新疆及其毗邻地区地震层析成像

SEISMIC TOMOGRAPHY OF XINJIANG AND ADJACENT REGION

利用新疆地震台网及其毗邻地区的国外地震台站提供的地震Ｐ波到时数据，重建了新疆及其毗邻地区地壳上地幔的三维速度图像．主要结果是：１．研究区地壳上地幔的地震波速度存在明显的横向不均匀性．这种不均匀性出现在不同构造单元之间，也出现在各构造单元之内．２．一般来说，研究区域内盆地是上地幔的隆起区，褶皱系是上地幔的坳陷区．３．岩石层厚度和软流层的深度与全球的平均结果有较大不同．４．海洋岩石层或大陆岩石层板块在兴都库什和克什米尔与中国交界地区的消减明显存在．５．地壳上地幔物质运动比较剧烈，有部分熔融物质上涌到地壳中部或更浅的深度．

In this paper,the three-dimensional velocity images beneath the Xinjiang and adjacent region are reconstructed using P-wave arrival time residuals of regional earthquakes recorded by Xinjiang seismic station network and some outland seismic stations near Xinjiang.Studies indicate:(1)There are distinct lateral heterogeneities of the crust and upper mantle beneath the Xinjlang and adjacent region. This local heterogeneity not only exists between different tectonic units,but also exists in every tectonic units.(2)In general,the upper mantle uprises beneath basins,and it depresses under fold systems. (3) It is noticed that the lithosphere thickness and asthenosphere depth is fairly different from global average result. (4) There is clear evidence of subduetion of oceanic and continental lithosphere plate in the border region between the Hindukush,Kashmir region and China.(5) Matter movement in the crust and upper mantle seems quite strong, part of the melied matter has moved up to the middle crust or evenshallower.