【摘要】 马元铅锌矿床是近年在扬子陆块北缘铅锌找矿的新突破。矿床主要形成于边缘基底隆起翼部震旦系灯影组中,矿体呈层状、似层状产于角砾化白云岩层间构造带中,围岩蚀变很弱。矿石中硫化物以闪锌矿、方铅矿为主,矿物成分简单,中粗粒晶质结构,充填于白云岩角砾间。矿石中矿物流体包裹体记录的成矿流体温度为100~320℃,密度为0.850~1.068g/cm3,估算成矿流体压力为24.9~31.7MPa,相应成矿深度900~1198m。矿石中硫化物的δ34SV-CDT为12.94‰~19.4‰,且δ34S黄铁矿>δ34S闪锌矿>δ34S方铅矿;硫酸盐矿物的δ34S为32.2‰~33.48‰,H2S来自海相硫酸盐的还原。矿石硫化物206Pb/204Pb为17.62~18.02,207Pb/204Pb为15.49~15.63,208Pb/204Pb为37.57~38.35,成矿金属来源于震旦纪—寒武纪地层。矿石中热液脉石矿物的δ13CV-PDB为-3.2‰~-1.2‰,δ18OV-SMOW为19.4‰~21.4‰,成矿流体中CO2为震旦系碳酸盐岩的溶解成因。马元铅锌矿床成矿流体可能为起源于盖层沉积的中低温盆地卤水,伴随碑坝穹隆构造过程,成矿流体沿灯影组白云岩层间(滑脱或溶塌)构造从盖层沉积中心向隆起边部运动并发生热液充填成矿,在成因上为MVT铅锌矿床。更多还原

【Abstract】 Mayuan is a newly discovered Zn-Pb ore deposit on the northern margin of Yangtze landmass. The ore deposit mainly occurs in the Sinian Dengying Formation around an old basement dome. The ore body is bedded and stratoid in form and lies in a structural zone of dolomite breccias along the stratification, and the wall-rock alteration is weak. The sulfide minerals sphalerite and galena are simple and assume medium to coarse grained crystals in the ore, and fill the dolomite breccias. Studies of fluid inclusions in some gangue minerals and sphalerite show that the ore-forming fluid temperatures are 100～320℃, the ore fluid densities are 0.850～1.068 g/cm3,the fluid pressures are 24.9～31.7 MPa and the corresponding metallogenic depths are 900～1 198 m. The δ34SV-CDT of sulfides are 12.94‰ ～ 19.4‰ and δ34Spyrite>δ34Ssphalerite>δ34Sgalena, and the δ34S of barite are 32.2‰ ～ 33.48‰. The mineralization H2S resulted from marine sulfate reduction. The 206Pb/204Pb of ore sulfide are 17.62 ～ 18.02,207Pb/204Pb are 15.49 ～ 15.63,208Pb/204Pb are 37.57 ～ 38.35,and the ore metals were derived from the Sinian-Cambrian strata. δ13CV-PDB of the hydrothermal gangue mineral calcite are -3.2‰ ～ -1.2‰,δ18OV-SMOW are 19.4‰ ～ 21.4‰,and the CO2 in the ore-forming fluid was derived from the dissolution of Sinian carbonates. The ore-forming fluid was a basin brine of middle-lower temperature and might have originated from Sinian-Cambrian sediments. With the Beiba dome-structure process, the fluid migrated from the sedimentary center to the margin of the dome along the structure zone between the stratifications and, as a result, the hydrothermal space-filling mineralization occurred. The Mayuan Zn-Pb ore deposit is genetically a MVT deposit.更多还原