蒙古及邻区重磁异常的小波多尺度分析特征

Wavelet multiscale analysis of gravity and magnetic anomalies in Mongolia and adjacent regions

蒙古位于中亚造山带中部,是认识中亚造山带构造演化的关键区域.基于SGG-UGM-1重力场模型和EMAG2磁场模型,分析蒙古及周边地区的重力异常和磁异常的空间展布特征.文章对重磁异常场进行二维小波多尺度分析,并利用功率谱分析方法得出小波逼近和细节信号的等效源深度.结果显示:蒙古及邻区的重磁异常特征与该区的地质构造吻合,反映了蒙古弧形构造特征;重磁异常的小波多尺度分析结果揭示了断裂带异常可能是由于壳幔深部物质沿断裂隙上涌导致的密度和磁性的变化引起的.

Mongolia is located in the central part of the central Asian orogenic belt. Based on SGG-UGM-1 gravity field model and EMAG2 magnetic field model, the spatial distribution characteristics of gravity anomalies and magnetic anomalies in Mongolia and surrounding areas are analyzed. The two-dimensional wavelet multiscale analysis of gravity and magnetic anomaly field is carried out, and the equivalent source depth of wavelet approximation and detail signal is obtained by using the method of power spectrum analysis. The results show that the gravity and magnetic anomalies in Mongolia and adjacent areas are consistent with their geological structures,which reflects the arc-shaped structural characteristics of Mongolia. Besides, the wavelet decomposition results of gravity and magnetic anomalies reveal that the fault zone anomalies are probably caused by the change of the intensity and magnetic of the deep material of crust and mantle when the material wells up along the fractures.