| Summary: | Myanmar occupies a complex region in the active Indo-Burma subduction system. To illuminate the upper 10 km crustal structure of central Myanmar and obtain new insight into the subduction system, we jointly use P-wave polarizations and receiver functions (RFs) to construct a high-resolution VS profile based on a Bayesian Markov chain Monte Carlo approach. This obtained profile clearly delineates six tectonic units and their boundaries, including the Indo-Burman ranges (IBR), the IBR-fore-arc basin boundary, the fore-arc basin, the volcanic arc, the back-arc basin, and the Sunda plate. The Sunda plate has relatively higher upper crustal VS ( >3.0 km/s) and thinner sedimentary cover ( ∼1 km) compared with the Central Myanmar basin in the Burma plate. The fore-arc basin, containing thick sediments ( >10 km), and the back-arc basin, with thinner sediments ( ∼1-6 km), are separated by a region with higher VS ( ∼3.0 km/s), which represents crystallized magma beneath the volcanic arc. A narrow zone of relatively high-VS ( ∼2.6-2.7 km/s) ophiolites is situated between the fore-arc basin and the IBR. We also find a narrow zone of high-VS ( ∼2.9 km/s) metamorphic rocks contained within the low-VS (≳2.3 km/s) IBR. This study suggests that the proposing joint inversion of two types of single-station measurements, that is, P-wave polarizations and RFs, can robustly and computationally efficiently image the shallow VS structure and provide a reliable uncertainty estimation.
|
|---|