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现代地质 ›› 2021, Vol. 35 ›› Issue (03): 599-607.DOI: 10.19657/j.geoscience.1000-8527.2021.03.02

• 矿床学 • 上一篇    下一篇

四川旺苍大河坝浅变质岩型石墨矿床地球化学特征与成因分析

段威1,2(), 唐文春1(), 黎龙昌1,2, 冉强2, 张飞1,2, 李小松1,2, 徐永胜1,2   

  1. 1.四川省地质矿产勘查开发局 化探队,四川 德阳 618000
    2.四川省深地地质勘查有限公司,四川 德阳 618000
  • 收稿日期:2020-11-25 修回日期:2021-04-02 出版日期:2021-06-23 发布日期:2021-06-24
  • 通讯作者: 唐文春
  • 作者简介:唐文春,男,教授级高级工程师,1965年出生,地球化学专业,从事矿产勘查与地球化学研究。Email: 1649500727@qq.com
    段 威,男,工程师,1988年出生,地质工程专业,从事基础地质调查与矿产勘查工作。Email: 316463467@qq.com
  • 基金资助:
    四川省地质勘查基金项目“四川省旺苍县大河坝石墨矿预查”(川自然资函[2019]477号);四川省地质矿产勘查开发局化探队科技计划项目“川北地区优质石墨矿成矿机制研究与找矿预测”(HTD202001)

Geochemical Characteristics and Genesis Analysis of Daheba Epimetamorphic Graphite Deposit in Wangcang, Sichuan Province

DUAN Wei1,2(), TANG Wenchun1(), LI Longchang1,2, RAN Qiang2, ZHANG Fei1,2, LI Xiaosong1,2, XU Yongsheng1,2   

  1. 1. Geochemistry Exploration Brigade of Sichuan Bureau of Exploration and Development of Geology and Minerals Resources,Deyang, Sichuan 618000, China
    2. Sichuan Deep Resource Geological Exploration Co., Ltd.,Deyang, Sichuan 618000, China
  • Received:2020-11-25 Revised:2021-04-02 Online:2021-06-23 Published:2021-06-24
  • Contact: TANG Wenchun

摘要:

大河坝石墨矿是川北米仓山南缘石墨矿带新发现的大型显晶质石墨矿床。研究了该矿床的地质特征和矿石主量、微量及稀土元素地球化学特征,结果表明:含矿岩层为副变质岩,矿区石墨矿体原岩沉积于缺氧的还原环境,原岩为一套含碳质黏土质细—粉砂岩及含碳质泥灰岩组合。微量元素特征指示矿体原岩由近海陆源碎屑物沉积形成,沉积水体主要为盐度较低的、混合不均匀的淡水—半咸水。矿石ΣREE平均值为150×10-6,与泥灰岩相近;δCe值平均为0.91,呈弱负异常,δEu值平均为0.67,呈负异常,具滨海潮坪相沉积特征。含矿岩石δ13C值为-21.4‰~-19.0‰,平均为-19.86‰,表明成矿碳质来源主要为有机碳,并混合了部分无机碳。矿床成因类型为沉积变质型,其变质作用可能包括多次区域变质作用并叠加了混合岩化作用。

关键词: 晶质石墨, 地球化学特征, 有机碳, 沉积变质型, 旺苍大河坝

Abstract:

Daheba graphite deposit is a newly discovered large phanerocrystalline graphite deposit in the southern margin of Micangshan, northern Sichuan. The geological characteristics of the deposit and the geochemical characteristics of major, trace elements and rare earth elements of minerals are studied in the paper. The results show that the ore bearing strata are parametamorphic rocks. The original rock deposition of graphite ore body in Daheba mining area is under anoxic reduction environment, and the protolith is composition of carbonaceous clayey fine to silt stone and carbonaceous marlite. The characteristics of trace elements indicate that the ore body is mainly composed of terrigenous clastic sediments. The sedimentary water is mainly fresh to brackish water with low salinity and uneven mixing. The average value of ∑REE of the ore is 150×10 -6, which is similar to marlite; The average value of δCe is 0.91, Ce indicating weak negative anomaly; The average value of δEu is 0.67, Eu is negative anomaly and has the characteristics of coastal tidal flat facies deposition; The δ 13C values of the ore bearing rocks ranged from -21.4‰ to -19.0‰, with an average of -19.86‰, indicating that the main source of metallogenic carbon is organic carbon, which may be mixed with some inorganic carbon. The genetic type of the deposit is sedimentary metamorphic. The metamorphism may be multiple regional metamorphism and superimposed migmatization.

Key words: crystalline graphite, geochemical characteristics, organic carbon, sedimentary metamorphic type, Daheba in Wangcang County

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