鄂尔多斯盆地泾川地区三叠系延长组烃源岩特征及其沉积环境

泾川地区位于鄂尔多斯盆地西南缘，烃源岩发育情况尚不明确。通过野外地质调查和钻井岩心观察，结合烃源岩测试及元素地球化学资料，对长10—长7烃源岩进行评价，在环境分析的基础上研究影响烃源岩发育的主要因素。结果表明：研究区延长组烃源岩以长7₃泥页岩为最好，有机质类型以Ⅰ型和Ⅱ₁为主，TOC为 0.42%～29%；长10—长7泥岩有机质以Ⅱ₂型为主，平均TOC含量低于 2%；Ro为 0.47%～1.08%，有机质基本已成熟。长10—长7烃源岩形成于温暖潮湿的环境，弱还原弱氧化的淡水介质条件，水深相对较浅。古生产力、沉积速率及水介质环境影响烃源岩发育。热水活动促进了古生物的繁盛，P、Cu含量及 P/Ti值越高，有机质 TOC含量越高。（La/Yb）_N值越高，沉积速率越低，有机质越富集。Cu/Zn值越高，V/Cr值越高，Th/U值越低，水体还原性越好，有机质丰度越高。总之，热水活动提高了古生产力水平，相对较低的沉积速率有利于有机质的富集，还原性较强的水介质条件可使有机质得到良好的保存。陇县一带烃源岩因受陆源植物输入的影响，且形成环境不利，烃源岩品质相对较差。

Characteristics and sedimentary environment of the hydrocarbon source rock of the Triassic Yanchang Formation in Jingchuan area,Ordos Basin

It is not clear for the development of the hydrocarbon source rock in Jingchuan area of thesouthwest edge of Ordos Basin. Based on geological survey, core observation, hydrocarbonsource rock and element data, the characteristics and the main factors affecting the development of source rock were studied. The results show that： It is the best hydrocarbon source rock for shale of the Chang7₃ member of the Yanchang Formation in the study area. Thetype of organic matter is mainly Ⅰ and Ⅱ₁, and TOC is 0.42%～29%; The type of organicmatter of the mudstone in Chang10-Chang7 member is mainly Ⅱ₂, and the average TOC content is less than 2%; Ro is 0.47%～1.08%, and organic matter is basically mature. Thehydrocarbon source rocks of Chang10-Chang7 formed in warm and humid environment, withweak anoxia in fresh water environment and relatively shallow water depth. The development ofsource rocks was influenced by paleoproductivity, sedimentation rate and water environment.The hydrothermal activity promoted paleoproductivity. The hydrocarbon source rocks with higher P, Cu content and P/Ti value, have the higher TOC content of organic matter. The lowerthe deposition rate（higher（La/Yb）Nvalue）, the more enriched the organic matter of thehydrocarbon source rocks. Anoxic water condition（with higher Cu/Zn, V/Cr value and lower Th/U value）was beneficial to organic matter abundance. The hydrothermal activity increasedthe level of paleoproductivity, and the relatively low deposition rate was good for theenrichment of organic matter. The organic matter can be well preserved under the condition ofstrong anoxia water environment. The quality of the source rocks is relatively poor in Longxianarea because of the influence of the input of terrestrial plants and the unfavorable environment.