the basin. Furthermore, we newly document distributed conjugate strike‐slip faults across the eastern plateau interior that accommodate east‐west shortening and explain the eastward decrease in slip rates along major strike‐slip faults. Our tectonic wedge interpretation for the uplift of the Min Shan challenges models of channel flow in this region while the documentation of regionally distributed conjugate strike‐slip faults suggests that rigid block models of eastward extrusion are oversimplified.