黑龙江佳木斯地块典型石墨矿床含矿岩石地球化学特征及成矿时代

发布时间：2018-12-07 12:51

【摘要】：佳木斯地块位于东北亚早前寒武纪陆块,区内变质岩系发育,是重要的晶质石墨富集地带。文章通过对佳木斯地块典型的萝北云山和鸡西柳毛石墨矿床含矿岩石进行SHRIMP锆石U-Pb年龄测定,结果表明:变质锆石和碎屑锆石207Pb/206Pb年龄分别为(1855±5)~(1979±13)Ma和(476±9)~(575±12)Ma。通过地球化学特征分析,萝北云山石墨矿和鸡西柳毛石墨矿含矿岩石富集Rb、Ba等大离子亲石元素和Zr、Hf、Th、U、Nb、Ta等高场强元素,含矿岩石Rb/Sr平均值均高于陆壳值0.24,表明循环沉积作用较弱;Sr/Ba比值较低,表明岩浆来源于陆壳重熔,显示以陆源物质为主;V/Cr平均值为4.58,V/(Ni+V)平均值为0.90,显示弱还原环境;两处典型矿床轻稀土元素含量均高于重稀土元素,萝北云山矿床负Eu异常明显,显示陆棚浅海沉积特征,鸡西柳毛矿床正Ce异常明显,显示海源物质为主的浅海沉积特征。研究区混合花岗岩脉的稀土元素配分曲线具有正Eu异常,显示出外来岩浆热液交代岩石特征。因此,佳木斯地块典型石墨矿床含矿岩石在古元古代晚期经受区域性高温高压变质作用,后经过早古生代强烈的泛亚构造作用,在构造岩浆侵入背景下进一步增生形成巨晶鳞片状石墨。
[Abstract]:The Jiamusi block is located in the early Precambrian continental block in Northeast Asia, and the metamorphic rock system is developed in the area, which is an important crystalline graphite enrichment zone. In this paper, the SHRIMP zircon U-Pb dating of the typical Yunshan and Jixi Liumao graphite deposits in the Jiamusi block is studied. The results show that the 207Pb/206Pb ages of metamorphic zircon and clastic zircon are (1855 卤5) ~ (1979 卤13) Ma and (476 卤9) ~ (575 卤12) Ma., respectively. Based on the analysis of geochemical characteristics, the ore-bearing rocks of Yunshan graphite ore and Jixi Liumao graphite ore in Luobei are enriched with large ion lithophile elements such as Rb,Ba and high field strength elements such as Zr,Hf,Th,U,Nb,Ta. The average Rb/Sr of ore-bearing rocks is higher than that of continental crust 0.24, which indicates that the cyclic sedimentation is weak. The Sr/Ba ratio is low, which indicates that the magma originated from the continental crust remelting, and the V/Cr mean value is 4.58 V / (Ni V) 0.90, indicating a weak reduction environment. The content of light rare earth elements in two typical deposits is higher than that of heavy rare earth elements. The negative Eu anomaly of Yunshan deposit in Luobei is obvious, which shows the characteristics of continental shelf shallow sea sedimentation and the positive Ce anomaly of Jixi Liumao deposit, which shows the shallow sea sedimentary characteristics dominated by sea source material. The REE distribution curve of the mixed granite veins in the study area has positive Eu anomaly, showing the metasomatic rock characteristics of extraneous magmatic hydrothermal solution. Therefore, the ore-bearing rocks of the typical graphite deposits in the Jiamusi block underwent regional high-temperature and high-pressure metamorphism in the late Paleoproterozoic, and then underwent a strong pan-subtectonic process in the early Paleozoic. In the background of tectonic magma intrusion, megacrystalline flake graphite was further proliferated.
【作者单位】：辽宁工程技术大学;辽宁省化工地质勘查院;辽宁省地质矿产调查院;
【基金】：中国地质调查局项目(DD20160049-[2017]-14)资助
【分类号】：P619.252

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