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本文通过岩相特征、粘土岩微量元素及生物标志物分布综合研究认为,民和盆地早中侏罗世由湖盆水下扇经水退为陆上河流冲积扇,后又水进演变为湖泊,直至水退消亡。粘土岩Sr/Ba介于0.11—0.23,B为25—75ppm,B/Ga为0.7—0.1,是淡水沉积环境的产物。中统窑街组第二段为沼泽相煤系地层,C_(27)甾烷10.6％—40.1％;第四段发育半深湖—深湖相油页岩、泥岩,富C_(27)甾烷35.2％—38.4％,并相对富Ga、V、Ti;第五段发育中—大型交错层理三角洲平原砂岩相,泥岩相对富Sr、K。
Based on the comprehensive analysis of the lithofacies characteristics, trace elements in clay rock and the distribution of biomarkers, it is considered that the Early Middle Jurassic of the Minhe Basin was subsided by the submarine fan of the lake basin to the alluvial fan of the onshore river and later evolved into a lake Until the water retreats. Claystone Sr / Ba ranged from 0.11 to 0.23, B from 25 to 75 ppm and B / Ga from 0.7 to 0.1 were the products of freshwater depositional environment. The second section of Zhongjieyaojie Formation is marsh facies coal seam, with C 27 sterane (10.6% -40.1%). In the fourth stage, semi-deep lacustrine-deep lake oil shale, mudstone, C 27 steroid Al and 35.2% -38.4% Al are abundant, and are relatively rich in Ga, V and Ti. In the fifth section, medium- and large-scale interlayered deltaic sandstone facies are relatively developed, and mudstone is relatively rich in Sr and K.