广西西大明山隐伏岩体空间形态研究

On the spatial form of concealed rock mass in Xidamingshan area of Guangxi

根据广西西大明山地区1∶5万重力资料,并在地质资料的约束下,对广西西大明山地区隐伏岩体三维形态进行了细致的模拟推断。西大明山地区1∶5万布格重力异常图与地质图的研究表明,局部重力异常主要是由西大明山隐伏岩体引起的,2013年广西第四地质队在该地区布置的ZK31901、ZK40004两个钻孔分别发现了隐伏岩体,证实了重力推断。为了求出西大明山地区隐伏岩体的三维形态,采用重磁异常三维物性反演随机子域法方法,具体步骤为三维重磁异常自动反演→重构模型体和建立反演初始模型→三维重磁异常人机交互反演→输出结果(岩体形态、顶底埋深)。通过重磁反演,比较具体的描述岩体深部的空间展布,对于该地区成矿规律研究及深部成矿预测提供了重要的资料,从而为该地区今后开展第二空间深部地质找矿提供重要资料,具有一定的意义。

According to the gravity data at 1:50,000 scale of Xidamingshan area in Guangxi,and within the limitation of the geological data,this paper conducted a detailed simulation and inference on the three-dimensional shape of concealed rock mass in Xidamingshan area of Guangxi.It is indicated in the Bouguer gravity anomaly map at 1:50,000 scale and the geological map of Xidamingshan area that local gravity anomalies are mainly caused by concealed rock mass in Xidamingshan area.The concealed rock mass found in two boreholes(ZK 31901 and ZK 40004)drilled by Guangxi Fourth Geological Team in 2013 confirm the results inferred from the aspect of gravity.To determine the three-dimensional shape of concealed rock mass in Xidamingshan area,the method of 3-D gravity and magnetic inversion for physical properties using stochastic subspaces is applied.The method includes three steps:automatic inversion of 3-D gravity and magnetic anomalies,model reconstruction and establishment of the initial inversion model,human-computer interaction inversion of 3D gravity and magnetic anomalies,as well as output result(form of rock mass,top/bottom depth).Through the gravity and magnetic inversion and the comparison of spatial distribution of rock mass at depth,the authors provided important information for the study of metallogenic regularity of the area and the prediction of deep mineralization.This data is important to the prospecting works at the second deep part of this area in the future.