Gongwen Wang

Mineral potential targeting and resource assessment based on 3D geological modeling in Luanchuan region, China

In this paper, we used 3D modeling and nonlinear methods (fractal, multifractal, and probabilistic neural networks (PNN)) for regional mineral potential mapping and quantitative assessment for porphyry and skarn-type Mo deposits and hydrothermal vein-type Pb-Zn-Ag deposits in the Luanchuan region, China. A 3D geological model was constructed from various geological maps, cross sections, boreholes, and gravity and magnetic data. Geological features associated with mineralization were extracted using the 3D geological model and metallogenic models of porphyry and skarn-type Mo and Pb-Zn-Ag deposits. The multifractal method, principal component analysis, and power spectrum-area method were used to separate regional variability from local variability in the geochemical data. A 2.5D forward modeling of gravity and magnetic data was carried out to define the geometry, depth, and physical properties of geological bodies at depth. 3D visualization of the results assisted in understanding the spatial relations between the deposits and the other geological bodies (e.g., igneous intrusions). The PNN method was applied to represent and integrate multiple anomalies for mineral potential modeling. The concentration-area fractal method was used to classify the PNN mineral potential model. Three levels (ground surface and two subsurface horizontal planes) of mineral potential models were evaluated for undiscovered Mo and Pb-Zn-Ag deposits. Validation of the results shows that 3D modeling was useful for not only accurately extracting geological features but also for predicting potential mineral targets and evaluating mineral resources. The mineral potential targets identified consist of eight Mo potential targets and 15 Pb-Zn-Ag potential targets. Based on grade-tonnage data from the known Mo and Pb-Zn-Ag deposits and the results of 3D modeling, estimated potential resources of each of these types of deposits are 10.8 and 153.1Mt (Pb+Zn is 152.9Mt and Ag is 0.92Mt), respectively.

GeoCube: a 3D mineral resources quantitative prediction and assessment system

This paper introduces a software system (GeoCube) for three dimensional (3D) extraction and integration of exploration criteria from spatial data. The software system contains four key modules: (1) Import and Export, supporting many formats from commercial 3D geological modeling software and offering various export options; (2) pre-process, containing basic statistics and fractal/multi-fractal methods (concentration–volume (C–V) fractal method) for extraction of exploration criteria from spatial data (i.e., separation of geological, geochemical and geophysical anomalies from background values in 3D space); (3) assessment, supporting five data-driven integration methods (viz., information entropy, logistic regression, ordinary weights of evidence, weighted weights of evidence, boost weights of evidence) for integration of exploration criteria; and (4) post-process, for classifying integration outcomes into several levels based on mineralization potentiality. The Nanihu Mo (W) camp (5.0 km×4.0 km×2.7 km) of the Luanchuan region was used as a case study. The results show that GeoCube can enhance the use of 3D geological modeling to store, retrieve, process, display, analyze and integrate exploration criteria. Furthermore, it was found that the ordinary weights of evidence, boost weights of evidence and logistic regression methods showed superior performance as integration tools for exploration targeting in this case study.

Geochemistry and zircon U–Pb geochronology of the Pulang complex, Yunnan province, China

The Pulang complex is located tectonically at the southern margin of the Yidun–Zhongdian island arc belt in Yunnan province, China, and is closely related to formation of the Pulang copper deposit, which is the largest copper deposit in Asia. The Pulang complex can be divided into three intrusion stages based on contact relationships and petrological characteristics: (1) a first stage of quartz dioritic porphyry; (2) a second stage of quartz monzonitic porphyry; and (3) a third stage of granodioritic porphyry. The crystallization ages of these intrusion stages were determined by single-zircon U–Pb dating, yielding ages of 221.0 ± 1.0, 211.8 ± 0.5, and 206.3 ± 0.7 Ma for the first, second, and third stages, respectively. These dates, integrated with previous geochronological data and field investigations, indicate that the second-stage quartz monzonitic porphyry has a close spatial and temporal relationship with the large Pulang porphyry copper deposit. These age data, geochemical and Sr–Nd isotopic results suggest that the Pulang complex formed in the Indo-Chinese epoch (257 ∼ 205 Ma) by multiphase intrusion of a mixture of mantle- and crust-derived magmas.

Application of fractal models to characterization of vertical distribution of Mo deposits in Henan Province

Characterization of the spatial distribution of elements of ore deposits have a guiding role to geological exploration and deep prospecting work. To fine describe the spatial distribution properties of metal elements in ore deposits and quantitative reveal deep concealed orebodies. In this paper, on the basis of the ore-forming mechanism and geological background and Mo values in 283 boreholes of Sandaozhuang, Nannihu and Shangfanggou molybdenum deposits, three fractal models including box counting method, power-law frequency model and R/S analysis were utilized respectively to comparative study the spatial distribution properties of Mo in boreholes of three ore deposits. The results obtained by the box counting method show that the box dimensions of mineralized boreholes are greater than that of Mo values in the non-mineralized boreholes, and the spatial distribution of Mo in three ore deposits exhibit self-similarity and complexity. The complexity of the vertical distribution of Mo values and the average values of Mo in boreholes from high to low is Sandaozhuang, Nannihu and Shangfanggou; The power-law frequency analysis reveals that the vertical distribution of Mo in 283 boreholes exhibit multifractal properties, and the fractal dimensions can be used as a parameters of quantitative description mineralization intensity and mineralization types, and provide proof to multistage mineralization and the superpose mineralization of the three ore deposits; The results of R/S analysis show that the vertical distribution of Mo in boreholes of the Sandaozhuang, southern area of the Nannihu and the Shangfanggou molybdenum deposit exist positive correlation, indicating that the homogeneous distribution of Mo and better continuity of mineralization in these zones and the deep of these zones have high probability of ore forming; the vertical distribution of Mo in boreholes of the west side of the Sandaozhuang molybdenum deposit, Northern area of the Nannihu molybdenum deposit exist negative correlation, indicating that the heterogeneous distribution of Mo and worse continuity of mineralization in these zones and the deep of these zones have low probability of ore forming.

3D-GIS Analysis for Mineral Resources Exploration in Luanchuan, China

Three-dimensional (3D) geological modeling is an important method for understanding geological structures and exploring for mineral deposits. This paper presents 3D visualization and spatial analysis methodology for molybdenum polymetallic resources exploration by integrating geological, geophysical, and geochemical data to identify high potential targets for mineralization at depth in Luanchuan district. The research results show prospective targets in Luanchuan district can be derived by three methods: ① Jurassic pluton can be applied to recognize prospective targets of skarn-Mo deposit on basis of metallogenic genesis and exploration model by 3D buffer analysis using 3D geological model of Luanchuan district, ② Geoscience data (geological, geophysical, and geochemical data) can be applied to integrate and identify all potential targets of granite porphyry-skarn deposits by non-linear mathematical modeling in 3D space, and ③ gravity and magnetic data inversion and fusion additional metallogenic knowledge can be used to identify concealed orebody at depth of large porphyry Mo deposit, and the bottom of the large Mo deposit generally has higher Mo grade and alteration belt which is associated with concealed ore-bearing Jurassic granite porphyry objects/veins. Therefore, 3D geological model of Luanchuan district using geoscience data and metallogenic genesis knowledge can be applied to delineate complex geological events including stratum, fault, structure, intrusive rocks, and alteration belt, and it can be used to identify prospective targets at depth in district-scale exploration.

District-scale VMS-type Cu-Au Deposit Targeting Using Geosciences Information: A Case Study in Kalatage Region, Xinjiang Province, China

A challenge in any exploration program is the generation and prioritization of exploration targets at various scales and targeting is particularly difficult at the district to camp scale. This paper combines metallogenic models and multiple scale geoscience data with mathematical models to identify potential concealed deposits. Kalatage, as a study area, is a famous VMS-type Cu (Zn)-Au ore district in Xinjiang, China in the past 10 years. The study area is located in the Paleozoic uplift along the southern margin of Tu-Ha basin in eastern Xinjiang. The newly discovered Hongshan, Honghai, Meiling, and Hongshi Cu-Au deposits occur in the superimposed Mesozoic volcanic basin upon the northern part of Late Paleozoic Dananhu-Tousuquan accretionary arc. On basis of VMS-type deposit model, geological setting and the multiple exploration data including 1:0000 gravity and magnetic data, 1:2000 TEM and IP measurements, 1:2000 lithogeochemical survey and 1:2000 geological mapping show the potential mineral resources are more than 300 Mt Cu and 100t Au in the study area (Figure 1).

Probabilistic neural networks and fractal method applied to mineral potential mapping in Luanchuan region, Henan Province, China

This paper presents an application of probabilistic neural networks (PNN) to integrated analysis multi-mineral anomalies caused by geological information (geology, geophysics, geochemistry, and remote sensing) and to map the 1∶25000 scale potential for Molybdenum polymetallic Pb-Zn-Ag mine targets with in Luanchuan region, Hennan Province. On the one hand, according to geological anomaly theory, the use of GIS technologies for the study area of geological anomaly information extraction, Mo ore-forming elements of the multi-fractal anomaly delineation, ETM+ remote sensing data, hydroxyl and iron staining alteration of information extraction, gravity and high magnetic anomaly deep geological body inversion; the other hand, the use of PNN method (via the probability density function (non-linear Gauss transform function) for complex non-linear classification), to carry out the study area to study geoanomaly associated with mineralization (variable) integrated analysis and metallogenic prediction. The results show that PNN method combined with fractal analysis can not only integrate the study area Pb-Zn-Ag-Mo polymetallic mines pluralistic, multi-scale and multi-types of geoanomaly associated with mineralization, but also carved out of the study area of molybdenum (tungsten), and Pb-Zn-Ag are two types of mineralization favorable target areas, and this work provides a scientific basis for the deployment of mineral exploration projects in the study area.