新疆巴楚和塔什库尔干地震台下方地壳结构研究

摘要

Using H-K receive function to search lower crust below Bachu and Taxkorgan station with high quality teleseismic records. The results show; there is a corresponding relationship between regional crustal thickness and terrain but crustal thickness in two stations are quite different; the VP/VS value in two stations are higher than normal; crustal thickness and wave velocity ratio in Bachu are forty four kilometers and 1. 849 while there is an obvious fault at depth of twenty one kilometers with low ratio and is corresponding with lower interface of focal depth in Jiashi region, it might be the brittle-ductile transfer zone;crustal thickness and wave velocity ratio in Taxkorga are sixty nine kilometers and 1.847 which indicated plastic flow easily happened and promoted condition for transformation.%利用位于新疆塔里木盆地的巴楚地震台(BCH)和西昆仑山区的塔什库尔干地震台(TAG)多年记录的高质量远震波形数据,应用接收函数H-κ叠加方法研究了台站下方的地壳结构.研究结果显示,BCH和TAG地震台下方地壳厚度差异分明,区域地壳厚度与地形有很好的对应关系；两个台都具有高的地壳平均波速比VP/VS值.BCH台下方的地壳厚度为44 km、地壳内的平均波速比为1.849,在该台地壳中部21 km处存在清晰的间断面,该间断面内存在低的平均P波波速和VP/VS值,该间断面的深度与邻近巴楚台的伽师震源区的精确定位的震源深度下界面一致,可能为地壳内的脆-韧转换带.TAG台下方的地壳厚度为69 km,地壳内的平均波速比为1.847,较厚的地壳和高波速比可能表明该台下地壳的物质易于发生塑性流动,为地壳的变形和增厚创造了条件.