鄂尔多斯盆地是我国西北中生代规模最大的内陆盆地之一,蕴藏着丰富的能源资源.本文利用沉积构成单元分析的新思维对延安地区延安组岩石成因标志和宏观沉积特征进行了详实的研究,准确地恢复了形成延安组的古地理环境.解释了该区无聚煤作用的环境决定因素.延安组主要由灰色砂岩、泥岩、碳质泥岩及少量煤线组成.研究表明鄂尔多斯盆地延安地区延安组属稳定大地构造条件下的河流-浅湖三角洲沉积.该区河流-湖泊三角洲沉积.其沉积构成单元有河道沉积、床质砂体、河道前积沉积、侧向加积、席状砂沉积、越岸沉积、前缘沉积.湖缘席状砂沉积、浅湖-前三角洲和湖泥沉积.沉积特征具有以下特点:河道改道速度非常快,决口事件频繁发生;前三角洲非常薄;三角洲剖面绝大部分由三角洲前缘和三角州平原组成;河口坝沉积由砂岩泥岩互层组成;水下分流河道异常发育,规模可大可小;在废弃的三角洲平原中,由于经常受河流改道的影响,不能形成长期稳定的沼泽环境,因此无厚煤层形成. The Ordos Basin is one of the largest inland basins in the Mesozoic in northwestern China and contains a wealth of energy resources.In this paper, we use the new thinking of sedimentary unit analysis to make a detailed study of the rock genetic signatures and macro-sedimentary features of the Yan’an Formation in Yan’an, The paleogeographic environment that formed the Yan’an Formation was restored and the environmental determinant of coal accumulation without coal was explained.The Yan’an Formation is mainly composed of gray sandstone, mudstone, carbonaceous mudstone and a few coal lines.The study shows that the Yan’an Formation in Yanan area of ​​Ordos Basin Sedimentary facies of rivers and shallow lakes under stable geotectonic conditions are characterized by river-lake delta deposits, sedimentary units with river sediments, bedrock sand bodies, pre-river sediments, lateral accretion, sheet sand deposits, Sedimentation of the lakeside sediments, shallow lake-front delta and lacustrine sediments. The sedimentary characteristics have the following characteristics: the river diversion speed is very fast, the frequent occurrence of ripple occurs; the former delta is very thin; the delta profile Most of which consists of the delta front and the delta plains; estuary dam sediments are interbedded with sandstone and mudstone; underwater distributary Abnormal development of the road, the size may be larger or smaller; in the abandoned delta plain, due to river diversions often affected, can not form a long-term stable swamp environment, so no thick seam formation.