Active tectonics of the Burma region analysed by kinematic inversion of relative motion data

Abstract

The Burma terrane is caught in between the hyper-obliquely subducting rigid Indian plate in the West and the Eurasian plate and the Sunda plate in the North- and South-East respectively. As a result, the sandwiched Burma terrane is expected to undergo internal deformation. Due to the obliquity of this subducting Indian plate the Burma slab is hypothesised to be subjected to (mainly) trench-parallel slab dragging. We would like to asses the current geodynamic setting of the Burma slab in the context of India-Eurasia convergence and the motion of the Burma slab and its potential indentation with Eurasia in the Eastern Syntaxis expressed in the deformation field of the crust. For this assesment we have combined GPS data from 1371 stations and applied the Spakman-Nyst method to estimate a deformation field for the Burma region. Our preferred model relies on both, fault slip and continuous deformation. Our model shows significant fault slip on the Sagaing fault and the Rakhine-Bangladesh megathrust with a strain rate in the order of 1E-7/y along the main frontal thrust and at the northern part of the Rakhine-Bangladesh megathrust. A clockwise rotation of up to 5.7\degree/my is found for North Burma. Our results suggest uplift in the Himalayas and in the Indo-Burman ranges due to active convergence between both India-Eurasia and India-Burma, crustal thinning across the central Tibetan plateau, and NE dragging of the Burma plate by the subducting Indian slab driving plate collision and the CW rotation of the Burma plate.