应用磁视散度及磁源重力异常确定低磁纬度地区磁性体分布-以哥伦比亚普图马约盆地为例  

Determining the distribution of magnetic bodies at low magnetic latitude area by using magnetic apparent divergence and pseudo-gravity anomalies-follow the example of Colombia Putumayo basin

作　　者：马杰[1] 袁炳强[1] 张春灌[1] 韩利[1] 赵晴[1] 

机构地区：[1]西安石油大学地球科学与工程学院,西安710065

出　　处：《地球物理学进展》2013年第3期1365-1374,共10页Progress in Geophysics

基　　金：西安石油大学研究生科研创新基金(2011cx00832)资助

摘　　要：低磁纬度地区受斜磁化的影响,用常规方法很难准确确定磁性体的平面分布特征.为了研究位于低磁纬度地区普图马约盆地的磁性体分布特征,本文根据场的散度原理,假定磁ΔT异常为具有一定方向的矢量场,其方向与磁化方向一致,导出了磁ΔT异常视散度的计算方法;根据磁位与引力位的关系,在频率域中通过磁ΔT异常求取了磁源重力异常,并尝试利用拉普拉斯方程计算磁源重力异常垂向二阶导数.本文设计理论模型讨论了磁ΔT异常视散度、磁源重力异常垂向二阶导数的特征与磁性体平面分布特征的关系,证明了上述方法的有效性.进而利用上述方法推测了普图马约盆地磁性体的平面分布特征,结果表明:应用磁视散度及磁源重力异常确定的普图马约盆地磁性体分布与实际地质特征吻合较好,取得的成果对普图马约盆地相关地质研究及对低磁纬度地区的磁性体的确定有一定的参考意义.Because the low magnetic latitude area is influenced by oblique magnetization, it is difficult to accurately determine the characteristics of the plane distribution of the magnetic bodies with the conventional method. In order to study the magnetic bodies distribution characteristics of the Putumayo basin at the low magnetic latitudes, the article assumes the magnetic AT anomaly is a vector field with a certain direction according to the principle of the field divergence, and the direction is the same as the magnetization direction. The computing formula of the apparent divergence of the magnetic AT anomalies is deduced form the principle of the field divergence. According to the relationship between magnetic potential and gravitational potential, the paper calculates the pseudo-gravity anomalies through the magnetic AT anomalies in the frequency domain, and tries to calculate two second vertical derivative of the pseudo-gravity anomalies by Laplace equation. The method above has been proved efficient since the article has discussed the relationship among the apparent divergence of the magnetic AT anomalies, the two second vertical derivative of the pseudo-gravity anomalies and the characteristics of the plane distribution of the magnetic bodies.

关 键 词：低磁纬度地区 磁异常 散度 磁源重力异常 磁性体 

分 类 号：P318[天文地球—固体地球物理学]