ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    南秦岭构造带金伯利岩类成因及其含矿性研究

    Geochemistry and Metallogenic Characteristics of Ultramafic Volcanic Rocks in Southern Qinling Tectonic Belt

    • 摘要: 本次研究综合野外地质、岩相学、矿相学和地球化学等多学科方法,对南秦岭造山带内的超基性火山岩开展研究,以期为该地区超基性火山岩的地球化学及其与含矿性特征提供约束,研究成果对南秦岭造山带寻找金刚石原生矿具有重要意义。研究结果显示,南秦岭岚皋地区超基性岩野外多呈不规则管状、筒状、透镜状,主要岩石类型为蚀变金伯利角砾岩和含砾凝灰状金伯利岩等。样品SiO2含量平均值为40.36%,MgO含量平均值为11.09%,CaO含量平均值为9.7%,TFe2O3含量平均值为13.63%,Al2O3含量平均值为9.67%,TiO2含量平均值为3.84%,CaO/Al2O3比值平均为1.00,CaO/TiO2比值平均为2.69。明显亏损K、Ba、Sr等元素,富集高场强元素U、Nb、Zr、Sm,Nb/U比值平均为37.59。稀土元素总量(∑REE)平均值为271.833×10-6;轻、重稀土(LREE)含量平均值为分别为248.602×10-6、23.231×10-6;轻重稀土元素比值(LREE/HREE)平均为10.61。本次研究对样品利用碱性组分和超基性组分共同约束其含矿性,样品在图解中显示成矿效果不佳,经验判别式也指示金伯利岩属于贫矿类型。建议从构造解析、矿物学等角度对其含矿性进行进一步研究。

       

      Abstract: This study integrates multi-disciplinary methods such as field geology, petrography, mineralogy and geochemistry to investigate the ultrabasic volcanic rocks within the Southern Qinling Orogenic belt. The aim is to provide constraints for the geochemistry of the ultrabasic volcanic rocks in this area and their ore-bearing characteristics. The research results are of great significance for the search of primary diamond deposits in the Southern Qinling orogenic belt. The research results show that the ultrabasic rocks in the Langao area of the Southern Qinling Mountains are mostly irregular tubular, cylindrical and lens-shaped in the wild. The main rock types are altered Kimberly breccia and gravelly tuxaceous kimberly, etc. The average content of SiO2 in the samples was 40.36%, that of MgO was 11.09%, that of CaO was 9.7%, that of TFe2O3 was 13.63%, that of Al3O2 was 9.67%, and that of TiO2 was 3.84%. The average ratio of CaO/Al2O3 is 1.00, and the average ratio of CaO/TiO2 is 2.69. Overall, it is enriched with large-ion lithophilic elements and light rare earth elements, significantly deficient in elements such as K, Ba, and Sr, and enriched with high-field elements such as U, Nb, Zr, and Sm. The average Nb/U ratio is 37.59. The average total amount of rare earth elements (∑REE) is 271.833×10-6. The average contents of light and heavy rare earths (LREE) were 248.602×10-6 and 23.231×10-6 respectively. The average ratio of light and heavy rare earth elements (LREE/HREE) is 10.61. In this study, both basic and ultrabasic components were used to jointly constrain the ore-bearing properties of the samples. The diagrams of the samples show that the mineralization effect is not good, and the empirical discriminant also indicates that kimberlite belongs to the poor ore type. It is suggested that further research be conducted on its ore-bearing property from other perspectives such as structural analysis and mineralogy.

       

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