柴北缘地区的两类块状硫化物矿床——Ⅱ.青龙滩式VHMS型Cu-S矿床  

Two types of massive sulfide deposits along northern margin of Qaidam basin, Qinghai Province: Ⅱ. Qinglongtan-style VHMS Cu-S deposits

作　　者：张德全[1] 党兴彦[2] 李大新[1] 丰成友[1] 佘宏全[1] 李进文[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]青海省地质调查院,青海西宁810012

出　　处：《矿床地质》2005年第6期575-583,共9页Mineral Deposits

基　　金：国家科技攻关计划(2003BA612A_07);国家自然科学基金(40372051)的联合资助

摘　　要：文章综述了柴北缘地区的VHMS型Cu_S矿床———青龙滩式矿床,指出其容矿岩石为加里东造山带中被改造过的岛弧火山岩,该矿床中含铜硫化物矿层形成后不但遭受过构造的强烈改造,而且也受后期矽卡岩化的改造和叠加。放射性同位素测年结果表明,青龙滩矿床的主岩———安山岩形成于晚寒武世(514.2±8.5)Ma,后期的矽卡岩矿化大约发生在290Ma。柴北缘加里东造山带中既产有VHMS型Cu_S矿床(如青龙滩矿床),也产有SEDEX型Pb_Zn矿床(如锡铁山矿床),两者的成矿地质构造背景和形成年龄不相同。柴北缘地区的早古生代洋(海)盆于晚寒武世俯冲消减,出现岛弧,并形成青龙滩等VHMS型Cu_S矿床,之后(早奥陶世),发生弧后拉张,形成弧后盆地及锡铁山等SEDEX型铅锌矿床。The Qinglongtan-style deposits refer to the VHMS-type Cu-S deposits in island arc volcanic rocks of the Caledonian orogenic belt along the northern margin of Qaidam basin. The copper-bearing sulfide horizon of the Qinglongtan deposit underwent not only intense structural reformation but also superimposition of skarn-type mineralization after the formation of massive sulfide ores. Dating data show that andesite, the host rock of the Qinglongtan deposit, was formed during Late Cambrian [ （514.2 ± 8.5） Ma], and skarn mineralization took place at about 290 Ma. SEDEX Pb-Zn deposits such as the Xitieshan Pb-Zn deposit and VHMS Cu-S deposits such as the Qinglongtan Cu-S deposit occur in this Caledonian orogenic belt, but their geological settings and formation ages are different. The subduction of the Early Paleozoic ocean/sea occurred in Late Cambrian and the island arc was formed in the northern margin of Qaidam basin where the Qinglongtan and other VHMS-type Cu- S deposits occurred. After that, this region was subjected to extension and transformed into a backarc basin, where the Xitieshan and other SEDEX-type Pb-Zn deposits were formed during Early Ordovician.

关 键 词：地质学 VHMS型Cu-S矿床 青龙滩式 柴北缘 

分 类 号：P618.41[天文地球—矿床学]