| 山西省大同市新荣区石墨矿岩石矿物地球化学特征与成因 |
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| 引用本文：梁钰琦,赵永,吴光存,张越,夏庆霖.2020.山西省大同市新荣区石墨矿岩石矿物地球化学特征与成因[J].地球学报,41(6):827-834. |
| DOI：10.3975/cagsb.2020.071903 |
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| 基金项目:山西省矿业权价款地质勘查项目“山西省大同市新荣区七里村-碓臼沟石墨矿详查项目”(编号: SXZDF20170820);“山西省大同市新荣区白山村石墨矿详查项目”(编号: HXCT01-2018F005) |
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| 中文摘要:山西省大同市新荣区石墨矿带总体呈北东—南西向展布, 长约22 km, 赋矿层位为中下太古界右所堡组, 岩性为含石墨黑云斜长片麻岩。目前该矿带上已有7个勘查区, 累计查明晶质石墨矿物资源量约 5000万吨, 但对其矿床成因类型研究相对较少。本文收集整理和分析总结了区域内地质资料及化验分析结果, 采用变质岩原岩恢复的四种方法确定该矿带的成因: 从石墨矿带的矿体产状和岩石组合、岩相学和矿物学特征定性判断该矿带矿床为沉积岩区域深变质成矿类型; 矿体样品地球化学微量元素比值(Sr:Ba等)符合副变质岩特征; 稀土元素配分曲线及其研究表明矿体及围岩具有沉积岩变质特征; 以TiO2-F图解、[(al+fm)–(c+alk)]/Si图解以及(al-alk):c图解展示的岩石化学特征半定量地确认新荣区石墨矿带矿床为以黏土岩为主的区域变质成矿。新荣区石墨矿带成因类型的确定填补了该区域矿床成因类型研究的空白, 为下一步地质找矿及建模提供了重要依据; 三种图解相结合, 逐步缩小原岩范围, 锁定原岩类型, 为变质岩原岩恢复及矿床成因研究提供了新的思路和判别方法。 |
| 中文关键词:大同市新荣区 晶质石墨 原岩恢复 稀土元素 元素比值 尼格里值 成因类型 |
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| Research on Geochemistry Characteristics and Genesis of the Graphite Deposit in Xinrong District of Datong City, Shanxi Province |
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| Abstract:The NE-SW trending graphite belt (graphite-bearing oblique gneiss) extends for more than 22 km in Xinrong District of Datong City. Although 50 million tons of scaly graphite mineral resources were prospected along the ore belt, the study of the genetic type of the deposit in this area is relatively insufficient. Based on local geological information and analytical results, the authors determined the genesis of the deposit by restoring the original of metamorphic rock in this paper. The belt was deeply metamorphosed from sedimentary rock as shown by qualitative judgment from the geological attitudes and combination, petrographic signs, and secondary mineral characteristics. The element ratio (Sr:Ba, etc.) and rare-earth element curves show that the ore and its surrounding rocks experienced metamorphism from sedimentary rock. Combined with TiO2-F diagram, [(al+fm)–(c+alk)]/Si diagram and (al–alk):c in the petrochemical characteristics, the authors gradually determined the range of the original rock, and finally detected that the clay rocks were dominantly the original rocks in Xinrong District. It is concluded that the genetic type of the graphite ore belt in Xinrong District is a region of deep metamorphism of clay rocks, and this finding fills the gap of the study of the genesis type of the deposit in this region and provides the basis for further prospecting and geological modeling. |
| keywords:Xinrong District of Datong City scaly graphite protolith recovery rare-earth element element ratio Negri value genetic type |
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