鄂尔多斯盆地西南地区延长组长7段细粒沉积物特征研究

发布时间：2018-03-20 03:08

  本文选题：细粒沉积　切入点：有机质类型　出处：《地质学报》2017年05期 　论文类型：期刊论文

【摘要】：鄂尔多斯盆地西南地区广泛发育细粒沉积物。在大量钻井、测井资料的基础上,通过岩芯分析、地球化学测试等方法,从湖泊演化过程中水体盐度、氧化还原条件、生产力变化及地化特征等方面研究细粒沉积物特征与分布规律,进而分析细粒沉积物主控因素。结果表明:鄂尔多斯盆地西南地区延长组长7沉积期,气候温暖潮湿,半深湖—深湖大面积分布,富有机质细粒沉积物发育。该期形成的富有机质页岩主要受湖盆底形、砂体沉积模式的影响。尤其在长73沉积期,快速湖侵,湖水深度和范围急剧增加,古生产力高,湖泊表层水体与底层水体存在盐度分层,形成大面积缺氧环境,有利于富有机质页岩大规模发育与保存,在深湖区平缓地带,陆源碎屑供给不足,有机碳含量高,有机质类型好,以Ⅰ、Ⅱ型为主,斜坡带半深湖区,陆源碎屑影响明显,粉砂质泥岩发育,干酪根以Ⅱ型为主,局部地区发育Ⅲ型干酪根。
[Abstract]:Fine grain sediments are widely developed in the southwest of Ordos Basin. On the basis of a large amount of drilling and logging data, through core analysis and geochemical testing, the salinity and redox conditions of the water body during the evolution of the lake are studied. The characteristics and distribution of fine-grained sediments are studied in terms of productivity changes and geochemistry characteristics, and the main controlling factors of fine-grained sediments are analyzed. The results show that Yanchang Group 7 sedimentary period, warm and humid climate in southwest Ordos Basin, and so on. The organic matter rich shale formed in this period was mainly influenced by the lacustrine basin bottom and the sedimentary model of sand body, especially during the Chang73 sedimentary period, the rapid lacustrine transgression. The depth and range of lake water increased sharply, the paleoproductivity was high, the surface water and bottom water of the lake were stratified by salinity and formed a large area of anoxic environment, which was conducive to the large-scale development and preservation of organic matter rich shale, and in the gentle zone of deep lake region. The continental clastic supply is insufficient, the organic carbon content is high, the organic matter type is good, mainly type 鈪，

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