ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    东准噶尔莫钦乌拉地区石墨矿成岩成矿时代及矿床成因

    Diagenetic and Metallogenic Ages and Genesis of Graphite Deposits in the Moqinwula Area, Eastern Junggar

    • 摘要: 新疆东准噶尔莫钦乌拉地区马依当、吐尔库里、克音南等石墨矿是近年来新发现的具工业价值的矿床。笔者以吐尔库里石墨矿为研究对象,开展 LA-ICP-MS锆石U-Pb定年与岩石地球化学分析。结果显示,该矿赋矿地层形成时代为(334±9)Ma,石墨成矿时代为313 Ma。石墨矿石富集Rb、Ba、Pb、Sr等亲石元素,亏损 Th、Nb、Ta、Ti等高场强元素;稀土元素总量偏低,ΣREE值为52.16×10−6~134.21×10−6,平均值为81.71×10−6,指示含矿岩石沉积物质源于陆源碎屑岩,形成于滨浅海–浅海缺氧还原沉积环境。综合研究认为,东准噶尔莫钦乌拉地区石墨矿赋矿地层为下石炭统姜巴斯套组,纠正前人将其归为上志留统—下泥盆统红柳沟组的认识;该矿床属接触变质型石墨矿,后期构造活动叠加岩浆侵入改造,促使下石炭统姜巴斯套组含碳沉积岩系中有机质活化,经脱氧、脱氢反应并重结晶,最终形成晶质石墨。

       

      Abstract: The Mayidang, Tu'erkuli, Keyinnan and other graphite deposits in the Moqinwula area of the East Junggar Basin, Xinjiang, are newly discovered deposits with industrial value in recent years. Taking the Tu'erkuli graphite Deposit as the research object, this study carried out LA-ICP-MS zircon U-Pb dating and petrogeochemical analysis. Chronological results show that the ore-hosting stratum of this deposit formed at 334±9 Ma, and the graphite mineralization occurred at 313 Ma. The petrogeochemical characteristics are as follows: the graphite ore is enriched in lithophile elements such as Rb, Ba, Pb and Sr, and depleted in high field strength elements (HFSEs) including Th, Nb, Ta and Ti; the total content of rare earth elements (REEs) is relatively low, with ΣREE ranging from 52.16×10−6 to 134.21×10−6 and an average of 81.71×10−6. These features indicate that the sedimentary materials of the ore-bearing rocks were derived from terrigenous clastic rocks, and the rocks formed in a neritic-epicontinental anoxic reducing sedimentary environment. Comprehensive research suggests that the ore-hosting stratum of graphite deposits in the Moqinwula area of East Junggar is the Lower Carboniferous Jiangbasitao Formation, which corrects the previous understanding that it belonged to the Upper Silurian-Lower Devonian Hongliugou Formation. This deposit is a contact metamorphic graphite deposit. Its genetic mechanism is as follows: under the superimposed transformation of late tectonic activities and magmatic intrusion, the organic matter in the carbon-bearing sedimentary rock series of the Lower Carboniferous Jiangbasitao Formation was activated, undergoing deoxidation and dehydrogenation reactions followed by recrystallization, and finally forming crystalline graphite.

       

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