Microcontinent subduction and S-type volcanism prior to India\u2013Asia collision

Zongyao Yang,Juxing Tang,Xiaoyan Zhao,Fengqin Ran,Shuai Ding,Ying Wang,Xinghai Lang,M. Santosh

doi:10.1038/s41598-021-94492-y

Abstract

Continental crust has long been considered too buoyant to be subducted beneath another continent, although geophysical evidence in collision zones predict continental crust subduction. This is particularly significant where upper continental crust is detached allowing the lower continental crust to subduct, albeit the mechanism of such subduction and recycling of the upper continental crust remain poorly understood. Here, we investigate Paleocene S-type magmatic and volcanic rocks from the Linzizong volcanic succession in the southern Lhasa block of Tibet. These rocks exhibit highly enriched 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb together with depleted 143Nd/144Nd isotope ratios. The geochemical and isotopic features of these rocks are consistent with those of modern upper continental crust. We conclude that these Paleocene S-type volcanic and magmatic rocks originated from the melting of the upper continental crust from microcontinent subduction during the late stage of India–Asia convergence.

Highlights

Continental crust has long been considered too buoyant to be subducted beneath another continent, geophysical evidence in collision zones predict continental crust subduction
The Linzizong volcanic succession (LVS) and the coeval intrusive rocks in southern Tibet, which cover more than 50% of the Gangdese Belt extending E–W for more than 1200 km (Fig. 2A) are prominent markers of the magmatic activity associated with the India–Asia collision[4,5,6,7,8,9]
The geodynamic setting of the Paleocene Dianzhong volcanic and intrusive rocks was either an Andean-type convergent margin formed by the northward subduction of the Neo-Tethys oceanic crust beneath the Lhasa block[19], or a syn-collision orogen formed during the rollback of the Neo-Tethys slab accompanied by crustal melting induced by asthenospheric upwelling and magma m ixing[8,14,15,16,17]

Summary

Introduction

Continental crust has long been considered too buoyant to be subducted beneath another continent, geophysical evidence in collision zones predict continental crust subduction. Delhi Indian plate the S-type magma where we envisage of the subduction of microcontinent during the India–Asia convergence, and that the partial melting of the upper continental crust (UCC) of the subducted microcontinent significantly contributed to the formation of the Paleocene S-type volcanic rocks and granitoids.

Results

Conclusion