Geological Characteristics And Metallogenic Prediction Of Huashandong Tungsten Deposit In Xiushui County,Jiangxi Province

The Huashandong tungsten deposit in Xiushui County,Jiangxi Province,is tectonically located in the Jiuling uplift of the Lower Yangtze Block,and lies in the middle segment of the Jiuling mineralization belt of the central Jiangnan tungsten-tin-copper-gold metallogenic zone.This deposit is situated about 60 km east to the Dahutang ore concentration area.In the mining district,there shows intensive geochemical anomalies,and develops complex structures and the concealed Jinning granodiorite pluton,thus has superior metallogenetic conditions.With the on-going of exploration work,a thick tungsten ore body characterized by "one area with four mineralization type" was found near the cryptoexplosive breccia pipe in this district.The Huashandong deposit has become one of the deposits with great potential discovered in recent years,and it is prospective that the mineral reserve could be in large scale.Based on a fully collection of the previous data and a synthesis of the regional geological background,tectonics,geophysical-geochemical anomalies and characteristics of the plutons,this thesis has conducted a detailed study including mineralogy,petrology,economic geology and geochemistry through field geological survey and synthetical analysis.Thereby,this paper has comprehensively revealed the characteristics of strata,structure,igneous rocks and alteration-mineralization in the mining district,and systematically analyzed the data of soil geochemical anomalies and controllable source audio frequency magnetotelluric sounding,and finally summarized its mineral deposit features.It is proposed that the Huashadong tungsten deposit was formed via a hydrothermal process including alteration-cryptoexplosion-filling based on the intrusion of granitic magmas.The low grade metamorphic rocks of the Shuangqiaoshan Group,which are widely exposed in the area,has provided abundant ore-forming elements.The intersection and compound sites of different direction faults are key positions controlling mineralization.The cryptoexplosive breccia pipe especially provides an important ore hosting space.There are multiple mineralization types in the mining district,including granodiorite type,greisen type,cryptoexplosion breccia type and dense quartz vein type,which are coexisted or intertwined around the concealed pluton,thus forming a compound tungsten polymetallic deposit.Using isotopic dating techniques,this paper has obtained a zircon LA-ICP-MS U-Pb age of 863±18Ma(MSWD=0.024)for the granodiorite which are closely associated with mineralization,and a Re-Os age of 805±5Ma(MSWD=1.01)for molybdenite in the ores.These results indicate that the ore-forming age is slightly later than that of the granodiorite.The mineralization was closely related with the differentiation of the granodioritic magmas.The Huashandong tungsten deposit is the product of magmatic activities during Jinning period.By investigating the genetic mechanism,this paper has finally established a metallogenic model for this deposit.In combination with a comprehensively analysis of the available mineral deposit features and ore prospecting results,the prospecting potential of tungsten ore in Huashandong,Xiushui area has been predicted by using prospecting-information contents method.This work has finally identified four prospecting areas including two A-level and two B-level subareas,thus has important implications in directing the follow-up exploration in this area.