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三维地质建模是实现深部矿产勘查突破的重要途径,其通过控矿地质体的三维建模,直观刻画控矿要素之间的空间、成因和演化关系,帮助理解成矿系统,开展深部找矿预测.当前三维建模主要采用地质资料构建,在缺少钻孔等已知资料的情况下,难于构建出可靠的三维地质模型.为了克服常规三维地质建模方法可信度低、精度差的缺点,本文将重磁交互反演技术引入到三维地质建模中,提出了基于先验信息约束,通过二度半剖面交互反演、三维物性反演联合修正的三维地质模型方法.采用该方法建立了铜陵矿集区的三维地质模型,并开展了深部找矿预测,取得以下主要认识:1)基于先验信息约束的重磁交互反演建模技术能大幅提高三维地质模型的可信度,是实现地下地质体“透明化”的重要途径;2)铜陵地区重要控矿地层(C-P-T2)主要分布于向斜区和火山岩覆盖区,深部岩浆岩条件优越,深部找矿工作应从传统的背斜隆起区转向向斜区和火山岩覆盖区以及部分凹陷区,这将极大拓展铜陵地区找矿空间;3)铜陵地区传统的五大矿田的侵入岩均具有复合岩体特征,特别是与辉石闪长岩共生的矿产以铁铜矿为主,而与金矿密切相关的侵入岩则多为中酸性岩体,这一推断如果成立,将对铜陵地区找矿突破产生重大影响;4)铜陵地区的推覆构造十分发育,木镇凹陷区的早古生代基底和南陵盆地北西缘的戴公山背斜就是一套区域性推覆构造的产物,三维地质模型还揭示铜陵地区侵入岩具有深、中、浅三重结构,这为铜陵隆起的推覆成因提供了证据,也指示了在铜陵之外再寻找类似铜陵矿集区的良好前景.
Three-dimensional geological modeling is an important way to realize deep mineral exploration breakthrough. Through the 3D modeling of ore-controlling geological body, it can depict the space, genesis and evolution between ore-controlling elements intuitively, help to understand the metallogenic system and carry out deep prospecting It is difficult to construct a reliable 3D geological model in the absence of known data such as drilling etc. In order to overcome the shortcomings of low confidence and poor precision of conventional 3D geological modeling methods , This paper introduces the gravity and magnetic inversion technique into the 3D geological modeling and proposes a three-dimensional geological model method based on the prior information constraint, the second-half cross-section inversion and the joint correction of the 3D physical inversion. The three-dimensional geological model of Tongling ore district is established and the deep prospecting prediction is carried out. The following major findings are obtained: 1) The gravity and magnetic inversion modeling technology based on prior information constraint can greatly improve the credibility of 3D geological model, Is an important way to realize the underground geological body “transparent ”; 2) The important ore-controlling strata (CP-T2) in Tongling area are mainly distributed in the syncline area and volcanic rock coverage area, The favorable conditions are that the deep prospecting work should be shifted from the traditional anticline uplift zone to the syncline area and the volcanic rock coverage area and part of the depression area, which will greatly expand the prospecting space in Tongling area. 3) Intrusive rocks in the traditional five major orefields in Tongling area All of them have the characteristics of composite rock mass, especially the coexisting minerals with pyroxene diorite are mainly iron and copper, while the intrusive rocks which are closely related to gold ore are mostly medium-acid rocks. If this inference is true, 4) The nappe structures in Tongling area are well developed. The Early Paleozoic basalts in the Muzhen depression and the Daigongshan anticline on the northwestern margin of the Nanling Basin are the products of a regional nappe structure. The three-dimensional geology The model also reveals that the intrusive rocks in Tongling area have deep, medium and shallow triple structures, which provides evidence for the genesis of the uplifts in Tongling uplift and also indicates a good prospect for finding similar Tongling ore district outside Tongling.