摘要
塔里木陆块西北缘萨热克砂岩型铜矿床构造演化、流体演化与成矿之间具有密切关系,处于一个统一系统中。矿床成岩期方解石中包裹体水的δD值为-65.3‰~-99.2‰,改造成矿期石英包裹体水的δD值为-77.7‰~-96.3‰,成岩成矿期成矿流体δ~(18)OH_2O变化范围为-3.22‰~1.84‰,改造成矿期成矿流体δ~(18)OH_2O变化范围为-4.26‰~5.14‰,指示萨热克铜矿成岩期、改造期成矿流体主要为中生代大气降水及其经水岩作用而成的盆地卤水。矿石中辉铜矿δ~(34)S值为-24.7‰~-15.4‰,指示硫主要源自硫酸盐细菌与有机质还原,部分源于有机硫。构造与成矿流体演化对砂岩铜矿成矿起关键制约作用。盆地发展早期强烈的抬升运动使盆地周缘基底与古生界剥蚀,为富铜矿源层的形成提供了丰富物源,至晚侏罗世盆地发展晚期,长期演化积聚的巨量含矿流体在库孜贡苏组砾岩胶结物及裂隙中富集,在萨热克巴依盆地内形成具有经济意义的砂岩型铜矿床。
There exist close relationships between tectonics, fluid evolution and formation of copper ore in the Sareke sandstone deposit in northwestern Tarim block, which constitute an integrated system. The δD values of inclusion water in the calcite of diagenetic stage are in the range of-65.3‰~-99.2‰,and the δD values of inclusion water in the quartz of metallogenic epoch are in therange of -65.3‰~-99.2‰,the δ~(18)OH_2O values of the ore-forming fluid in the diagenetic stage are in the range of -3.22‰~1.84‰,and the δ~(18)OH_2O values of the ore-forming fluid in the metallogenic epoch are in the range of -4.26‰~5.14‰, suggesting that the ore-forming fluid in the diagenetic stage and transformation period of the Sareke copper deposit mainly originated from the atmospheric water in the Mesozoic period and basin brine evolved from the water-rock interaction of the rainfall. The δ~(34)S values of the chalcocite in the ore are in the range of -15.4‰~-24.7‰, suggesting that most of the sulfur originated from the bacteria and reduced organic carbon in the strata, with the addition of minor organic sulfur. The evolution of the tectonics and ore-forming fluid controlled the formation of sandstone copper deposits. In the early period of the basin development, the strong uplift movement caused the erosion of the basement and Paleozoic strata in the periphery of Sareke basin,which offered abundant provenance to the formation of copper-rich source layer. Toward the late period, i.e., Late Jurassic epoch, large amounts of ore-forming fluid after long-term evolution was concentrated in the agglutinate and fissures of conglomerate in Kuzigongsu Formation, forming sandstone copper deposits with economic value in Sareke basin.
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