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姚雪,李文昌,刘学龙,张娜,杨富成,彦廷龙,王帅帅,罗应.滇西北格咱岛弧带南缘铜厂沟斑岩铜钼矿床花岗闪长斑岩地球化学特征、锆石U-Pb年龄及其地质意义[J].地质通报,2017,(10):1800-1813.
滇西北格咱岛弧带南缘铜厂沟斑岩铜钼矿床花岗闪长斑岩地球化学特征、锆石U-Pb年龄及其地质意义    点此下载全文
姚雪1  李文昌1  2  刘学龙1  张娜1  杨富成1  彦廷龙1  王帅帅1  罗应1
1. 昆明理工大学, 云南 昆明 650093;
2. 中国地质调查局成都地质调查中心, 四川 成都 610081
基金项目:云南省科技领军人才计划项目《西南“三江”叠合成矿作用与成矿预测》(编号:2013HA001)、国家自然科学基金项目《云南格咱岛弧印支期斑岩型铜矿床变化与保存研究》(批准号:41502076)、云南省教育厅科学研究基金项目《云南格咱岛弧成矿带斑岩型铜矿成矿系统研究》(编号:2015Y066)
DOI:
摘要:
      云南格咱岛弧构造-岩浆成矿带是义敦岛弧的重要组成部分,属于西南三江地区铜多金属矿床富集区之一。对格咱岛弧南缘铜厂沟成矿斑岩的岩石学、地球化学特征及锆石U-Pb年龄进行了研究,系统分析了区内花岗岩的岩石成因、形成的构造环境及成岩成矿的地球动力学背景。铜厂沟成矿斑岩主要为花岗闪长斑岩,用LA-ICP-MS测得其中锆石的206Pb/238U年龄为87.62±0.59Ma。岩石地球化学特征表明,铜厂沟花岗闪长斑岩具有高硅、富碱、富钾的特点,属于高钾钙碱性岩石系列;岩石具有较高的稀土元素总量;富集轻稀土元素,轻、重稀土元素分馏明显,δEu为0.89~0.97,具较弱的负异常;微量元素特征表明,岩石富集大离子亲石元素K、U、Th、Rb、Ba、Sr,亏损高场强元素Nb、Ta、P、Ti;大离子亲石元素的富集和Nb、Ta等高场强元素的亏损,说明岩浆主要来源于壳源物质的部分熔融。本区花岗岩形成于碰撞后与伸展构造的转换阶段,属于碰撞造山过程的产物。碰撞诱发的岩石圈地幔物质上涌导致地壳发生部分熔融作用,形成富钾的初始含矿岩浆,岩浆沿深大断裂上升侵位最终形成了格咱岛弧燕山晚期的构造-岩浆作用及成矿事件。
关键词:LA-ICP-MS锆石U-Pb年龄  花岗闪长斑岩  地球化学特征  成矿机制  铜厂沟  云南
Geochemistry and zircon U-Pb age of the Tongchanggou porphyry Cu-Mo deposit on the southern margin of Geza arc, northwest Yunnan Province, and its geological significance    Download Fulltext
YAO Xue1  LI Wenchang1  2  LIU Xuelong1  ZHANG Na1  YANG Fucheng1  YAN Tinglong1  WANG Shuaishuai1  LUO Ying1
1. Kunming University of Science and Technology, Kunming 650093, Yunnan, China;
2. Chengdu Geological Survey Center of China Geological Survey, Chengdu 610081, Sichuan, China
Fund Project:
Abstract:
      The Geza tectonic-magmatic belt is an important part of Yidun arc and also an important ore concentration area of copper polymetallic deposits in the Sanjiang region of southwest China. Based on the study of petrologic and geochemical characteristics and zircon U-Pb geochronology of the Tongchanggou ore-forming porphyry on the southern margin of Geza arc, the authors systemati-cally analyzed the petrogenesis, tectonic environment, diagenesis and metallogenic geodynamic background of the granite. The rock type of Tongchanggou metallogenic porphyry is granodiorite porphyry, the research results of the zircon U-Pb geochronology show that the age of emplacement and crystallization of the magma is 87.62±0.59Ma (MSWD=0.52) by LA-ICP-MS method. Petrograph-ic and lithogeochemical characteristics indicate that Tongchanggou granodiorite porphyry has characteristics of high silicon (63.02%~74.06%), high alkali (K2O+Na2O=6.97%~8.79%), and rich K (K2O/Na2O=0.71~2.13). The rocks belong to high-K calc-alkaline rock series enriched in light rare earth elements. The fractionation between LREE and HREE is obvious. δEu values are 0.89~0.97 with a weak negative anomaly. The analytical results of trace elements show that the rocks are enriched in large ion lithophile elements of K, U, Th, Rb, Ba, Sr, and depleted in high field strength elements of Nb, Ta, P, Ti, suggesting that the formation of magma might have been derived from the partial melting of crust materials. The granite was formed in the conversion stage of post-collision and ex-tensional tectonics, belonging to the product of the collision orogenic process. The collision induced upwelling of the lithospheric man-tle which led to partial melting of the crust and formed the potassium-rich and ore-bearing initial magma. Magma rising and intrusion along the deep faults eventually triggered the late Yanshanian tectonic-magmatic and metallogenic events in Geza area.
Keywords:LA-ICP-MS zircon U-Pb age  granodiorite porphyry  lithogeochemical characteristics  mineralization mechanism  Tongchanggou  Yunnan
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