给定观测精度下的点(线)源模型重力与磁力横向分辨能力研究

Lateral resolution of gravity and magnetic data of point(line) source models under given survey accuracy

当相邻有两个或两个以上地质体时,重力(重力异常、重力张量)和磁力(磁力异常、磁力张量)就会产生叠加,这会对横向分辨多个地质体带来较大困难,因此需要对重力和磁力横向分辨能力进行深入的研究.本文从重、磁场正演理论出发,以球体(点源模型)和无限延伸水平圆柱体(线源模型)为例研究重力异常、重力张量、化极磁力异常以及垂直磁化磁力张量的理论横向分辨能力以及在给定观测精度条件下的实际横向分辨能力.通过研究表明,重力和磁力理论横向分辨能力随深度呈线性变化;给定观测精度下的重力和磁力实际横向分辨能力与形体质量、磁矩大小及观测精度呈正相关,且实际横向分辨能力随深度呈指数衰减变化.通过重力和磁力横向分辨能力的研究将为重、磁勘探的实际应用起到指导作用.

When there are two or more neighboring geological bodies,the gravity(gravity anomaly,gravity tensor)and magnetic fields(magnetic anomaly,magnetic tensor)will be superimposed,which will make it difficult to distinguish multiple geological bodies laterally.Therefore,we need to study the lateral resolution of gravity and magnetic fields.Based on the forward theory of gravity and magnetic fields,this paper takes the sphere(point source model)and the infinitely extended horizontal cylinder(line source model)as an example to study the theoretical and actual lateral resolution of gravity anomalies,gravity tensors,reduction to the pole magnetic anomalies,and vertical magnetization magnetic tensors.The results show that the theoretical lateral resolution varies linearly with depth.The actual lateral resolution of gravity and magnetic data under given survey accuracy is positively correlated with mass,magnetic moment and survey accuracy.The actual lateral resolution decreases exponentially with depth.This study will guide the practical application of gravity and magnetic exploration.