青藏高原北缘地壳磁异常特征与区域构造

Characteristics of the crustal magnetic anomaly and regional tectonics in the northern margin of the Qinghai-Tibet Plateau

根据地面、航空、海洋和卫星磁测资料构建的最新一代高阶地磁场模型NGDC-720-V3,计算青藏高原北缘地区地壳磁异常7要素和X、Y、Z 3分量的垂直梯度和水平梯度,分析磁异常及其梯度的空间分布规律,磁异常与该区地质构造的关系以及与该区其他地球物理场的相关性.结果显示,青藏高原北缘的地壳磁异常较弱,磁异常梯度较小,基本呈东西走向分布,并且具有北高南低的趋势,可以清晰地看出盆—山构造特征.青藏高原北部磁异常的强弱与重力异常值的大小呈反相关关系.在对磁异常与温度场的相关性的研究中发现强磁异常地区地温梯度高于弱磁异常地区的地温梯度,磁异常越强的地区地温梯度越大.在对磁异常与地震波的相关性研究中发现强磁异常地区的地壳结构有利于地震波传播,弱磁异常地区的地壳结构减缓地震波传播.

According to the ground,aviation,marine and satellite magnetic data to construct the new generation of high order model of the geomagnetic field NGDC-720-V3,calculation of the northern Tibetan Plateau crust magnetic anomalies and the7 elements of X,Y,Z 3 component of the gradient of vertical and horizontal gradient analysis gradient magnetic anomaly,and its spatial distribution,magnetic anomaly and the geological structure in this area as well as the relationship between the other geophysical field correlation.The results show,the northern margin of the Qinghai—Tibet Plateau region of the earth's crust magnetic anomalies of weak magnetic anomaly gradient is small,basic was East—West distribution,and has the north south high low trend,can clearly see that the basin-range tectonics.According to the northern Qinghai—Tibet Plateau gravity anomaly distribution,contact the crustal magnetic anomaly distribution is found and magnetic anomaly and the strength of gravity anomaly value is negative correlation.On the magnetic anomalies and temperature field correlation study found strong magnetic anomaly area geothermal gradients than weak magnetic anomalies in areas of geothermal gradient,magnetic anomaly stronger regional geothermal gradient bigger.On the magnetic anomaly and seismic wave in the correlation study found strong magnetic anomaly region of crustal structure is beneficial to seismic wave propagation,weak magnetic anomalies in areas of crustal structure and slow earthquake wave propagation.