| 贾润幸,方维萱,胡雷雷,刘得磊.西南天山中元古界阿克苏群原岩恢复与铜金富集成矿规律[J].矿产勘查,2023,14(3):360-376 |
| 西南天山中元古界阿克苏群原岩恢复与铜金富集成矿规律 |
| Protolith restoration and copper-gold enrichment of Mesoproterozoic Aksu rock group in the southwestern Tianshan Mountains |
| 投稿时间：2022-02-21 |
| DOI：10.20008/j.kckc.202303004 |
| 中文关键词: 西南天山 萨热克铜矿床 长城系阿克苏群 中元古界 锆石测年 金铜矿化 |
| 英文关键词: southwest Tianshan Mountains Sareke copper deposit Aksu Group of Changcheng System Mesoproterozoic zircon dating gold and copper mineralization |
| 基金项目:本文受中国地质调查局项目“新疆乌恰县萨热克地区铜多金属矿整装勘查区矿产调查与找矿预测”(121201004000150017-47；121201004000160901-67)和“塔西砂砾岩型铜铅锌矿床成矿规律与找矿预测”(201511016)联合资助。 |
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| 中文摘要: |
| 西南天山萨热克地区沉积盆地下基底为长城系阿克苏群,岩石类型主要为石英片岩、黑云片岩、云母片岩和大理岩等,总厚度达6700 m,其中发现了多处铜金矿化点。研究表明长城系阿克苏群原岩主要以碎屑岩+碳酸盐岩为主,并含有一定的火山岩组分,岩石形成的构造背景表现为被动大陆边缘的陆源碎屑岩沉积,由于地壳的多次升降形成了多层碎屑岩+碳酸盐岩沉积,并伴有火山喷发沉积作用。从长城系阿克苏群黑云片岩锆石测年结果来看,其不一致线与谐和曲线上交点的207Pb/206Pb年龄(1609±190)Ma,推断长城系阿克苏群形成于中元古代。从长城系阿克苏群铜金矿化流体包裹体测试结果来看,热液流体主体平均温度为165.80～201.54 ℃,部分单个包裹体达到352 ℃,平均盐度(wt%NaCl)为16.87～18.40；金(铜)矿化包裹体中气相成分以CH4为主,铜(金)矿化包裹体中气相成分以CO2和N2为主,含少量的CH4。结合本区构造变形过程认为该区长城系阿克苏群的铜金矿化主要来源于该层岩石本身,构造运动使岩石发育大型褶皱断裂带和剪切破碎带,岩石中的Au、Cu等有用组分随着不断增加的温压变化而发生活化形成热液流体,富含Au、Cu等有用组分的热液流体沿构造裂隙或韧性剪切裂隙沉淀富集形成含铜石英脉或含金微细脉,热液流体在演化后期盐度(wt%NaCl)有降低趋势。本区不同岩(矿)石中硫同位素差异较大,这主要与其所处的不同形成环境有关,也与沉积盆地长期的构造演化有关。中元古界长城系阿克苏群为晚侏罗世—早白垩世沉积期重要的剥蚀物源区,为沉积型铜铅锌矿床的形成提供了一定的物质来源。 |
| 英文摘要: |
| The lower basement of the sedimentary basin in Sareke area of the southwest Tianshan Mountains is the Aksu Group of the Changcheng System. The rock types are mainly quartz schist, biotite schist, mica schist and marble, with a total thickness of 6700 m. Many coppper-gold mineralization points have been found in the Changcheng System. The protolith of Aksu Group of Changcheng System mainly consist of clastic rocks and carbonate rocks, and contain some volcanic components, which are terrigenous clastic rocks deposited in passive continental margin. Due to the ups and downs of the crust, multi-layer clastic rocks and carbonate rocks were formed, accompanied by volcanic eruption. The SHRIMP U-Pb ages for zircons from biomica schist in the Aksu Group of the Changcheng System show that the 207Pb/206Pb age at the intersection of the discordian line and the concordia curve is (1609±190)Ma, suggesting that the Aksu Group of the Changcheng System was formed in Mesoproterozoic. Fluid inclusion test results of vein quartz in the Aksu Group of the Changcheng System show that the average temperature of the hydrothermal fluid range from 165.80 ℃ to 201.54 ℃, some individual inclusions reach 352 ℃, and the average salinity (wt% NaCl) range from 16.87 to 18.40. The gas components of the gold (copper) mineralized inclusions are mainly CH4, and the gas components of the copper (gold) mineralized inclusions are mainly CO2 and N2, with a small amount of CH4. Combined with the tectonic deformation process in this area, we think that the gold-copper mineralization in Aksu Group of Changcheng system in this area mainly comes from the rocks themselves and is related to the tectonic movement. The tectonic movement made the rocks develop large fold fault zone and shear fracture zone, and Au, Cu and other useful components in the rocks were activated to form hydrothermal fluids with increasing temperature and pressure changes. The hydrothermal fluids with rich useful components such as Au and Cu were precipitated and enriched along tectonic fractures or ductile shear fractures to form copper-bearing quartz veins or gold-bearing fine quartz veins. The average salinity (wt% NaCl) of the hydrothermal fluids decreased to 2.01 in the late evolution period. The sulfur isotopes of different rocks and ores in this area are very different, which is mainly related to the different formation environment and the long-term tectonic evolution of the sedimentary basin. The Aksu Group of Changcheng System in Mesoproterozoic is an important source of denudation in the Late Jurassic-Early Cretaceous sedimentary period, which provides a certain material source for the formation of sedimentary Cu-Pb-Zn deposits. |
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