| 长安金矿区碱性岩锆石U-Pb年代学、微量元素、Hf同位素特征及其地质意义 |
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| 引用本文： | 龙天祥,何小虎,刘飞,李宗勇,王玉朝,赵俊,李云飞,王长兵,曹原.长安金矿区碱性岩锆石U-Pb年代学、微量元素、Hf同位素特征及其地质意义[J].吉林大学学报(地球科学版),2019,49(6):1607-1627. |
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| 作者姓名： | 龙天祥 何小虎 刘飞 李宗勇 王玉朝 赵俊 李云飞 王长兵 曹原 |
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| 作者单位： | 1. 云南省地质调查院, 昆明 650216;2. 云南大学资源环境与地球科学学院, 昆明 650091;3. 云南省核工业二○九地质大队, 昆明 650032 |
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| 基金项目： | 国家自然科学基金项目（41702084）；云南省应用基础研究计划项目（2017FD063）；中国地质调查局项目（121201010000150007） |
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| 摘 要： | 长安金矿是哀牢山成矿带南段典型的大型金矿床之一，矿区内发育大量的碱性岩脉。本文通过对矿区内碱性岩锆石U-Pb年代学、微量元素及Hf同位素的研究，限定碱性岩的形成时间、来源和成因，并进一步探讨该金矿床的成因。LA-ICP-MS锆石U-Pb年龄表明长安金矿区碱性岩主要形成于晚始新世（37.0~35.0 Ma）。碱性岩锆石微量元素、Hf同位素和结晶温度等表明其主要来自下地壳火成岩区，在形成过程中存在少量1 648.5~34.8 Ma不同时期的上地壳沉积岩物质的加入，碱性岩是哀牢山韧性剪切活动诱发基性-超基性熔体发生底侵作用，并加热下地壳发生部分熔融的产物。结合前人成矿流体稳定同位素研究结果，提出碱性岩的形成与金矿化是在印度-欧亚板块碰撞下，青藏高原物质东向逃逸诱发哀牢山韧性剪切活动构造背景下的独立产物，他们之间没有直接的成因联系，仅仅是同一构造-地质作用的不同表现形式。
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| 关 键 词： | 长安金矿 碱性岩 锆石年代学 微量元素 Hf同位素 |
| 收稿时间： | 2018-10-29 |
Zircon U-Pb Geochronology,Trace Element,Hf Isotope of Alkaline Rocks from Chang'an Gold Deposit and Its Geological Implication |
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| Long Tianxiang,He Xiaohu,Liu Fei,Li Zongyong,Wang Yuchao,Zhao Jun,Li Yunfei,Wang Changbing,Cao Yuan.Zircon U-Pb Geochronology,Trace Element,Hf Isotope of Alkaline Rocks from Chang'an Gold Deposit and Its Geological Implication[J].Journal of Jilin Unviersity:Earth Science Edition,2019,49(6):1607-1627. |
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| Authors: | Long Tianxiang He Xiaohu Liu Fei Li Zongyong Wang Yuchao Zhao Jun Li Yunfei Wang Changbing Cao Yuan |
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| Institution: | 1. Geological Survey Institute of Yunnan Province, Kunming 650216, China;2. School of Resource Environment and Earth Science, Yunnan University, Kunming 650091, China;3. No. 209 Geological Party, Geological Bureau of Yunnan Nuclear Industry, Kuming 650032, China |
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| Abstract: | The Chang'an gold deposit,is one of the large classic gold deposits in the south Ailaoshan metallogenic belt, where many vein-type alkaline rocks appeared. In this paper,we present new data of the zircon U-Pb geochronology,trace element,and Hf isotope of these alkaline rocks from the Chang'an gold deposit to constrain their age and origin;furthermore,to discuss the formation mechanism of the gold deposit.The LA-ICP-MS zircon U-Pb isotope data show that these alkaline rocks formed in the Late Eocene(37.0-35.0 Ma).According to the chemistry of trace element,Hf isotope,and zircon saturation temperature,they were mainly derived from igneous zone in the lower crust,but a small amount of sediment material was formed during 1 648.5-34.8 Ma in the upper crust. Further,these alkaline rocks are the results of the partial melting of lower crust which were heated by the under-plated hot basic-ultrabasic melt induced by the ductile shear activity of Ailaoshan. Combined with the previous data of the stable isotopes of ore-forming fluid,we suggest that the forming of alkaline rocks and gold mineralization are independent events which occurred under the same geological setting,and the ductile shear activity of Ailaoshan was triggered by the southeastward escape of Tibetan Plateau during the collision of Indian plate and Euro-Asia plate. |
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| Keywords: | Chang'an gold deposit alkaline rocks zircon geochronology trace element Hf isotope |
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