鄂尔多斯盆地镇-泾地区中侏罗统延安组沉积体系及聚煤特征

Depositional systems and coal accumulation in the Middle Jurassic Yan'an Formation in the Zhenyuan-Jingchuan region,Ordos Basin

在前人研究的基础上,结合大量新的钻井、测井资料,以鄂尔多斯盆地镇原-泾川地区中侏罗统延安组为例,运用沉积学的方法详细阐述了研究区目的层位的沉积体系,以及重点沉积微相的发育特征。延安组自下而上由河流沉积体系逐渐过渡为三角洲沉积体系。沉积微相主要发育有河流体系的心滩、边滩、河漫滩和岸后沼泽,以及三角洲体系的分流河道、洪泛平原和平原沼泽等。另对研究区延安组的聚煤特征给予了分析,并从构造、环境、气候及古地形等方面讨论了该区的成煤控制因素。

The depositional systems and sedimentary microfacies are dealt with on the basis of new borehole and well-log data on the target strata in the Middle Jurassic Yan＇an Formation in the Zhenyuan-Jingchuan region, Ordos Basin. There are gradations from the fluvial depositional system to the delta depositional system from the base upwards in the Yah＇an Formation. The sedimentary microfacies consist of the channel bar, point bar, overbank and backswamp microfacies in the fluvial depositional system, and distributary channel, flood plain and swamp microfacies in the delta depositional system. The coal accumulation and controlling factors are also discussed in the light of tectonics, environments, palaeoclimates and landforms in the Yan＇an Formation.