A 3D Geological Model Constrained by Gravity and Magnetic Inversion and its Exploration Implications for the World‐class Zhuxi Tungsten Deposit, South China

Abstract

The Zhuxi tungsten deposit in Jiangxi Province, South China, contains a total W reserve of about 2.86 Mt at an average grade of 0.54 wt% WO3, representing the largest W deposit in the world. Numerous studies on the metallogeny of the deposit have included its timing, the ore‐controlling structures and sedimentary host rocks and their implications for mineral exploration. However, the deep nappe structural style of Taqian–Fuchun metallogenic belt that hosts the W deposit, and the spatial shape and scale of deeply concealed intrusions and their sedimentary host rocks are still poorly defined, which seriously restricts the discovery of new deposits at depth and in surrounding areas of the W deposit. Modern 3D geological modeling is an important tool for the exploration of concealed orebodies, especially in brownfield environments. There are obvious density contrast and weak magnetic contrast in the ore‐controlling strata and granite at the periphery of the deposit, which lays a physical foundation for solving the 3D spatial problems of the ore‐controlling geological body in the deep part of the study area through gravity and magnetic modeling. Gravity data (1:50000) and aeromagnetic data (1:50000) from the latest geophysical surveys of 2016–2018 have been used, firstly, to carry out a potential field separation to obtain residual anomalies for gravity and magnetic interactive inversion. Then, on the basis of the analysis of the relationship between physical properties and lithology, under the constraints of surface geology and borehole data, human–computer interactive gravity and magnetic inversion for 18 cross‐sections were completed. Finally, the 3D geological model of the Zhuxi tungsten deposit and its periphery have been established through these 18 sections, and the spatial shape of the intrusions and strata with a depth of 5 km underground were obtained, initially realizing “transparency” for ore‐controlling bodies. According the analysis of the geophysical, geochemical, and geological characteristics of the Zhuxi tungsten deposit, we discern three principles for prospecting and prediction in the research area, and propose five new exploration targets in its periphery.

Three-Dimensional Geological–Geophysical Modeling and Prospecting Indications of the Ashele Ore Concentration Area in Xinjiang Based on Irregular Sections

“…This method facilitates the effective construction of basic profiles, cooperation between researchers, and incorporation of researchers' geological knowledge to improve efficiency and reliability. The high applicability of this method has been proved in much research work [8][9][10][11][12][13][14], but this method is more suitable for ore concentration areas with relatively rich geological data and good stratigraphic continuity. It is difficult to reflect the actual geological situations in ore concentration areas with sparse data and complex geological structures, particularly the actual geological situations of the deep geological structures perpendicular to the profiles and in areas with sparse data.…”

Binary structure constrained gravity inversion based on seismic first arrival travel time data

“…Gravity exploration is characterized by great depth, low cost and high efficiency, and has been widely used in the study of the internal structure of the earth's crust and the exploration of the distribution of deep minerals and oil and gas resources (Guillen and Menichetti, 1984;Li and Oldenburg, 1998;Nabighian et al, 2005;Nabighian et al, 2010;Afshar et al, 2018;Yan et al, 2020;Ming et al, 2021). Gravity anomaly information is a comprehensive reflection of all density information of the stratum from top to bottom, so much so that the vertical resolution is not high, and only by stripping away the influence of the surface and shallow layers can the information of the specified destination layer be obtained.…”

Three-Dimensional Limited-Memory BFGS Inversion of Magnetic Data Based on a Multiplicative Objective Function

“…Magnetic exploration is a kind of geophysical exploration method that uses the magnetic field changes (magnetic anomalies) caused by the magnetic differences between various rocks (ore) in the crust to find useful mineral resources and study the underground structure [1][2][3]. Magnetic prospecting is widely used to search for useful mineral resources [4][5][6]. In the late 1950s and early 1960s, the Soviet Union and the United States began ocean magnetic surveys, and continental drift theory entered a new historical stage.…”