The Moho structure beneath the Yarlung Zangbo Suture and its implications: Evidence from large dynamite shots

Abstract

The Yarlung Zangbo Suture (YZS) is the collisional front between the Indian and Eurasian plates. The deep structure beneath the YZS has long been a focus of research. Its particular tectonic location and formation time provide a natural laboratory for the study of ongoing continental collisional processes. Lateral variations in the Moho discontinuity provide evidence of basic processes governing plate tectonic evolution. The depth and geometry of the Moho provides first-order information for restoration of complex geodynamic systems. This paper presents a studying result of the Moho, both adjacent to and beneath the YZS, obtained using five large dynamite shots along two profiles. These five large shots were combined to construct two single-fold profiles (YZS-A and YZS-B) and obtain high-resolution images of the Moho beneath the YZS. Both profiles show that continental crust thickness beneath the YZS is twice the global average of continental crust, and the depth of the Moho along profile YZS-B is deeper than YZS-A. YZS-A (81°E) indicates a relatively flat Moho without offset related to continent-continent convergence beneath the collision zone. Conversely, a Moho structure with offset and overlapping reflections was imaged beneath profile YZS-B (88°E). Significant lateral variations in the geometry of the Moho discontinuity along the YZS may indicate that the Indian lithosphere is thrusting beneath Tibet at a different angle from west to east.