【摘要】 本文收集了WWSSN台网和我国台网中13个地震台站的长周期地震记录,用140条10—90s瑞利波频散曲线和作者提出的Tarantola-Backus面波频散层析成象方法,作了青藏高原及邻区的速度反演,得出该地区岩石层速度结构的三维图象.结果表明,1.在10—110km深度范围内,速度结构出现与大地构造特征相关的分区性,显示出四个构造单元:青藏块体、柴达木—巴颜喀拉—三江块体、塔里木块体和印度块体.2.高原内部,深度为10—70km内速度较低,莫霍界面呈不对称盆形分布,藏北那曲附近地壳厚度超过70km,高原边缘壳厚为45—50km,90—110km为高速异常,表明高原内部存在上地幔盖层.3.高原北部的班公湖断裂和东部的三江断裂系是该区重要的分界线,是岩石层结构存在明显差异的重要接触部位,可能是冈瓦纳古陆与欧亚古陆的缝合带.4.柴达木—巴颜喀拉—三江块体内部速度分布不均匀,地壳厚度由北向南从45km加深到60km;在深度90—110km存在一低速层.5.塔里木地块内速度随深度均匀增加,从地壳到上地幔110km内没有发现低速层.地壳厚度约50km.更多还原

【Abstract】 Surface wave data, consisting of 140 individual dispersion curves, have been obtained from 13 stations located in and outside of the Qinhai-Tibet region of western China. Tomographic inversion of the data have yeilded a rather detailed structural model (10-110 km depth range) beneath the studied region. The results indicate as follows: (1) The study region consists of four distinct crust-mantle velocity substructures, each of which can be identified with one of the known tectonic units: Qinghai-Tibet block, Chaidamo-Bayarhar/Three River block, Ta-rim block and the Indian subcontinent. The average lithospheric velocity is lowest beneath the Qinhai-Tibet region and the highest beneath the Tarim block. (2) At the depth exceeding 70 km, the Moho discontinuity in north of Yarlung Zangbo river reaches the deepest point of a "basin" configuration, whose marginal depth is about 50 km. (3) The Tibetan crustal s’ruc-ture resembles a vertically stretched out model of the Indian subcontinent. (4) Pangong Lake Fault and Nujiang Jinsha River Fault are deep-rooted structural features along which the Moho discontinuity suffers a vertical offset, with ihe northeastern side being relatively shallower. (5) The velocity structure within the Chaidamo-Bayarhar/Three River block is laterally in-homogeneous. Ranging from 90 to 110 km, the upper mantle low velocity layer in this region is more prominent as well as shallower than that beneath the Qinhai-Tibet plateau- And (6) the velocity increases monotonically with depth beneath the stable Tarim Basin block where the crust is about 50 km thick.更多还原