| 杜菊民,景永波,孙晨,刘平,李双喜,陈诚.坦桑尼亚纳钦圭阿石墨成矿带地质特征及成因初析[J].地质找矿论丛,2021,36(2):239-246 |
| 坦桑尼亚纳钦圭阿石墨成矿带地质特征及成因初析 |
| Geological Characteristics and Preliminary Genetic Analysis of Nachingwea Graphite ore Belt, Tanzania |
| 投稿时间：2020-12-03 |
| DOI：10.6053/j.issn.1001-1412.2021.02.015 |
| 中文关键词: 晶质石墨矿 石墨片度 地球化学特征 矿床地质特征 矿床成因 纳钦圭阿 坦桑尼亚 |
| 英文关键词:crystalline graphite size of graphite crystal geochemical characteristics geological characteristics of deposit deposit genesis Nachingwea Tanzania |
| 基金项目:2018年度江苏省地质勘查专项（文号：苏财建〔2018〕96号）和2019年度江苏省省外、国外矿产资源风险勘查专项（文号：苏矿地发〔2019〕139号）联合资助。 |
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| 中文摘要: |
| 纳钦圭阿石墨成矿带位于坦桑尼亚南部林迪—姆特瓦拉地区，近年来发现一系列大型、超大型优质晶质石墨矿，尚未见系统报道。该成矿带东西宽约40 km，南北长约120 km，区域岩性为一套中高变质的片麻岩、片岩、石英岩、大理岩、角闪岩等，局部混合岩化强烈。地层呈NE—NEE向展布，局部平卧褶皱、鞘褶皱等发育，断裂构造以NE向为主，多顺层产出，NW向断层常错断石墨含矿地层。石墨矿体呈层状、似层状产出，发育多层矿体。矿体规模沿走向延伸从500 m~10 km，矿体群宽度100~500 m，单矿体厚度2~100 m。矿石类型以片岩型、片麻岩型为主，在石英岩、大理岩、伟晶岩中常见石墨矿化。围岩与夹石主要有片岩、片麻岩、大理岩、角闪岩等。原矿石墨片径多为0.10~2.40 mm，+100目含量大多大于95%，+50目含量大于67%，精矿石墨片径+100目含量为54%~75%，+50目含量为12%~49%。石墨矿石主量元素具有富铝硅贫钙的特征，根据地球化学原岩恢复图解投点，原岩为一套含碳、富铝的泥砂质沉积建造，可能混入少量火成岩。初步分析认为，纳钦圭阿成矿带晶质石墨矿床成因属于区域变质型矿床，成矿物质来源主要为原岩中的有机碳。 |
| 英文摘要: |
| The Nachingwea graphite ore belt is located in the Lindi-Mtwara region in the southern Tanzania. In recent years, a series of large and super-large high-quality crystal graphite deposits have been discovered. The belt is about 40 km wide from east to west and 120 km long from north to south. A set of mid-high grade metamorphic gneiss, schist, quartzite, marble, amphibolite, etc., are developed regionally with strong local migmatization. The strike of strata is NE-NEE and folds such as horizontal folds, sheath folds, and flow folds are developed regionally. Faults trending NE are dominant and developed along the bedding. The northwest trending faults often displaced graphite ore-bearing strata. Graphite ore bodies are layered and quasi-layered, 500 m to more than 10 km long, 100 m to 500 m wide, and 2 m to more than 100 m thick. The gneiss-hosted and schist-hosted ores are the main ore types and graphitization is occasionally seen in quartzite, marble, and pegmatite. The host rocks and horse stone mainly include schist, gneiss, marble, amphibolite, etc. Diameter of the graphite scale is between 0.100 mm to 2.40 mm, the scale of +100 mesh is mostly greater than 95%, and the +50 mesh is greater than 67%. The graphite concentrate is +100 mesh is 54% to 75%, +50 mesh is 12% to 49%. The graphite ore is characterized by rich aluminum, silicon and depletion of calcium. The reconstruction diagram shows that the original rock may be a set of carbon-rich and aluminum-rich muddy sandy sedimentary formation and a small amount of igneous materials may be incorporated. Genetically the crystalline graphite deposits in the Nachingwea belt are regional metamorphic deposits with ore material source mainly from organic carbon in the original rock. |
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