青藏高原布格重力异常匹配滤波分析及其构造意义

The matched-filter analysis of Bouguer gravity anomaly in Qinghai-Tibet Plateau and its tectonic implications

利用匹配滤波的方法处理了青藏高原布格重力异常数据。基于重力异常一阶垂直导数的径向平均对数能谱曲线,青藏高原布格重力异常场可分为三层异常场。其中龙木错—双湖构造带在中部重力异常场和深部重力异常场图中都有显现;革吉—改则—错勤—申扎隐伏断裂在浅部和中部重力异常场中都存在。另一个明显的特征是藏北都显示有巨大且平缓的低重力异常圈闭,这与藏北Pn波速较低和Sn波缺失的特征吻合;在藏南存在一系列近东西向展布的重力异常断块。

Bouguer gravity anomaly data from Qinghai-Tibet plateau were processed by the match-filter method.According to he first order vertical derivative radial average logarithmic energy spectrum curves,the Bouguer gravity anomaly in Qinghai-Tibet Plateau can be divided into three layers.The Longmuco-Shuanghu tectonic zone is always discerned in the middle and deep gravity anomaly field,whereas the Geji-Gaze-Cuoqen-Shenza concealed fault is always existent in the shallow and middle gravity anomaly field.There is a huge and smooth low gravity anomaly contour line encirclement in Qiangtang terrane of northern Tibet,and there exist a series of WE-trending gravity anomaly blocks in southern Tibet.