Metallogenic Prediction Of Endogenetic Polymetallic Deposits In Xidamingshan Area Of Guangxi Based On Evidence Weighted Evaluation Method

The West Damingshan Mountains of Guangxi is tectonically located in the junction between the Yangtze and Cathaysia blocks in South China.The region has gone through significant tectonic and magmatic activities and successively experienced plate subduction and closure of the Paleo-Tethys Ocean,convection and emplacement of the Emeishan super mantle plume,and subduction of the Pacific plate.The favorable mineralization conditions make the region an important source of lead,zinc,silver,tungsten,and bismuth in Guangxi.However,there have been lack of discovery of new mineral deposits in the region in recent years.This study integrates geological,geophysical,geochemical,and remote sensing data and uses the weight of evidence approach to carry out mineral prospecting predictions in the region.The results would provide direction for future regional mineral prospecting and exploration.It has been found in this study that the endogenous metal deposits in the West Damingshan region can be divided into two types:the medium-high temperature skarn-hydrothermal vein-like composite deposits closely related to magmatic activity and the medium-low temperature vein-like lead-zinc-silver deposits controlled by faults.The metallogenical mechanism is the water-rock reaction of magmatic hydrothermal fluids with country rocks for the first type,and the mixing of hydrothermal fluids with meteorological water for the second type.Concealed granite bodies provide mineralization and hydrothermal fluids for both of them.Metallogenesis is closely related to the Cambrian strata and fault structures.The ore-bearing strata of typical regional deposits are basically Cambrian,especially where the Cambrian and Devonian contact areas have more significant mineralization effects;while the medium-low temperature vein-like lead-zinc-silver deposits are mainly affected by NE and EW-oriented faults.The ore bodies are mostly distributed along the faults in a vein shape.The ore-forming materials are deposited in the low and gentle parts of the faults.The deposits are well developed at the intersection of the faults.The distribution of mineral deposits has an obvious positive correlation with gravity,magnetic,and geochemical anomalies and the anomalies identified from remote sensing.The most favorable metallogenic locations are where there exist low secondary gravity anomalies and high aeromagnetic anomalies,and where there are superimposed zones between iron-stained hydroxyl group and geochemical exploration anomalies.Based on the integrated geological,geophysical,geochemical,and remote sensing data,a comprehensive prospecting model for the West Damingshan region has been developed.By applying the weight of evidence approach for prospecting predictions and in terms of degree of mineralization,the region is identified and classified into four levels of mineralization:the most likely(>0.63),likely(0.63?0.31),possible(0.31?0.08),and least likely(<0.08).A total of 5 prospecting prediction target zones are determined,including two level ? and three level ? targets.The total area of the targets is 42.14 km~2.