鄂东南大冶富家山金钨矿床地球化学、年代学特征及矿床成因OA

The southeastern Hubei ore concentration area is an important component of the Middle-Lower Yangtze Riv-er metallogenic belt.In recent years,a newly discovered fine-grained disseminated gold-tungsten orebody has been found at depth in the Fujiashan mining area,on the western flank of the Yinzu pluton within this region.It is hosted in the Ordovician-Silurian Baota Formation to Xintan Formation,representing the first such occurrence at this stratigraphic level in southeastern Hubei.However,key issues including the ore genesis,mineralization age,and gold occurrence state remain unclear.Based on detailed field investigations and microscopic observations,this study conducted systematic analyses of ore mineralogy,pyrite trace elements,and sulfur isotopic composi-tions using in-situ analytical techniques including EPMA,LA-ICP-MS,and LA-MC-ICP-MS.The results show that gold occurs as invisible gold in As-rich pyrite,with Au contents of 0.21 × 10-6～17.2× 10-6 and As contents of 147× 10-6～57176×10-6,exhibiting a positive correlation,and most Au signals plot below the lattice gold solubility curve.Pyrite δ34S values range from+0.64‰ to+9.58‰,concentrating within the magmatic sulfur range(aver-age+4.27‰).Fluid inclusion and H-O isotope data indicate that the ore-forming fluids are characterized by mod-erate-to-low temperatures(140～240℃),moderate salinity w(NaCleqv)(4％～24％),and moderate pressure(210～230 MPa),representing a mixed product of magmatic water and formation water.In-situ Rb-Sr dating of hydro-thermal sericite from the mineralization stage yielded an age of(132±12)Ma,indicating that gold mineralization occurred in the Early Cretaceous.Integrating all lines of evidence,it is concluded that the Fujiashan deposit is an intrusion-related gold-tungsten deposit closely associated with Early Cretaceous magmatic-hydrothermal activity,and its formation was likely controlled by the lithospheric thinning in the Middle-Lower Yangtze River region.This study not only provides chronological and geochemical constraints for gold exploration in new stratigraphic horizons within southeastern Hubei,but also offers important references for regional metallogenic synthesis and the optimization of deep prospecting targets.