摘要
根据高阶地磁场模型NGDC-720-V3,研究塔里木盆地地壳磁异常的展布规律,磁异常的二维小波分解特点,讨论磁异常与地质构造的联系。结果显示:塔里木盆地磁异常较强,西昆仑山、阿尔金山和南天山磁异常较弱。盆地南部磁异常的空间分布与该区岩石圈区域构造基本吻合,反映出典型的山脉夹盆地的地形特征。磁异常的不同高度分布和小波分析显示,盆地磁性地壳结构分为上中下3层。盆地下磁性壳层为正磁性基底,具有全盘性。中磁性壳层的北部为负磁性基底,南部为正磁性基底,并在局部区域镶嵌负磁性物质。上磁性壳层分布小的不均匀的磁性体。
Based on the high-order geomagnetic field model NGDC-720-V3,we studied the distribution of crustal magnetic anomaly,the characteristics of the magnetic anomaly through two-dimensional wavelet decomposition,and discussed the relationship between the magnetic anomaly and geological structure in Tarim Basin. It is found that magnetic anomalies in Tarim Basin are relatively strong whereas those in west Kunlun Mountains,Altun Mountains and south Tianshan Mountains are relatively weak. The spatial distribution of the magnetic anomalies in south Tarim Basin mainly agrees with the regional tectonic structure of lithosphere,reflecting the topographic features of basin being sandwiched between mountain ranges. The distribution of the magnetic anomalies with different altitudes and the wavelet analysis show that the crustal magnetic structure in the basin may be divided into three layers,i. e.,the upper,middle,and lower layers. The lower magnetic crust is a basin-wide positive magnetic basement; the northern part of the middle magnetic crust is negative magnetic basement,while the southern part is positive magnetic basement,with negative magnetic substance inlaid in local area. In the upper magnetic crust,there are some small unevenly-distributed magnetic substances.