Genesis of the late Ordovician Kukaazi PbZn deposit in the western Kunlun orogen, NW China: New insights from in-situ trace elemental compositions of base metal sulfides
Genesis of the late Ordovician Kukaazi PbZn deposit in the western Kunlun orogen, NW China: New insights from in-situ trace elemental compositions of base metal sulfides
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中国西昆仑造山带晚奥陶世库卡孜铅锌矿床成因：贱金属硫化物原位微量元素组成的新认识
DOI：
10.1016/j.jseaes.2019.103995
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发表时间：
2019
影响因子：
3
通讯作者：
Xing-Chun Zhang
中科院分区：
文献类型：
--
作者：
Cheng-Biao Leng;Wei Wang;Lin Ye;Xing-Chun Zhang
昆仑西造山带库卡子铅锌矿是新近发现的。该矿床由3个矿块（KI ~ KIII）组成，赋存于中元古代变质岩中。矿石主要由闪锌矿、方铅矿、黄铜矿和白钨矿组成。本文对KI矿块和KII矿块硫化物矿石中闪锌矿和方铅矿的原位LA-ICP-MS微量元素组成进行了研究，以阐明矿床形成及其区域构造成矿意义。KI矿块闪锌矿中Fe、Mn、Co、Cu、Bi、Sn、Sb的含量高于KII矿块闪锌矿。尽管如此，来自这两个矿块的闪锌矿的成分与来自典型矽卡岩矿床的闪锌矿相似。KI矿块方铅矿与KII矿块方铅矿组成不同，其Ag、Cd、Tl含量较高，Sb含量较低。这种差异可能是由于两个矿块的成矿温度不同造成的。根据共存闪锌矿-方铅矿对间的Cd分配系数，KI矿块的硫化矿形成温度（265 ~ 387℃）可能高于KII矿块（229 ~ 251℃）。结合前人研究，认为库卡子铅锌成矿与远端矽卡岩有关，形成于大陆弧环境。该矿床的发现，预示着西山金矿是未来中国西北斑岩/夕卡岩类PbZn （-Cu-W）矿产勘查的有利区域。
The Kukaazi Pb-Zn deposit was recently discovered in the western Kunlun orogen (WKO), NW China. This deposit consists of three ore blocks (KI to KIII) hosted in Mesoproterozoic metamorphosed rocks. Ores are mainly composed of sphalerite, galena, chalcopyrite and scheelite. Here we present in-situ LA-ICP-MS trace elemental compositions of sphalerite and galena of sulfide ores from ore blocks KI and KII, to shed light on the ore formation and its regional tectono-metallogenic implications. Sphalerite from ore block KI contains higher contents of Fe, Mn, Co, Cu, Bi, Sn, and Sb than sphalerite from ore block KII. Nonetheless, sphalerite from the two ore blocks has compositions similar to the sphalerite from typical skarn deposits. Galena from ore block KI is compositionally different from galena from ore block KII, and has relatively high Ag, Cd and Tl contents and low Sb content. Such differences are probably due to different ore-forming temperatures in these two ore blocks. Based on the Cd partition coefficient between the co-existing sphalerite-galena pairs, sulfide ores in ore block KI may have formed under higher temperatures (265–387 ℃) than those in ore block KII (229–251 ℃)..Combined with previous studies, we propose that the Pb-Zn mineralization at Kukaazi was distal skarn related and formed in a continental arc setting. Discovery of this deposit implies that WKO is a promising area for future porphyry/skarn-related PbZn (-Cu-W) mineral exploration in northwestern China.