【摘要】 准噶尔盆地晚二叠世沉积的芦草沟组湖相页岩是一套重要的烃源岩或油页岩资源。本文通过XRF和ICP-MS技术测试了该盆地东南缘博格达山地区芦草沟组油页岩的元素含量,分析了其分布与组成特征,阐述该区芦草沟组沉积时期的古环境特征。研究表明,芦草沟组油页岩样品大多数主元素含量偏低,但磷(P)含量较高, P/Ti比值为0.23～1.94;微量元素Sr/Ba比值多小于1, Sr/Cu比值处于4.88～12.36之间, V/Cr比值为2.40～3.91, V/(V+Ni)比值为0.70～0.83,古气候指数为0.48～0.61;轻重稀土元素比值为5.92～7.10,轻稀土元素明显富集。综合各参数特征及变化趋势表明,研究区芦草沟组沉积时期主要是半干旱-半湿润的古气候特征,总体上为半咸水的湖盆环境,沉积水体较深,沉积速率较慢,具有中-高的初始古生产力。从沉积初期至晚期,古气候逐渐变干旱,沉积水体盐度逐渐升高和还原性逐渐增大。研究区芦草沟组有机质富集属于生产力模式,主要受古气候和古生产力控制,但沉积后期沉积水体水化学条件的变化也为有机质保存提供了有利的条件。更多还原

【Abstract】 The late Permian Lucaogou Formation is a suite of oil shale in the southeastern Junggar Basin. Based on the XRF and ICP-MS analyses of oil shale samples, this study investigated their geochemical characteristics, including elemental features, changes in element content, and some elemental ratios to speculate on the ancient environmental characteristics during their sedimentary period and reconstruct the sedimentary environmental history. The results show that the content of most major elements is low in the Lucaogou Formation oil shale samples, but P is significantly enriched, with a P/Ti ratio value ranging from 0.23 to 1.94. For trace elements, most of the Sr/Ba ratios are less than 1, and the Sr/Ba ratio ranges from 4.88 to 12.36. Meanwhile, the V/Cr ratio varies from 2.40 to 3.91, and the V/(V+Ni) ratio is within the range of from 0.70 to 0.83. The paleoclimatic index is within a range of from 0.48 to 0.61. The investigated samples have a very high abundance of REEs, with the LREE/HREE ratio ranging from 5.92 to 7.10. The results show that the Lucaogou Formation mainly formed in a semi-arid and semi-humid climate, with a sedimentary environment of deep lacustrine facies under an anoxiccondition. The paleoproductivity proxies reflect a middle to high initial paleoproductivity. From the early to the late depositional stage, the paleoclimate changed from semi-humid to arid. Meanwhile, the water reducibility and the value of paleosalinity increased. The formation of organic matter in the Lucaogou Formation shale was predominantly controlled by paleoproductivity and paleoclimate. Additionally, the changes in water chemistry conditions during the late sedimentary period also provided a favorable environment for organic preservation.更多还原