阿尔金北缘喀腊达坂火山岩型铅锌矿床研究

发布时间：2018-05-21 02:21

  本文选题：火山成因块状硫化物矿床 + 形成时代　； 参考：《地质学报》2017年08期

【摘要】：火山成因块状硫化物矿床越来越受到重视,喀腊达坂铅锌矿位于北东向阿尔金走滑断裂与东西向阿尔金北缘断裂夹持的喀腊大湾地区,是阿尔金北缘红柳沟—拉配泉金、铜、铁及多金属成矿带中唯一大型铅锌矿床。矿区主要出露奥陶系下统卓阿布拉克组火山沉积岩系,呈近东西走向,以向北中等角度倾斜的单斜层为特点,倾角30°~58°;矿化严格受火山沉积岩特定层位和岩性控制,即矿体均产于卓阿布拉克组第四亚组的中酸性火山岩(流纹岩、英安熔岩、英安质晶屑凝灰岩)中,矿体具有层状、似层状特点,产状稳定延伸大;最大矿体走向延伸超过2400m,倾向延深大于900m。主要有用组分Pb、Zn,伴生有用组分Cu、Au、Ag、S等。主要蚀变类型有黄铁矿化、硅化、绢云母化,地表氧化带形成黄钾铁钒化和褐铁矿化。矿石平均铅同位素组成为~(208)Pb/~(204)Pb=38.1169、~(207)Pb/~(204)Pb=15.6278、~(206)Pb/~(204)Pb=18.4684,显示矿石的铅具有上地壳铅和造山带铅的混合来源;矿石硫同位素组成平均+8.28‰,代表了海相沉积岩来源的硫与岩浆岩来源硫的混合;矿石稀土元素配分曲线与矿区及喀腊大湾地区中酸性火山岩的稀土元素配分曲线具有一致性或者相似,说明矿石与含矿中酸性火山岩具有一致的成因与来源;矿石微量元素特征显示Nb、Ta负异常与Ba的正异常,反映出存在海相沉积岩物质的混入,并具有岛弧成矿构造环境。含矿火山岩锆石SHRIMP U-Pb年龄482~485Ma,代表了矿床的形成时代为早古生代早奥陶世。综合喀腊达坂铅锌矿地质地球化学特征的研究,确认其属于火山成因块状硫化物矿床(VMS型)。所以,喀腊达坂铅锌矿成矿过程可以概括为:在早古生代奥陶纪早期北阿尔金洋发生向南的板块俯冲,板块俯冲作用导致俯冲带下盘的洋壳及其上的海相沉积物和俯冲带上盘的陆壳发生部分熔融,形成了中酸性岛弧型岩浆;在岩浆喷发的晚期,逐渐形成富含铅锌成矿物质的残余岩浆;当这些富含铅锌的残余岩浆发生喷发,最终形成了火山成因岩块状硫化物型铅锌矿床。火山岩型铅锌多金属矿床是阿尔金北缘喀腊大湾地区南带最重要勘查和预测类型,该火山岩型矿化带的西延区段是有利的找矿靶区。
[Abstract]:More and more attention has been paid to the massive sulfide deposits of volcanic origin. The Kaladaban lead-zinc deposit is located in the Kaladawan area, which is located in the north margin of Altun strike slip fault and the north margin fault of east-west direction Altun. It is Hongliugou-Lapaiquan gold, copper, and copper in the northern edge of Altun. The only large-scale lead-zinc deposit in the iron and polymetallic metallogenic belt. The volcanic sedimentary rocks of the Lower Ordovician Zhuobulak formation of the Lower Ordovician in the mining area are nearly east-west, characterized by a monocline inclined to the north, with a dip angle of 30 掳or 58 掳, and the mineralization is strictly controlled by the specific horizon and lithology of the volcanic sedimentary rocks. The orebodies are all occurring in the intermediate acid volcanic rocks (rhyolite, Yingan lava, Anichite tuff) of the fourth sub-formation of the Zhuobulak formation. The orebodies are stratiform, layered and stable and extensible. The largest orebody extends more than 2400m in strike and tends to extend deeper than 900m. There are mainly useful components, such as Pb ~ (2 +) Zn, associated useful components, such as Cu ~ (2 +) ~ (2 +) -Au-Ag-S, and so on. The main alteration types are pyrite silicification sericite surface oxidation zone forming yellow potassium iron vanadium and limonite. The average lead isotopic composition of the ore is as follows: (1) the average lead isotopic composition of the ore is (38.11669) ~ (38.1169) Pb ~ (-1) ~ (20) ~ (204) Pb ~ (- / -) 206B ~ (-1) ~ (15.6278) ~ (th), indicating that the lead of the ore has a mixed source of lead from the upper crust and orogenic belt, and the average sulfur isotope composition of the ore is 8.28 鈥，

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