Meso‐Cenozoic Multiple Deformations of the Southern Margin of Sichuan Basin and Their Response to Tectonic Events in East Asia

ABSTRACT Since the Mesozoic, the southern margin of the Sichuan Basin has experienced multiple deformations due to the far‐field effects of geological events, including the westward subduction of the Paleo‐Pacific Plate and the collision between the Indian and Eurasian plates; it serves as a natural laboratory for investigating intracontinental deformation. Through detailed geological surveys, analysis of over 500 vector datasets, and paleostress inversion, we identified three significant deformations in this region during the Meso‐Cenozoic. Low‐temperature thermochronology data constrain the timing of these deformation and cooling‐exhumation events. The first phase occurred during the Late Mesozoic; in the early deformation stage, trough‐like folds developed outside the basin, accompanied by medium‐ to high‐angle SE‐dipping thrust faults in the cores of the anticlines, while a widely developed planar conjugate shear joints formed within the basin. In the later stage of deformation, the NW‐SE compression rotated to N‐S due to boundary fault activation, resulting in the formation of nearly E‐W trending folds within the basin. The deformation was likely induced by multiple NW‐directional detachments and progressive compression in the Xuefeng orogenic belt. The second phase, characterised by NW‐trending box folds and SW‐dipping, moderate‐ to high‐angle thrust faults, took place from the Eocene to early Miocene, induced by compressional forces from the India–Eurasian plate collision, leading to NE‐SW compression and significant exposure in the Dalou and Daliang Mountains, with some involvement of basin strata. The third phase, characterised by NE‐trending tight anticlines and high‐angle reverse faults NW dipping in the core of the anticlines since the mid‐Miocene, is linked to the eastward lateral extrusion of crustal material from the Tibetan Plateau towards the northwest margin of the Sichuan Basin, resulting in strong NW‐SE compression that likely impacts the basin's southern edge. These multiple deformations indicate two major shifts: the transition from the Marginal‐Pacific tectonic domain to the Tethys‐Himalayan domain, and the phased outward expansion of the Himalayan tectonic domain due to changes in the Tibetan Plateau's internal geodynamic setting since the Miocene. Understanding these deformations is crucial for elucidating the mechanisms of intracontinental deformation in the context of plate collision.