Research

The country of Myanmar, situated to the east of the Indian plate, on the southwestern margin of the Eurasian plate, occupies an important geologic position to understand the tectonic evolution of the Indo-Eurasia collision system. Myanmar is also a country threatened by a high level of seismic hazards with both its economic center (Yangon) and political capital (NayPyiTaw) located on or near the active Sagaing fault. Thus, a better understanding of the lithospheric scale velocity structure of Myanmar could have a major impact in unraveling the regional tectonics, improving the quality of seismological studies (e.g., earthquake hypocenter determinations, focal mechanism inversions, and ground motion simulations), and potentially help to mitigate the seismic hazard and risk in this area.

In this project, we aim to construct high-resolution velocity models beneath Myanmar and surrounding regions, by using data from newly deployed seismic stations. We plan to use a variety of datasets to achieve this goal, including receiver functions, ambient noise, local seismic waves, teleseismic body and surface waves, and etc.

This project is led by Prof. Yixian Xu from Zhejiang University. Cu-Au porphyry ore deposits are typically formed in oceanic or continental arcs above subduction zones and in back-arc extension settings. A recently proposed model suggests that a fertile or refertilized subcontinental lithospheric mantle (SCLM), trans-lithospheric faults, and multi-phase triggered tecto-thermal events are three key factors for the formation of giant Cu-Au porphyry ore deposits. Therefore, a major challenge rises in developing techniques to unravel time evolution and spatial variation of SCLM in trans-lithospheric structural corridors, including to determine the present lithospheric architecture and composition, to reconstruct its ancient tectonic setting, and to trace its deformation history since the formation of the porphyry ore deposit. We propose to use northwestern Tianshan and western Junggar in the Central Asian Orogeny Belt as a field laboratory for its well-known superior Cu-Au accumulation in the Late Paleozoic. We will use local and teleseismic earthquake body-wave travel-time tomography, earthquake and noise-based surface waves tomography, P- and S-wave receiver function imaging, and magnetotelluric three-dimensional isotropic inversion and anisotropic modeling, to determine the lithospheric architecture and physical properties. We will use the obtained geometry of lithospheric mantle and anisotropies of seismic velocity and conductivity to reveal possible frozen-in lithospheric deformations, distribution of predominant weak and conductive features such as trans-lithospheric shear-zones and magmas. The Late Paleozoic geological evolution of SCLM will be reconstructed by comprehensive analysis of mantle xenoliths, including lithofacies inspection, geochronological dating, and geochemical tracing techniques. Based on these data, we will build a regional model consisting of several key snapshots of SCLM to describe its geodynamic process in relation to the formation of the porphyry Cu-Au ore deposits in the area.