【摘要】 大坪金矿是云南哀牢山金矿带中最大的新生代造山型金矿之一,其矿体可分为两种类型:晚元古代闪长岩岩体中金矿和中泥盆统马鹿洞组(D2m)灰岩地层中金矿。成矿流体H-O-C-S同位素研究表明,闪长岩岩体中金矿δ18OH2O为2.39‰～7.59‰,δD为-85‰～-60‰,热液方解石的δ13C值为-4.7‰～-4.6‰,黄铁矿δ34S值为-2.8‰～7.6‰,平均3.1‰,方铅矿δ34S值为0.2‰～6.3‰,平均2.0‰,而灰岩地层中金矿的δ18OH2O值为4.36‰～6.82‰,δD为-75‰～-67‰,热液铁白云石和方解石δ13C为-7.6‰～-0.5‰,黄铁矿δ34S值为2.2‰～10.2‰,平均6.5‰,显示大坪金矿中两种主要金矿类型成矿流体的组成和来源基本一致,均主要为来自下地壳的变质流体组成,但有地幔流体加入。大坪金矿属于剪切带控制的中深中温热液型金矿,其成矿与哀牢山金矿带在喜马拉雅早期强烈的壳幔相互作用有关。来自下地壳和地幔的深源流体沿超壳剪切带上升,在地壳浅部向次级断裂构造流通,分别在闪长岩体和灰岩地层中成矿。围岩不是大坪金矿的主要控矿因素。更多还原

【Abstract】 Daping is one of the largest Cenozoic orogenic type gold deposits in Ailaoshan gold belt. Gold ores in the Daping may be divided into two types:(1) Late Proterozoic diorite hosted; (2) Maludong Formation of Middle Devonian (D2m) limestone hosted. In this study,H-O-C-S isotopic compositions of fluid inclusions,hydrothermal carbonate minerals and sulphides from the Daping auriferous quartz veins were analysed,and the results show that:In the diorite hosted gold ores,the δ18OH2O and δD are 2.39‰~7.59‰ and-85‰~-60‰,the δ13C of hydrothermal carbonate minerals are-4.7‰~-4.6‰,δ34S of pyrite and galena are-2.8‰~7.6‰ (average 3.1‰) and 0.2‰~6.3‰ (average 2.0‰),respectively,while in the Middle Devonian (D2m) limestone hosted gold ores,the δ18OH2O and δD are 4.36‰~6.82‰ and-75‰~-67‰,δ13C of hydrothermal carbonate minerals are-7.6‰~-0.5‰,δ34S of pyrite are 2.2‰~10.2‰ (average 6.5‰),respectively,suggesting that stable isotopic compositions of ore-forming fluids in the two different type gold ores are nearly the same. Both of their ore-forming fluids and materials might have derived from same source:Lower crust and upper mantle. Daping is a typical ductile shear zone controlled mesothermal gold deposit,crust-mantle interaction occurred at the early of Himalayan Orogeny might have played an important role in its mineralization. At about 33Ma ago,the middle and lower crust in the Daping area suffered high temperature and high pressure metamorphism because of ductile deformation and upwelling upper mantle magmas. The ore-forming fluids enriched in CO2,which were generated by granulitization and firing of the upwelling upper mantle magma,were transported to the middle to upper crust along the ductile shear zone,and finally precipitated auriferous sulfide-quartz veins in the brittle structures in diorite batholith or D2m limestone because of declined temperature and pressure and subsequent boiling. Lithologic characters of wall rocks is not an important controlling factors in mineralization of Daping gold mine.更多还原