CAJ | 학술논문

提对滇西九顶山铜钼矿床主要的含矿花岗斑岩开展了系统的年代学、岩石地球化学以及全岩Sr-Nd-Hf同位素的分析工作。LA-ICP-MS锆石U-Pb定年结果表明,九顶山花岗斑岩成岩年龄为34.5~34.9 Ma,与已有的成矿年龄(33.9~35.3 Ma)一致或略早于成矿年龄,处在滇西新生代富碱岩浆活动高峰期内(45~30 Ma),属于青藏高原碰撞造山带的晚碰撞转换成矿作用(40~26 Ma)的产物。详细的岩石地球化学研究表明,研究区花岗斑岩有高硅(SiO2=62.86%~71.57%)、高钾(K2O/Na2O=1.64~2.78)和富碱(K2O+Na2O=8.98%~11.28%)的特点,属于钾玄岩系列岩石。岩体轻稀土元素富集(LREE/HREE=4.84~7.64),具有轻微的负铕异常(δEu=0.82~0.93),富集大离子亲石元素(Rb、Ba、Th、U)和亏损高场强元素(Nb、Ta、Zr、Hf)。Sr-Nd-Hf同位素的研究分析显示岩浆源区起源于“EMII型”富集地幔,“EMII型”富集地幔岩浆在上涌的过程中受到地壳物质的混染,形成壳幔混合源富钾含矿岩浆。
제대전서구정산동목광상주요적함광화강반암개전료계통적년대학、암석지구화학이급전암Sr-Nd-Hf동위소적분석공작。LA-ICP-MS고석U-Pb정년결과표명,구정산화강반암성암년령위34.5~34.9 Ma,여이유적성광년령(33.9~35.3 Ma)일치혹략조우성광년령,처재전서신생대부감암장활동고봉기내(45~30 Ma),속우청장고원팽당조산대적만팽당전환성광작용(40~26 Ma)적산물。상세적암석지구화학연구표명,연구구화강반암유고규(SiO2=62.86%~71.57%)、고갑(K2O/Na2O=1.64~2.78)화부감(K2O+Na2O=8.98%~11.28%)적특점,속우갑현암계렬암석。암체경희토원소부집(LREE/HREE=4.84~7.64),구유경미적부유이상(δEu=0.82~0.93),부집대리자친석원소(Rb、Ba、Th、U)화우손고장강원소(Nb、Ta、Zr、Hf)。Sr-Nd-Hf동위소적연구분석현시암장원구기원우“EMII형”부집지만,“EMII형”부집지만암장재상용적과정중수도지각물질적혼염,형성각만혼합원부갑함광암장。
In this study, the authors carried out a comprehensive research including zircon U-Pb dating, petrogeochemical investigation and Sr-Nd-Hf isotope analysis of the granite porphyry related to the Jiudingshan Cu-Mo deposit in western Yunnan. LA-ICP-MS zircon U-Pb chronology indicates that the porphyry was emplaced at 34.5?34.9 Ma, consistent with or slightly earlier than the formation of the Cu-Mo deposit (33.9?35.3 Ma) and similar in time to the peak of Cenozoic alkali-rich magmatic activity <br> (45?30 Ma) in western Yunnan, indicating that they were formed by the ore-forming process in the period of late-collisional transformation (40?26 Ma). The granite porphyry is silica-rich (SiO2=62.86%?71.57%), potassium-rich (K2O/Na2O=1.64?2.78) and alkali-rich (K2O+Na2O = 8.98%?11.28%), belonging to shoshonitic series peraluminous granite, with the characteristics of LREE enrichment, HREE depletion, and weak negative Eu anomaly (δEu=0.82?0.93). The porphyry is enriched in LILEs such as Rb, Ba, Th and U, and depleted in HFSEs such as Nb, Ta, Zr and U. Sr?Nd?Hf isotopes imply that the magma originated from the EMII which was contaminated by crustal materials in the process of magmatic upwelling to form a potassium-rich ore-bearing magma with mixed sources of the crust and the mantle.