大比例尺重力调查与成矿预测：以江西朱溪钨矿外围为例

江西塔前-赋春成矿带近年发现了世界上最大的钨矿—朱溪钨铜矿。该矿床发育在富含钨铜元素的新元古代泥砂质岩基底之上，产在燕山期花岗岩与石炭纪-二叠纪灰岩接触带，阐明其覆盖区花岗岩与石炭纪-二叠纪灰岩的三维空间分布结构，是寻找该类矿床的关键问题。塔前-赋春成矿带控矿地层、花岗岩仅有微弱磁性，但是密度差异明显，这为本区开展重力工作提供了良好的前提。本文利用最新的1:5万重力调查成果，结合航磁建立了本区构造格架，使用重磁三维反演建模技术建立本区三维地质模型，取得了以下成果：（1）对区内控矿地层进行立体识别划分，推断了塔前-朱溪、双田-大游山和临港-乐河镇石炭-二叠系条带深部延展形态，推断红梅岭-排前村和刘家滩-珍珠山深部存在两条隐伏石炭-二叠系条带；（2）发现本区岩体具有环形重力低夹局部重力高的异常特征，结合磁法区分岩浆岩岩性，圈定了本区隐伏岩体；（3）根据朱溪钨铜多金属矿物化探异常特征，圈定了两类深部成矿有利靶区：一类位于地表出露石炭纪-二叠纪灰岩沿断裂延伸与隐伏岩体接触带；一类位于推断的隐伏石炭纪-二叠纪灰岩与隐伏岩体接触带。（4）塔前-赋春成矿带重力工作较少，通过分析本次重力调查成果，发现在地形复杂、具有明显密度差异的推覆构造发育地区开展1:5万重力调查可取得较好的勘查成果。重力调查工作成本低，工作周期短，在圈定的成矿有利靶区内开展大比例尺综合物化探异常查证和矿产调查工作，能有效提高矿产勘查效率；在地形、构造复杂地区推广应用1：5万重力调查并建立三维地质模型对开展深部找矿预测具有重要意义。

Large-scale gravity survey and metallogenic prediction: An example of the Zhuxi tungsten deposit in Jiangxi Province

The Zhuxi tungsten-copper deposit, , discovered in the Taqian-Fuchun metallogenic belt, Jiangxi Province in recent years, is the largest tungsten deposit in the world. This polymetallic deposit is hosted in the Neoproterozoic argillaceous sandy rock basement rich in tungsten and copper, and occurs in a contact zone between Yanshanian granite and Carboniferous-Permian limestone. Clarifying the 3D spatial distribution of granite and Carboniferous-Permian limestone in the covered area is the key problem in searching for new deposits of this type The ore-controlling strata and granites in the Taqian-Fuchun metallogenic belt have only weak magnetism, while their density difference is obvious thus permits to use the gravity to conduct further surveys. In this work, based on the results of 1: 50 000 gravity survey, combined with aeromagnetic data, the structural framework of this area is established, and the three-dimensional geological model of this area is constructed by using gravity and magnetic three-dimensional inversion modeling. These results permit to recognize the ore-controlling strata in a three-dimensional perspective and to infer the deep extension morphology of Taqian-Zhuxi, Shuangtian-Dayushan and Lingang-Lehezhen Carboniferous-Permian belts. It is inferred that there are two concealed Carboniferous-Permian belts in the deep subsurface below the Hongmeiling-Paiqian Village and Liujiatan-Pearl Mountain. It is found that the rock mass in this area has the abnormal characteristics of annular gravity low and local gravity high. Combined with the magnetic method to distinguish magmatic lithology, a concealed rock mass in this area is delineated. According to the characteristics of geophysical and geochemical anomalies, two types of favorable targets for deep mineralization are delineated, one is located in the contact zone between the exposed Carboniferous-Permian limestone along the fault and the concealed rock mass, and the other is located in the inferred contact zone between the concealed Carboniferous-Permian limestone and the concealed rock mass. Previous gravity work of Taqian-Fuchun metallogenic belt is less. The analysis of the results of this gravity survey suggests that the 1: 50 000 gravity survey works well in the nappe structure with complex topography and obvious density difference at A low cost and over a short working period. This work demonstrates that carrying out large-scale comprehensive geophysical and geochemical anomaly verification and mineral survey in the delineated metallogenic favorable target area can effectively improve the efficiency of mineral exploration; popularizing the application of 1: 50 000 gravity survey and establishing three-dimensional geological models in areas with complex topography and structure is of great significance for prospecting prediction toward the deep subsurface.