East-west crustal structure and“down-bowing”Moho under the northern Tibet revealed by wide-angle seismic profile
作者单位：Department of GeophysicsStanford University
会议名称：《中国科学院地质与地球物理研究所2002学术年会》
会议日期：2002年
学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学]
关 键 词：northern Tibet wide-angle seismic profile P- and S-wave velocity Poisson’s ratio "down-bowing"Moho eastward flow of materials.
摘 要：We recognized 6 sets of reflecting P- and S-wave events from Moho and other nter-faces within the crust,respectively,with the wide-angle seismic data acquired from 510 km-long Selincuo-Ya’anduo profile in the northern Tibet,fitted the observed events with orward modeling,and interpreted crustal structure of P- and S-wave velocities and Poisson’s tiounder the *** results demonstrate that the crustal structure between Yarlungzangbo and angong-Nujiang sutures changes abruptly,and the crust is the thickest at the middle part of the profile with thickness of 80 km or ***down-bowingMoho is the striking feature for the crustal variation along the west-east *** Moho uplifts with steps,and the uplifting rate westward is greater than that *** heterogeneity of P- and S-wave velocities exists both vertically and horizontally,and one lower velocity layer(LVL) exists with the depth range of 27—34 km and the thickness range of 5—7 *** the upper crust,Poisson’s ratio is the lowest at the middle part of the profile;for the lower crust,the Poisson’s ratio at the east segment is lower than that at west segment,which means that the crustal rigidity for the upper crust is different from the lower crust,and the lower crust under the east segment of the profile is more *** infer that the substance in the lower crust endured eastward flow along with the collision between Eurasian and Indian plates,and thedown-bowingMoho is attributable to the multi-phase E-W tectonic processes.