小波多尺度分析在青藏高原东缘重力场的应用

Application of wavelet multi-scale analysis in the gravity field on the eastern edge of the Qinghai-Tibet plateau

在印度板块与欧亚板块的碰撞作用下,青藏高原的深部塑性物质在碰撞挤压作用下向外挤出,青藏高原东缘发育多条东西向伸展南北走向断裂构造带,构造背景复杂,地震活动频繁。基于WGM2012地球重力场模型,采用小波多尺度分析对青藏高原东缘卫星重力数据进行处理,利用径向平均功率谱计算分析多尺度小波分解后的重力异常的物源平均深度,结合前人测深地震资料反演的地壳厚度与地质背景利用分解的5阶小波逼近重力异常,对研究区域莫霍面进行界面反演,并对东西走向的剖面进行二度半模型密度参数拟合反演,研究区域莫霍面起伏反演结果与前人研究成果较一致,呈现由西北至东南逐渐变浅的趋势,间接表明青藏高原深部物质向东逃逸。

Due to the collision between the Indian plate and the Eurasian plate,the deep plastic material of the Qinghai-Tibet Plateau extruded out of the plateau under the effect of collision and compression.The eastern margin of the Qinghai-Tibet Plateau developed many east-west extending north-south fault structural belts with a complex tectonic background,with high activity of Earthquake.Based on the WGM2012 Earth Gravity Field Model,Wavelet multi-scale analysis was used to process satellite gravity data on the eastern edge of the Qinghai-Tibet Plateau,and then radial average power spectrum was applied to calculate and analyze the average source depth of gravity anomalies after multi-scale wavelet decomposition.Based on the previous research results and geological background the decomposed 5th-order wavelet was used to approximate the gravity anomaly to perform interface inversion of the Moho surface in the study area.We also performed two-degree half-model density parameter fitting inversion on the east-west section and the Moho surface undulation inversion in the study area.The results of the evolution are more consistent with previous research results,showing a trend of gradually becoming shallower from northwest to southeast.This indirectly indicates that the deep material of the Qinghai-Tibet Plateau escapes eastward.