卫宁北山库井沟石墨矿床地质地球化学特征及成因  

Geochemical Characteristics and Genesis of the Kujinggou Graphite Deposit in Weining Beishan,Ningxia

作　　者：李海峰 姜喜冬 于海滨 海连富 刘向东 LI Haifeng;JIANG Xidong;YU Haibin;HAI Lianfu;LIU Xiangdong(Mineral and Geological Institute of Ningxia Hui Autonomous Region,Yinchuan 750021,Ningxia,China)

机构地区：[1]宁夏回族自治区矿产地质调查院,宁夏银川750021

出　　处：《西北地质》2024年第5期181-191,共11页Northwestern Geology

基　　金：宁夏自然科学基金项目“宁夏中卫市单梁山石墨矿成矿特征及找矿方向研究”(2020AAC03456)资助。

摘　　要：库井沟石墨矿床位于宁夏卫宁北山-内蒙古阿拉善左旗南部地区,矿体赋存于下石炭统臭牛沟组区域变质岩中,原岩为滨浅海相陆源碎屑岩和碳酸盐岩沉积建造。矿体产状与地层产状近于一致,呈平行层状分布于变质石英砂岩中,走向近东西。矿石主要为含石墨碳质板岩,固定碳含量平均为5.53%。石墨主要呈不规则鳞片状单晶或呈块状聚晶集合体产出,多数大于1μm。石墨矿石整体表现为低Si、低碱、高烧矢量的特点,大离子亲石元素Rb、Ba、Sr富集石墨矿石∑REE为101×10^(-6)~137×10^(-6),平均为117×10^(-6),围岩的∑REE为42×10^(-6)。石墨矿石和围岩的稀土元素分异程度较高,轻稀土元素明显富集,并都具有δEu和δCe负异常。石墨矿石的C同位素值变化很小,集中在-24.3‰~-24.0‰,表明库井沟矿床中碳质来源主要为有机物,并掺杂部分无机碳。库井沟石墨矿床属于区域变质型,滨浅海相-泻湖相沉积建造是其形成的物质基础,石墨的形成与区域变质变形作用密切相关。The Kujinggou graphite deposit is located in the southern area of Weining Beishan,Ningxia and Alashan Zuoqi,Inner Mongolia.The ore body is hosted in the regional metamorphic rocks of the Lower Carboniferous Chouniugou Formation,and the original rocks are sedimentary construction of shallow marine terrestrial clastic and carbonate rocks.The ore body is distributed in parallel layers in the metamorphic quartz sandstone,which is basically consistent with the stratigraphic production,with a near east-west orientation.The ore is mainly graphite-bearing carbonaceous slate with an average fixed carbon content of 5.53%.Graphite is mainly produced as irregularly scaled single crystals or as massive polycrystalline assemblages,mostly larger than 1μm.Graphite ore is characterized by low Si,low alkali and high LOI as a whole,and trace element analysis shows enrichment of Rb,Ba and Sr.TheΣREE of graphite ore ranges from 101×10^(-6) to 137×10^(-6),with an average of 117×10^(-6),and theΣREE of the host rocks is 42×10^(-6).The REE distribution patterns of both graphite ore and host rocks are high on the left and low on the right,and theΣREE in graphite ore is higher than that in host rocks,which shows a high degree of REE differentiation in ore and host rocks in general,and a significant enrichment of LREE.The negative anomalies of Eu and Ce are obvious.The carbon isotope values of the graphite ore vary very little and are concentrated between−24.3‰and−24.0‰,indicating that the carbonaceous source is mainly organic with some inorganic carbon involved.The genesis type of this deposit is regional metamorphic,and the shallow marine and lagoonal sedimentary environment makes the material basis for the graphite formation in Kujinggou,graphite formation is closely related to regional metamorphic deformation.

关 键 词：石墨矿床 地质地球化学 矿床成因 库井沟 卫宁北山 

分 类 号：P619.252[天文地球—矿床学]