重力异常垂向二阶导数在攀西裂谷特征分析中的应用  

Application of the vertical second derivative of gravity anomaly for characteristics analysis of Panxi rift

作　　者：曾琴琴[1] 王永华[1] 李富[1] 吴文贤[1] 邓珂[1] 

机构地区：[1]成都地质矿产研究所,成都610081

出　　处：《地球物理学进展》2015年第1期29-33,共5页Progress in Geophysics

基　　金：中国地质调查局地质调查工作项目(1212011120918;12120113049600和12120113051500)资助

摘　　要：重力异常是地下不同规模、形态和埋深的不均匀地质体的综合响应.通过从重力异常中提取目标地质体异常,可以探测隐伏矿床、岩体或构造.而重力异常的高阶垂向导数不仅可以通过突出浅而小的地质体异常、压制区域性深部地质因素的影响来提高局部地质因素分辨能力,还可以区分水平叠加异常,确定地质体或构造边界.但阶数越高的导数,带来的高频干扰越严重.相对于其它高阶导数而言,垂向二阶导数是一种较为成熟的位场数据处理和解释方法.本文通过对攀西地区重力异常垂向二阶导数的特征分析,推断了攀西裂谷基本结构,并将其与区内已知金属矿床及重要成矿带分布位置对比,由此发现,区内主要金属矿床和成矿带均沿裂谷带分布,且沿裂谷轴部分布最为密集.结合攀西裂谷成因机制,进一步指出,区内金属矿找矿方向主要沿与岩浆热液作用密切相关的裂谷构造发育端展布.Gravity anomalies are responses of multiple inhomogeneous geologic bodies of different scales,patterns and depths.The concealed deposits,rocks or structures can be detected by extracting geological target anomalies from the superimposed gravity anomalies.The vertical high order derivatives of gravity anomalies not only make the shallow and small geological body anomaly stand out through suppressing the regional geological factor effect,which eliminates or weaken the background field effect,to improve the resolution of local geological factors,but also can distinguish horizontal stacked anomalies to determine the boundaries of geological bodies or structures.However,the higher order derivative brings more serious high-frequency interferences.Compared with the other high order derivative terms,the vertical second derivative is a more mature method,which is widely used in potential field data processing and interpretation.When distinguish adjacent geological bodies with little differences of depth or density,the vertical second derivative of gravity anomaly makes the characteristics and contacting relationships of geological bodies more prominent compared with the vertical first derivative.In this paper,the vertical second derivative of gravity anomaly in Panxi region is used,from which,the skeleton of Panxi rift is deduced.Compared with the distributions of the known metallic deposits and important metallogenic belts,we find that,the metallic deposits and metallogenic belts are mainly distributed in the rift shafts,and the most intensive position is distributed along the rift axis.Combined with the rift formation mechanism,the metallic ore exploration directions are further pointed out,which are mainly distributed along the rift developed sides that closely related with the magmatic hydrothermal fluids.

关 键 词：重力异常 垂向二阶导数 特征分析 攀西裂谷 

分 类 号：P312[天文地球—固体地球物理学]