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现代地质 ›› 2013, Vol. 27 ›› Issue (3): 577-584.

• 矿床学与地球化学 • 上一篇    下一篇

青海德尔尼铜(锌钴)矿床Re-Os年龄及地质意义

焦建刚1,鲁浩2,孙亚莉3,黄喜峰1,段俊1   

  1. 1长安大学 地球科学与资源学院, 陕西 西安710054;
    2西安地质矿产研究所, 陕西 西安710054;
    3中国科学院 广州地球化学研究所同位素地球化学国家重点实验室,广东 广州510640
  • 收稿日期:2012-07-07 修回日期:2012-10-07 出版日期:2013-06-07 发布日期:2013-06-08
  • 作者简介:焦建刚,男,副教授,1976年出生,矿物学、岩石学、矿床学专业,主要从事矿床地质方面的教学与科研工作。Email: jiangang@chd.edu.cn。
  • 基金资助:

    国家自然科学基金项目“甘肃龙首山地区与铜镍成矿有关的幔源岩浆事件重建”(41072058); 国土资源部公益性行业科研专项(200911007,201011058)。

Re-Os Dating for Derni Cu(Zn-Co) Ore Deposit in Qinghai Province, China and Its Geological Implication

JIAO Jian-gang1, LU Hao2, SUN Ya-li3, HUANG Xi-feng1, DUAN Jun1   

  1. 1School of Earth Science and Resources, Chang'an University, Xi'an, Shaanxi710054 , China;
    2Xi'an Institute of Geology and Mineral Resource, Xi'an, Shaanxi710054, China;
    3Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong510640, China
  • Received:2012-07-07 Revised:2012-10-07 Online:2013-06-07 Published:2013-06-08

摘要:

东昆仑德尔尼大型铜(锌钴)矿是赋存在蛇绿岩中的块状硫化物矿床,8件块状硫化物矿石的Re-Os同位素等时线年龄为(295.5±7.2) Ma,略小于矿区玄武质熔岩的锆石U-Pb平均年龄(308.2±4.9) Ma,矿床形成于晚石炭世—早二叠世,属于阿尼玛卿洋盆扩张期。成矿时代早于矿区北部印支期花岗岩,证明德尔尼矿床的成因与印支期花岗岩无直接关系。矿石组构、矿物组合和岩石地球化学研究指示,矿床为海底喷流沉积-热液叠加成矿,具有类似于塞浦路斯型块状硫化物矿床的构造背景和矿物组合特征。矿区及外围填图发现,德尔尼铜矿体主要产出在角砾状蛇纹岩中,部分位于蛇纹岩与含碳铁硅质岩之间,这种特殊的赋矿层位可能与晚古生代特提斯洋的快速扩张、岩浆补给少、变质橄榄岩迅速抬升有关。

关键词: 块状硫化物矿床, Re-Os同位素定年, 蛇绿岩, 德尔尼, 东昆仑

Abstract:

Derni massive sulfide Cu(Zn-Co) deposit is mainly wrapped by ophiolite in East Kunlun Mountains, and 8 massive sulfide ores give an isochronal age of (295.5±7.2)Ma by Re-Os isotope, which is a little later than zircon U-Pb age (308.2±4.9) Ma of the basalt in the mining area. The diagenesis and metallogenic epoch is between Late Carboniferous and Early Permian. It is older than the Indo-Chinese epoch granite in the north side of the mining area, suggesting no direct genesis relationship between granite and Derni Cu(Zn-Co) ore deposit. According to the texture and structure of the ores, mineral compositions and various geochemistry data, the genesis of Derni Cu(Zn-Co) ore deposit can be summarized as submarine exhalation-sedimentary mineralization and experienced later hydrothermal superimposition, which is similar to Cyprus-type VMS deposit by tectonic setting and mineral compositions. From mapping and borehole logging, the main ore bodies of Derni Cu(Zn-Co) ore deposit lay in brecciaous serpentinite or between brecciaous serpentinite and carbonaceous Fe-Si rock, which is different from any other VMS deposits in the world, and the special phenomenon may be caused by quick spreading of Late Paleozoic Tethyan middle ocean ridge, lack of enough mafic magma replenishment, accompanied by rapid ascending of meta-peridotite.

Key words: massive sulfide deposit, Re-Os isotope dating, ophiolite, Derni, East Kunlun Mountains

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