新疆东天山卡拉塔格红石铜矿床硫同位素研究

Sulfur isotope characteristics of Hongshi Cu deposit,eastern Tianshan, NW China

卡拉塔格红石铜矿床位于新疆东天山大南湖—头苏泉岛弧带北段,矿床产于陆相火山岩—次火山岩中,受断裂构造控制而呈脉状;成矿过程包括早、中和晚阶段,分别以石英—黄铁矿脉、石英—硫化物脉以及石英—碳酸盐—石膏细脉为标志;围岩蚀变以硅化、绢云母化、碳酸盐化、青磐岩化等中低温蚀变组合为特征。矿石硫化物的δ^(34)S值变化于-1.9‰~3.6‰之间,平均为1.2‰,其中黄铁矿δ^(34)S值为-1.1‰~3.6‰(平均值1.3‰),黄铜矿δ^(34)S值为-1.9‰~1.6‰(平均值0.5‰),闪锌矿δ^(34)S值为2.0‰~3.5‰(平均值2.8‰)。从早到晚,矿石硫化物的δ^(34)S值显示逐渐降低的特点,表明成矿过程中硫源发生了变化或成矿流体系统性质有所改变,由与石英斑岩有关的矿化过渡为浅成低温热液矿化。红石矿床地质与流体特征与新疆北部浅成低温热液矿床一致,应为浅成低温热液矿床。

The Hongshi Cu deposit is hosted by volcanic rocks of the Daliugou Formation in the Kalatag area, eastern Tianshan, NW China. The ore bodies are associated with quartz vein and controlled by NS- or NWW-trending faults. The ore-forming process can be divided into the early, middle and late stages, and characterized by quartz-pyrite, quartz-sulfide and quartz-carbonate veins, respectively. The δ^(34)S values of ore minerals from the Honghsi deposit show a narrow range between-1.9‰ and 3.6‰, with average of a 1.2‰. The δ^(34)S values of pyrite, chalcopyrite and sphalerite show ranges of-1.1‰ to 3.6‰,-1.9‰ to 1.6‰ and 2.0‰to 3.5‰, with the averages of 1.3‰, 0.5‰ and 2.8‰, respectively. The early-stage pyrite has a positive δ^(34)S value of 1.3‰ that are similar to the host rocks of the volcanic rocks, suggesting that the host rocks contributed much of the sulfur to the early-stage pyrite during fluid-rock interaction. However, the δ^(34)S values of the middle-stage sulfides have a near-zero δ^(34)S values indicate a possible magmatic source similar to many magmatic-hydrothermal deposits. Thus,the Hongshi Cu deposit may be considered as an epithermal mineral system.