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现代地质 ›› 2016, Vol. 30 ›› Issue (6): 1179-1196.

• 矿床学与岩石学 • 上一篇    下一篇

西藏班公湖—怒江成矿带斑岩-浅成低温热液型矿床岩浆作用与成矿:以改则县东窝东铜多金属矿床为例

韦少港, 韦少港1, 唐菊兴2, 宋扬2, 刘治博2, 王勤3, 林彬2, 侯淋1, 冯军4, 李彦波5唐菊兴, 宋扬, 刘治博, 王勤, 林彬, 侯淋, 冯军, 李彦波   

  1. 1中国地质大学(北京)地球科学与资源学院, 北京100083;2中国地质科学院 矿产资源研究所,北京100037; 3成都理工大学 地球科学学院,四川 成都610059; 4中铝西藏金龙矿业股份有限公司, 西藏 拉萨850000; 5西藏自治区地质矿产勘查开发局 第五地质大队, 青海 格尔木816000
  • 出版日期:2016-12-15 发布日期:2016-12-18
  • 通讯作者: 唐菊兴,男,研究员, 博士,1964年出生, 矿产普查与勘探专业, 主要从事矿床学和固体矿产勘查与评价研究工作
  • 作者简介:韦少港, 男, 博士研究生,1989年出生, 矿产普查与勘探专业, 主要从事矿床学和固体矿产勘查与评价研究工作。Email:634719227@qq.com。
  • 基金资助:
    国土资源部行业专项“斑岩-浅成低温热液成矿系统研究及勘查评价示范——以西藏多龙整装勘查区为例”(201511017);国家自然科学青年基金项目“西藏羌塘地体南缘铁格龙南超大型浅成低温热液型铜(金)矿床保存条件研究” (41402178);国家科技基础性工作专项(2014FY121000)

Magmatism and Mineralization of Epithermalporphyry Deposit from BangonghuNujiang Metallogenic Belt: Taking Dongwodong Copper Deposit from Gerze County for Example

WEI Shaogang1, TANG Juxing2, SONG Yang2,LIU Zhibo2, WANG Qin3,LIN Bin2,HOU Lin1   

  1. 1 School of Earth Sciences and Resources, China University of Geosciences, Beijing100083, China; 2 Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing100037, China; 3 College of Earth Sciences, Chengdu University of Technology, Chengdu, Sichuan610059, China; 4 Tibet Jinlong Mining Co, Ltd, Lhasa,Tibet850000, China; 5 No 5 Geological Party, Tibet Bureau of Geology and Mineral Exploration and Development, Golmud, Qinghai816000, China
  • Online:2016-12-15 Published:2016-12-18

摘要: 西藏改则县东窝东铜多金属矿床位于西藏多龙矿集区东部,是近年来班公湖—怒江成矿带上新发现的铜多金属矿。对区内花岗闪长斑岩和花岗斑岩进行了LAICPMS锆石UPb年代学测试显示,成岩年龄为(1210±12) Ma和(1215±10) Ma,与多龙矿集区内成岩成矿年龄相近。研究区含矿斑岩显示了富集轻稀土和大离子亲石元素,亏损重稀土和高场强元素,中等Eu负异常,高铝、低镁、低钛,高Sr、低Y及Yb的岛弧岩浆岩特征,暗示矿区含矿岩浆与多龙矿集区含矿岩浆具备相同的岩浆源区。矿区含矿斑岩的锆饱和温度介于7796~8445 ℃,地球化学数据显示高Sr低Nd及低εNd(t)值特征;含矿斑岩εHf(t)为+34 ~ +111,两阶段模式年龄T2DMC为467 ~ 963 Ma;表明其与多龙矿区含矿斑岩具备相似的SrNdHf同位素特征,暗示了矿区含矿斑岩是班公湖—怒江特提斯洋洋壳向北俯冲消减背景下,由玄武质新生下地壳在较高温度条件下部分熔融形成的产物,指示班公湖—怒江洋盆于早白垩世晚期尚未关闭。野外地质调查发现,矿区发育典型斑岩铜矿蚀变分带;具备与多龙矿集区的岩石组成、矿化及蚀变、成岩成矿时代、构造环境和物质来源相类似的特征,且空间位置相近,暗示两者受控于统一的构造-岩浆成矿系统。综合分析认为,东窝东地区为多龙矿集区东延部分,具有寻找斑岩-浅成低温热液型铜(金)矿床隐伏矿体的良好潜力。

关键词: 班公湖—怒江成矿带, 东窝东铜矿床, 锆石U-Pb年龄, 地球化学, 岩浆演化, 西藏

Abstract: The Dongwodong copper deposit, located in the east of the Duolong oreconcentrated district, is a newlydiscovered porphyry copper deposit in the BangonghuNujiang metallogenic belt in Gerze County, Tibet. Zircon UPb dating results show that the granodioriteporphyries intruded at (1210±12) Ma and the graniteporphyries intruded at (1215±10) Ma, which are similar to those of the orebearing porphyries from Duolong oreconcentrated area. These porphyries are systematically more enriched in largeion lithophile elements and LREE, relatively depleted in high strength elements and HREE, and have middle negative Eu anomalies, high Al and Sr, low Mg, Ti, Y and Yb, which are consistent with those of arctype magmas worldwide. These porphyries have similar ages and geochemical features to those of ore bearing porphyries from Duolong oreconcentrated area, suggesting that they were formed in a common magma chamber. The orebearing intrusions are characterized by high TZr ranging from 7796 to 8445 ℃. Additionally, they have varying εHf(t) values ranging from +34 to +111, T2DMC values ranging from 467 to 963 Ma. According to the obtained data, we proposed that the studied porphyries were generated by partial melting of juvenile crust under the background of BangonghuNujiang Tethys oceanic crust subducting northward to Qiangtang massif and the BangonghuNujiang oceanic basin was significant sizes during the Early Cretaceous. Besides, based on field geological surveys, we suggest that this deposit show typical porphyry copper deposit alteration characteristics. Its rock composition, mineralization and alteration, ages of diagenesis and mineralization, and tectonic environment and material source are consistent with those of the deposits in Duolong oreconcentrated area. Comprehensive analysis indicates that Dongwodong copper deposit shares a great potential to discover superlarge epithermalporphyry Cu (Au, Ag) concealed ore body.

Key words: BangonghuNujiang metallogenic belt, Dongwodong copper deposit, zircon UPb age dating, geochemistry, magmatic evolution, Tibet

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