Mineral Prediction Of The Xidamingshan Silver Polymetailic Ore District,Guangxi

Xidamingshan district is one of the most important Ag-Pb-Zn polymetallicmetallogenic regions in Guangxi, and Fenghuangshan Ag-Pb-Zn and Lujing Pb-Zndeposits are two representative deposits distributed in this district. Field investigationand microscopic observation combined with ore deposit geochemical analysis havebeen carried out on these two deposits, and an ore-forming metallogenic model hasbeen constructed, with a focus on the research of genesis and ore-forming regularityof the polymetallic deposits in the district. Geological multi-information of thisdistrict has been extracted and synthetical mathematical prospecting models havebeen constructed, using new techniques and methods of GIS. Based on these, hiddenpolymetallic deposits of this district have been predicted, and further prospectingtargets have been delineated.The following are the achievements obtained in this dissertation.1. Field investigation and microscopic observation support division ofmetallogenic process of the Fenghuangshan and Lujing deposits into hydrothermaland supergene metallogenic epochs, the former of which is the main metallogenicepoch.2. The δ34SV-CDTvalues of the sulfide minerals from the two deposits are close to0, and the hydrogene and oxygen isotope values of ore-forming fluids are in the rangeof normal magmatic water. These isotopic data are consistent with derivation of sulfurand fluid for the formation of the deposits mainly from magma in the depth.3. The geological, aeromagnetic, ETM+and geochemical data of this districthave been dealt with using GIS techniques and mathematical modeling methods, withextracting prospect information on the strata, the faults, the folds and the geochemicalanomalies. A multivariate geological database of this district has been constructed forprospecting.4. Level analysis, weight of evidence and fuzzy logic methods have been adoptedfor mathematical modeling, and prospect targets of this district have been delineated using GIS and fractal methods. Through the comparison of the three different kinds oftargets combined with the research of distribution data of the deposits (or occurrences)in this district, these prospect targets have been classified based on their levels. Theresults can provide scientific basis for further prospecting.