安徽冬瓜山叠生式层状铜矿热液改造型流体研究

Study on Altered Fluids of Diplogenetic Stratified Copper Hydrothermal Solution in Dongguashan, Anhui Province

研究证实冬瓜山叠生式层状铜矿热液改造型流体包裹体均一温度介于 2 2 4℃～ 478℃之间 ,盐度介于 3 2 0 %～ 43 9%之间 ,呈双峰式分布 ;硬石膏与石炭系海水硫酸盐δ34 S相当 ,矿石黄铁矿和石英闪长岩黄铁矿中δ34 S比较接近岩浆中的硫 ;表明冬瓜山叠生式层状铜矿床既有沉积特征 ,又有热液改造的特征 ,且后者在铜矿富集成矿过程中占主导地位。碳同位素研究表明 :矿区地层和矿体中方解石脉的δ1 3C、矿石中的δ1 3C和矿体石英脉中的碳主要来源于沉积碳酸盐 ,但经过一系列的地质作用 ,使得方解石脉中的δ1 3C减少的速率明显的比围岩快。石英脉的δ1 8OSMOW介于 0 937%～ 1 390 %之间 ,δDSMOW介于 - 5 50 0 %～ - 7 2 90 %之间 ,说明流体中的氧、氢同位素接近岩浆水。

The homogeneous temperature is demonstrated to be ranged from 224℃ to 478℃, 3 20～43 9 eq·wt% of salinity for the altered fluid inclusions of diplogenetic stratified copper hydrothermal solution in Dongguashan, Anhui Province, distributing in double peaking; anhydrite is correspondent to the sea water sulfate δ 34 S in Carboniferous system, δ 34 S in pyrite ore and pyrite in quartz diorite is close to the sulfur in magma which shows that the diplogenetic stratified copper deposit is both characteristic of sedimentation and hydrothermal alteration, with the latter possessing a leading position in the course of copper enrichment. The carbon isotopic study shows that the origins for δ 33 Cs in the formation of the ore district, in the calcite vein of the ore body, in the ores and the carbon in the quartz veins of the ore body are mainly from sedimentary carbonates, making δ 33 C reducing faster in speed in calcite veins than that in the country rocks through a series of geological processes. δ 18 O SMOW ranges from 9 37‰～13 90‰, δD SMOW ranges from -55 00‰ ～ -72 90‰ for the quartz veins, indicating the oxygen and hydrogen isotopes in the fluids approach magma water, so the hydrothermal altered fluids are mainly derived from magmas.