准噶尔盆地吉木萨尔地区二叠系芦草沟组油页岩地球化学特征与成矿条件

【研究目的】本文旨在通过对比准噶尔盆地吉木萨尔地区二叠系芦草沟组高品位和低品位油页岩的品质和成因差异，揭示高品位油页岩的特殊成矿条件。【研究方法】对吉木萨尔地区两个剖面采集的露头样品，进行TOC、热解、含油率、微量、稀土元素测试，从而开展高品位和低品位油页岩有机地球化学特征，微量稀土元素特征及成矿条件差异分析。【研究结果】研究区高品位油页岩有机质类型为I型；低品位油页岩有机质类型为I-II1型。高品位和低品位油页岩中B、Ba、Cr、Nb、Sr、V、Zr等微量元素含量差异明显，高品位油页岩中各稀土元素平均含量和各样品稀土元素分布区间都小于低品位油页岩，且外源元素富集程度也相对更低，显示了更少的陆源碎屑输入。微量元素比值显示，研究区油页岩形成于温暖湿润气候，淡水—半咸水，还原环境。高品位油页岩与低品位油页岩相比，形成时水体盐度值更大，有机质生产力更高。【结论】温暖湿润气候背景下，相对较少的陆源碎屑供给，减少了对有机质的稀释和氧化破坏，同时较高的水体盐度值更利于水体分层，从而形成一个长时间的还原环境，再加上更高的有机质生产力，从而形成了高品位油页岩。

The geochemical characteristics and metallogenic condition of Permain Lucaogou Formation oil shale in Jimusaer, Junggar Basin, Xinjiang

This paper is the result of oil and gas exploration engineering.Objective]This paper aims to reveal the special metallogenic conditions of high-grade oil shale by comparing the quality and genetic differences between high grade and low grade oil shale of Permian Lucaogou Formation in Jimusaer area, Junggar Basin. Methods]TOC, Rock-eval, oil yield, trace and rare earth elements were tested on outcrop samples collected from two sections in Jimusar area, so as to analysis the difference of organic geochemical characteristics, trace and rare earth element characteristics and metallogenic conditions of high-grade and low-grade oil shale. Results]Research results show that, the organic matter type of high grade oil shale is type I, but the organic matter type of low grade oil shale is type I-II₁. The trace elements contents of the high grade oil shale (such as B, Ba, Cr, Nb, Sr, V, Zr) are significantly different from that of low grade oil shale. The average contents of rare earth elements and the distribution range of rare earth elements in high grade oil shale are smaller than that in low grade oil shale. And elements that are usually enriched in terrestrial detrital minerals of the high grade oil shale is lower than that of low grade oil shale, which shows less terrigenous clastic input of high grade oil shale. The trace elements ratio shows that the oil shale in the study area is formed in warm and humid climate, semi-salty water and reducing environment. Compared to the low grade oil shale, the high grade oil shale was formed with higher salinity water and higher organic matter productivity. Conclusions] Under the background of warm and humid climate, the relatively small supply of terrigenous clastics reduces the dilution and oxidation of organic matters, and high salinity is more conducive to water stratification, thus forming a long-term reduction environment. Combined with higher organic matter productivity, high-grade oil shale is formed.Highlights: The oil shale in Jimusaer is formed in warm and humid climate, semi- salty water and reducing environment. The relatively small supply of terrigenous clastics, and high salinity is more conducive to water stratification, combined with higher organic matter productivity, high-quality oil shale is formed.