摘要
为厘清贵州上二叠统龙潭组煤系地层的物源,以黔西南地区黔普地1井为研究对象,采集了上二叠统龙潭组的岩心进行稀土元素分析。结果表明,龙潭组的稀土总量较高(177.03×10~(-6)~592.58×10~(-6)),轻、重稀土分馏明显,稀土元素配分模式呈轻稀土富集、重稀土相对亏损的右倾型;(La/Sm)_N为2.63~4.72,(Gd/Yb)_N值为1.47~2.218,表明轻稀土分馏较重稀土严重;δEu无异常。研究表明,其形成的构造环境与大陆边缘与大陆弧相近,推测黔普地1井二叠系龙潭组物质来源以玄武岩为主。
In order to clarify the provenance of the Upper Permian Longtan Formation which is the coal measure stratum in Guizhou Province,we have collected rocks of the Longtan Formation from cores of the Qianpudi Well-1 for analyzing their rare earth elements(REE).The results show that rocks of the Longtan Formation contain relatively high contents of total rare earths elements,varying from 177.03×10~(-6)to 592.58×10~(-6),with the average∑REE content of 381.84×10~(-6).Their REE distribution patterns are right declined ones with relative LREE-enrichment,HREE-depletion,obvious fractionationbetween LREE and HREE,and no Eu anomaly.The ratios of(La/Sm)_Nand(Gd/Yb)_Nvary from 2.63 to 4.72 and from1.47 to 2.218,respectively,indicating that the fractionation of LREE is stronger than that of the HREE.This research shows that the diagenetic tectonic environment of the Longtan Formation is similar to those of the continental margin and continental arc.It is further speculated that the materials of the Upper Permian Longtan Formation in the Qianpudi Well-1could be mainly sourced from the Emeishan basalt.
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