A tomography study of the broad-band seismic profiling across Gangdise Block

As the Tibetan Plateau resulted from the direct collision between Indian and Eurasian continents which started about 60 Ma ago, it is regarded as the best stage for studying the continental collision process and perfecting the theory of plate tectonics. As the Gangdise Block (GDS) lies in the frontier of the collision zone, the research on the GDS would be greatly helpful to the understanding of the whole process of the collision and the derived crustal deformation evolution of the Tibetan Plateau. A seismic profiling stretching from the north of Bangong-Nujiang faulted zone to southern Himalayas was performed from September 2011 to September 2012. This profile ran across Bengcuo-Jiali faulted zone, Gangdise Block (GDS), Yarlung Zangbo suture zone and South Tibetan De-collaboration (STD) system. The authors conducted the 2D travel-time residual inversion of the profile using the body wave of natural earthquakes, revealed the deep structural geometry of the study region, and for the first time verified the conclusion about the existence of massive partial-melting layer in the shallow part of GDS. The results obtained by the authors support the metallogenic model that the Jiama porphyry Cu deposit was derived from the magma intrusion in a continental collision environment. The PKP curves depict the Moho pattern of the study area, and determine that the thickest crust lies within 50 km from the north and south sides of the Yarlung Zangbo suture zone. The authors hold that these discoveries and inferences would provide significant information for the study of deep structures of the Tibetan Plateau. ©, 2014, Science Press. All right reserved.