基于重磁反演的三维岩性填图试验——以安徽庐枞矿集区为例

3D lithologic mapping test based on 3D inversion of gravity and magnetic data: A case study in Lu-Zong ore concentration district,Anhui Province

开展大型矿集区深部精细结构探测研究,通过岩性识别与填图实现矿集区5km以内"透明化",发现深部矿产、揭示成矿规律是实现资源可持续发展的主要途径。鉴于重力和磁力数据覆盖面积广、采样密度高,重磁三维反演算法比较成熟,采用重磁反演进行岩性填图是现阶段实现三维岩性填图最有可能的途径。本文以安徽庐枞矿集区为例,提出了基于重力、磁力三维反演的岩性填图流程并开展了填图试验。在分析岩性和密度、磁化率关系的基础上,采用高精度的重力和航磁数据,进行先验信息约束的重磁三维反演,对反演所得的密度体和磁化率体进行逻辑拓扑运算,获得了庐枞矿集区地下5km以内五类主要岩性的三维分布。岩性填图结果显示的浅部特征与地表地质填图结果基本吻合,更重要的是反映了深部岩性的变化,弥补了地表地质填图的不足。庐枞矿集区岩性填图试验结果表明,开展基于重磁三维反演的岩性填图,是了解矿集区深部岩性特征,发现深部矿产的有效方法。

Through lithologic mapping to achieve ore concentration district transparent within 5kin depth is the main way to realize deep fine structures study, to explore deep mineral resources and to reveal metallogenic regularity of large-scale ore district. Owing to the wide covered area, high sampling density and mature three-dimensional inversion algorithm of gravity and magnetic data, so gravity and magnetic inversion become the most likely way to achieve three-dimensional lithologic mapping at the present stage. In this paper, we take Lu-Zong （Lujiang County to Zongyang County in Anhui Province, East China） ore concentration district as an example, we proposed lithologic mapping flow based on 3D inversion of gravity magnetic and then carry out the lithologic mapping test. Based on the analysis of relations between lithology and density and magnetic susceptibility, 3D inversion with prior information of high-precision gravity and aeromagnetic data were carried out. Then, we use logical topology operations between density 3D model and susceptibility 3D model obtained three-dimensional distribution of five main type lithologies in the Lu-Zong ore concentration district within 5km depth. The result of lithologic mapping not only showed that the shallow characteristics and surface geological mapping are basically coincide, more importantly reveals the deeper lithologic changes, it make up the insufficient of surface geological mapping. The lithologic mapping test results in Lu-Zong ore concentration district showed that lithological mapping using 3D inversion of gravity and magnetic is a effective method to reveal the lithological characteristics and to explore deep mineral resources in ore concentration district.