Timing of the initial collision between the Indian and Asian continents

Abstract

There exist three mainstream opinions regarding the timing of the initial collision between the Indian and Eurasian continents, namely, 65±5, 45±5, and 30±5 Ma. Five criteria are proposed for determining which tectonic event was related to the initial collision between India and Asia: the rapid decrease in the rate of plate motion, the cessation of magmatic activity originating from the subduction of oceanic crust, the end of sedimentation of oceanic facies, the occurrence of intracontinental deformation, and the exchange of sediments sourced from two continents. These criteria are used to constrain the nature of these tectonic events. It is proposed that the 65±5 Ma tectonic event is consistent with some of the criteria, but the upshot of this model is that the magmatic activity originating from the Tethyan subduction since the Mesozoic restarted along the southern margin of the Asian continent in this time after a brief calm, implying that the subduction of the Neotethys slab was still taking place. The magmatic activity that occurred along the southern margin of the Asian continent had a 7-Myr break during 72–65 Ma, which in this study is interpreted as having resulted from tectonic transformation from subduction to transform faulting, indicating that the convergence between the Indian and Asian continents was once dominated by strike-slip motion. The 30±5 Ma tectonic event resulted in the uplift of the Tibetan Plateau, which was related to the late stage of the convergence between these two continents, namely, a hard collision. The 45±5 Ma tectonic event is in accordance with most of the criteria, corresponding to the initial collision between these two continents.