Research On The Geochemical Features And Genesis Of The Panlong Lead-Zinc Deposit In Guangxi

The Panlong lead-zinc deposit, located in the southern part of the Dayaoshan Pb-Zn-polymetallic metallogenic belt, is one of typical large-size lead-zinc deposits. The metallogenic belt tectonically belongs to the compound part of the Guizhong depression and Dayaoshan uplift. In this paper, on the basis of investigating mineral deposit geology, trace element geochemistry, isotopic geochemistry and fluid inclusion geochemistry, the following conclusions are achieved:The Panlong lead-zinc orebodies were hosted by the dolomite in the Lower Devonian Shanglun Formation. The mineral deposit is characterized by laminated and banded structure, synsedimentary breccia and interlayer folds. The mineralization was related with dolomitization, baritization and silicalization, which reveals a sedimentary origin for the mineralization. The trace element and REE geochemical characteristics indicate that the mineralization of Panlong lead-zinc deposit was probably related with hydrothermal sedimentation. The sulphur isotope analysis shows that the ore-forming materials were mainly derived from the mixing between crustal magma and Devonian sea water. The Pb isotope and Sr isotope analyses reveal that the ore-forming materials came from the strata subjected to the influence of homo-phase sea water. Fluid inclusion studies indicate that the ore-forming fluids belong to H2O-NaCl system in exhalative mineralization stage, with medium to low temperature (166-289℃), low salinity (4.01%-14.07%) and low density (0.804-0.955g/cm3).Integrating the characteristics of the mineral deposit geology and geochemistry, the Panlong lead-zinc deposit shows similarity with traditional SEDEX but extraordinary difference compared with MVT. Therefore, the stratiform Panlong lead-zinc deposit belongs to SEDEX.