鄂尔多斯盆地南部烃源岩沉积环境研究

目的探讨鄂尔多斯盆地南部烃源岩沉积环境与地球化学特征的关系。方法以井下剖面烃源岩的地球化学分析资料为主，依据有机碳含量分布、有机质类型及饱和烃气相色谱等特征对烃源岩的沉积环境进行了研究，分析了沉积环境对有机质丰度和类型的影响因素，探讨了鄂尔多斯盆地南部烃源岩沉积水体的主量元素、古气候及古盐度条件。结果鄂尔多斯盆地南部烃源岩层系沉积时气候潮湿，沉积水体的古盐度较淡；半深湖-深湖相带沉积的还原程度强、有机质能被及时埋藏的灰黑色泥岩,大多有机质丰度高、有机质类型好；河流-沼泽相带沉积的灰色-绿灰色泥岩类烃源岩有机质丰度较低、有机质类型偏差。结论还原程度强、具一定深度水体的沉积相带是原始有机质沉积的良好场所，有机质能及时沉积、保存下来，烃源岩有机质丰度大多高；气候条件相对干燥、大气降水少、陆源碎屑物补充不足或较长时间处于氧化程度较高条件下沉积的碳酸盐岩类岩石．有机质丰度明显偏低。

Reseach on the diposite environments about source rocks in south Ordos Basin

Aim To probe the relationship between the environment and source rocks geochemistry characteristics in south Orduos Basin. Methods Combined mainly geochemical data of the source rocks with diffrent bore specimens, the sedimentary environments about the source rocks are studied in abundance and types of the organic metters as well as saturated hydrocarbon chromatogram parameters in the source rocks. And the influence factors are analysised finaly in south Ordos Basin. The major elements and palaeclimate as well as palaeosalinity are researched. Results The studies demonstrated that the palaeclimate was moister relatively and palaeosalinity was lighter. It is considered that the zones deposited in half deep lake to deep lake where the organic matters could have been buried and preserved contemporarily in strong reducing environment, there are more abundance of organic metters in the source rocks such as black grey mudsource. In the zones deposited in the river to delta there are less abundance and the worse types in the source rocks like green grey mudstone. Conclusion Among the source rocks, there is less abundance in the carbonate source rocks that deposited under the more oxide condition, in which terrienous clastic deposits were inadequate during longer time and the palaeclimate was drier relatively. The more reducing and favorable sedimentary zones are better place, there are higher abundance of organic metters in the source rocks with strong reducing environment,where the organic matters can be buried and preserved contemporaryly, and the source rocks are generally high in organic content, and vice versa.