六盘水矿区龙潭组元素地球化学及古沉积环境特征

Longtan Formation Element Geochemical and Paleosedimentary Environment Features in Lupanshui Mining Area

根据六盘水矿区的地质背景、前人研究成果及区内汪家寨、大河边及月亮田煤矿采样测试资料的分析,运用地球化学指标指示沉积环境,对区内龙潭组泥岩元素地球化学及古沉积环境特征进行了研究,结果表明:区内亲石元素中Li、Be、Sc、Mo、Th、U、Ta、Zr,亲铜元素中Cu、Zn、Ga、Sb、Pb,亲铁元素中V、Cr、Co、Ni等相对富集,其中Li、Cu、Zr、V、Cr等元素丰度大于上地壳平均值;Rb、Mo、Cs、Ba等元素则有所亏损。区内样品的稀土分布模式整体特征均属于轻稀土元素相对富集、重稀土元素相对亏损型,且Eu元素微弱负异常,Ce元素无异常。研究区内龙潭组沉积主体时期以温湿气候,海陆过渡相沉积环境和还原性环境为主,有利于植物的大量繁殖和成煤作用,晚期短暂出现过干热气候且沉积环境转换为以海相为主。物源主要受峨眉山玄武岩期火山作用的影响,成岩母质以玄武岩为主,物源主要来自大陆岛弧和被动大陆边缘。

Based on geological setting, previous studied results in the Lupanshui mining area, and analyses of Wangjiazhai, Dahebian and Yueliangtian coalmines sampling and tested data in the area, through sedimentary environment geochemical indicators, studied Longtan Formation mudstone element geochemical and paleosedimentary environment features. The result has shown that the lithophile elements Li, Be, Sc, Mo, Th, U, Ta and Zr;chalcophile elements Cu, Zn, Ga, Sb and Pb;siderophile elements V, Cr, Co and Ni are relatively enriched. In which, element abundance of Li, Cu, Zr, V and Cr are larger than in the upper crust average;while Rb, Mo, Cs and Ba are deficit. Sample REE distribution pattern features on the whole belong to LREE relatively enriched and HREE deficit;Eu weak negative anomaly and Ce no anomaly. Study area Longtan Formation main sedimentary period was mainly in warm humid climate, paralic sedimentary environment and reducing environment, thus in favor of abundant plant propagation and coal forming process;later period had been transient arid, hot climate, and mainly marine sedimentary environment. Provenance had impacted by volcanism during the Emeishan stage, diagenetic parent material is basalt in continental island arc and passive continental margin.