Eastern Himalayan Syntaxis formation and evolution dominated by slab tear of Indian slab

Tectonic syntaxes in continent-continent collision belts are often featured by sharply curving orogenic syntaxis zones. Within and around the plate corners, tectonic mountain building processes and surface processes interact extensively. The formation and evolution of these tectonic syntaxes, namely plate corners, remain debatable. The Eastern Himalayan Syntaxis (EHS), located at the junction of the Himalayan mountain belt, the Tibetan Plateau, and the Indo-Burmese ranges, is a classic region to investigate the significant tectonic feature. In this contribution, based on field-based structure analysis and geochronology within the EHS, eastern Tibet and western Yunnan regions, we suggest a new model for the EHS formation and evolution that is predominantly driven by slab tear of subducted Indian lithosphere. Our investigations reveal that region-scale dextral strike-slip shear zone system, shearing between 30-15 Ma around the EHS region from eastern Tibet to western Yunnan regions, was directly corresponding to slab tear of subducted Indian lithosphere. Within the EHS, conjugated strike-slip shear zones acted ranging from 10-2 Ma or continuous to current day. Our models indicate continuous Cenozoic intracontinental strike-slip shearing indicates a tectonic shift from Tibetan extension to block rotation around the EHS. From 30 to 2 Ma, slab tear, accompanied by clockwise rotation and strike-slip shearing around and within the EHS, suggests a warmer geodynamic setting influenced by hot mantle flow associated with ongoing subduction of the Indian lithosphere. Oligocene-current strike-slip shearing around and within the EHS, linking southwards with the Sagaing Fault, may correspond to the rotation necessary for slab to bend, stretch, and eventually tear beneath the region. Our models also suggest that both giant strike-slip shear system around the EHS, continuous block rotation and syntaxis structure formation are controlled by slab tear of the Indian slab, which is a key tectonic process controlling recent structural and topography development of the Tibetan-Himalayan orogen. The discovered links between syntaxis formation, giant strike-slip shearing, plate rotation and slab tearing suggest that plate corners in collisional orogens may dominate the evolution of the entire orogenic system.