Characteristics Of Mineralogy And Metallogenesis Of The Xiabao Ag-Pb-Zn Deposit, Jiangxi Province

The Xiabao large-scale Ag-Pb-Zn deposit is located in the southwest ofLengshuikeng ore field, Jiangxi Province. The major mineralization process can bedivided into three stages: sphalerite-pyrite polymetallic stage （stage I）;galena-sphalerite-silver minerals polymetallic stage （stage II）; pyrite-quartz （silverminerals） stage （stage III）.The EPMA indicates that element Ag presented in the ores occurs mainly asindependent silver minerals, and rare Ag in sulfides. The dominant silver minerals areakanthite and native silver, which occur in the crevasse of ferromanganese-carbonateas crevasse silver or in the clearance of ferromanganese-carbonate and early sulfidesas intergranular silver. In addition, there are also some micro canfieldites, Ag-bearingtetrahedrite, proustite, küstelite, aerosite, and eugenite, which occur in the clearanceof ferromanganese-carbonate as submicroscopic structure or in galena, sphalerite orother sulfides as unmixing of solid solution structure.The sphalerite in Xiabao deposit is a type of iron-rich sphalerite which has ahigh content of Fe. It has a higher content of Cd、In、Se、Ag、Sn、Sb while containsless content of Ga、Te、Co、Ni、Ge. These trace elements are more likely exist bymeans of Isomorphism with replacing the Zn、Fe or S in sphalerite. Ag、Sn、Sb andother elements hosted in sphalerite between the grains in forms of microscopic-submicroscopic inclusion minerals. The characteristics of low ratio in Zn/Cd、the richof Fe、Cd、In and poor in Ga indicate that the Xiabao deposit is a Subvolcanic-relatedshallow epithermal deposits.It contains less fluid inclusions in Quartz and，mainly occur liquid phaseaqueous inclusions, less rich in gas phase and single-phase aqueous inclusions，rarelyCO₂-rich and intron crystal inclusions. The average homogenization temperature offluid inclusion in stage I is335℃, and with average salinity of4.55wt%. The stage IIfluid inclusions homogenization temperatures is average of208℃, salinity is averageof5.07wt%. The stage III fluid inclusion homogenization temperature is average of175℃, salinity is average of6.35wt%. The Ore-forming fluid of Xiabao deposit have the characteristics of low temperature, low salinity, high-density.Xiabao deposit has a large range of δDV-SMOW（-83.5‰^--48.7‰），indicating thatearly ore-forming fluids mainly be magmatic fluids, with a small amount ofmetamorphic fluids mixed. δ18OH2Ovaries from5.37‰to-5.07‰reflecting a largenumber of atmospheric water joined in the late fluid. δ¹³CV-PDBvaries from-7.42‰to-2.76‰reflecting some strata mineral material joined in the fluid. δ³⁴S variesfrom0.4‰to5.5‰，average of2.94‰，presented the characteristics of mantle sourceof surful, most likely derived from the volcanic of this region. Mineralization iscontrolled by faults，decompression boiling in the fracture junction and water-rockexchange reactions of fluid together lead to the formation of deposits. Theore-forming fluids are low temperature, low salinity fluids which closely related to thesubvolcanic. It is a typical epithermal Ag-Pb-Zn deposits.