摘要
本文通过对羌塘盆地内49个临时宽频带地震观测台阵数据的接收函数分析,采用H_(-κ)叠加和CCP叠加成像两种方法,获得到了藏北羌塘中部莫霍面深度以及泊松比分布.作为羌塘盆地构造单元的南缘边界,班公湖一怒江缝合带下的Moho存在一个南深北浅、断距约10km的台阶;把羌塘盆地分为两部分的羌塘中央隆起带下存在一个3 km的Moho台阶;北羌塘盆地下的Moho平均深度约为60km,而南羌塘约为63km.羌塘高原下的近水平Moho结构可能是受到印度大陆北向俯冲作用下的青藏高原隆升过程中Moho再均衡所致或者与其构造演化有关.泊松比值具有明显的构造分区特征,如南羌塘下的泊松比平均为0.31,双湖缝合带下的泊松比接近正常值,为0.265,而北羌塘的泊松比平均为0.285.
This study conducted a systematic receiver function analysis using a total of 1291 high signal-to-noise ratio teleseismic traces in the time period of 2009--2010 recorded by 49 stations that were temporarily deployed in the region. A standard H-to stacking method is employed to determine Moho depth from receiver functions, and then CCP stacking image method is used to check continuity of Moho discontinuity. Good coherence of Moho depth in the study with previous seismic results shows the Moho topography beneath the region is reliable, lwo steps oi Moho exist beneath Qiangtang, 10 km Moho offset beneath BNS as the south tectonic boundary of Qiangtang and 3 km offset of Moho beneath central metamorphic belt who divides Qiangtang into South Qiangtang basin with an average Moho depth of 63 km and North Qiangtang basin with Moho depth of 60 km or shallower. Nearly horizontal Moho beneath Qiangtang was probably caused by re-isostatic process resulted from northward subduction and injection of Indian plate. The Poisson＇ s ratio varied with tectonic units, 0.31 in South Qiangtang, 0. 265 in Shuanghu suture zone, and 0. 285 in North Qiangtang, respectively.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第7期2043-2053,共11页
Chinese Journal of Geophysics
基金
国土资源部公益行业基金项目(SinoProbe02,201011042,201011044)
国家自然基金项目(40974060,40774051,41274095)
中国地质科学院地质研究所基本科研基金项目(J1216)联合资助
