鄂尔多斯盆地侏罗纪含煤岩系不限于延安组，其始于富县组沉积末期(Toarcian晚期)，终于直罗组沉积早中期(Bathonian期)。关注侏罗纪含煤岩系衰退演化阶段的直罗组聚煤特征与发育演化规律研究，不仅有助于阐明鄂尔多斯盆地侏罗纪含煤岩系的地层结构，重塑Bathonian期古气候变化和迁移的细节过程，还有助于从外部还原介质的角度剖析砂岩型铀矿的成矿环境。结合区域露头调查并通过大范围钻孔资料的地层对比发现，在直罗组下段下亚段沉积时期，全盆地具有较大范围的聚煤作用，聚煤区围绕盆地沉降中心呈环带状展布,说明此时的古气候尚处于潮湿环境。但是，聚煤规模却远不如延安组，以发育薄煤层、煤线和碳质泥岩为特征，说明Bathonian期鄂尔多斯盆地总体处于由潮湿向干旱转变的古气候背景中。调查发现，从直罗组下段上亚段沉积期开始，全盆地聚煤作用步调不尽一致。此阶段，盆地南部、中部和东部聚煤作用终结，预示古气候已转变为干旱型。而在盆地北部和西部，聚煤作用持续发育，自东向西聚煤层位逐渐抬升，目前见到最高的聚煤层位位于贺兰山二道岭地区的直罗组中上段，煤层最厚可达6.60 m。这预示着，始于Toarcian晚期开始形成的潮湿古气候经由Aalenian-Bajocian期和Bathonian期的演化，最终从贺兰山二道岭地区退出而被干旱古气候所取代，古气候迁移的途径为南东—北西向。近10 a来，鄂尔多斯盆地北部的“煤铀兼探”实践证实，直罗组微弱的聚煤作用是砂岩型铀矿形成的关键制约因素(外部还原介质)。它不仅在一定程度上限定了砂岩型铀矿的成矿层位，而且直接参与到了铀成矿的全过程之中。直罗组微弱聚煤作用的产物——煤层或碳质泥岩被认为是东胜铀矿田的重要找矿标志之一。

The Jurassic coal measures in Ordos Basin are not limited to Yan’an Formation,the coal accumulation lasted from the end of Fuxian Formation (late Toarchian) to the early and middle Zhiluo Formation (Bathonian stage).The study on the coal accumulation characteristics and evolution law of Zhiluo Formation in the decline and evolution stage of Jurassic coal measures is helpful not only to clarify the stratigraphic structure of Jurassic coal measures in Ordos Basin,but also to reshape the detailed process of paleoclimate change and migration in the Bathonian period,and to analyze the metallogenic environment of sandstone type uranium deposits from the perspective of external reduction medium.Combined with the regional outcrop survey and stratigraphic correlation of large scale borehole data,it is found that the whole basin has a large range of coal accumulation during the sedimentary period of the lower sub member of lower member of Zhiluo Formation,and the coal accumulation area is distributed as a ring belt around the subsidence center of the basin,indicating that the paleoclimate at this time was still in a humid environment.However,the scale of coal accumulation is far less than that of Yan’an Formation.It is characterized by the development of thin coal seams,coal lines and carbonaceous mudstones,which indicates that the Ordos Basin in the Bathonian period was in the paleoclimatic background of transition from humid to arid.It is found that from the upper sub member of the Zhiluo Formation,the coal accumulation in whole basin is not consistent.During this period,the coal accumulation in the southern,central and eastern parts of the basin ended,indicating that the paleoclimate had changed into arid.However,in the north and west of the basin,the coal accumulation continues to develop,and the coal accumulation position gradually rises from east to west.At present,the highest coal accumulation position is found in the middle and upper sub members of the Zhiluo Formation in Erdaoling area of Helan Mountain,and the thickest coal seam can reach 6.60 m.This indicates that the humid paleoclimate,which began to form in the late Toarcian period,evolved through Aalenian Bajocian and Bathonian periods,and finally exited from Erdaoling area of Helan Mountain and was replaced by arid paleoclimate.The migration path of paleoclimate is from southeast to northwest.In recent 10 years,the practice of “coal and uranium exploration” in northern Ordos Basin has confirmed that the weak coal accumulation in Zhiluo Formation is the key factor (external reducing medium) for sandstone type uranium deposit formation.It not only limits the metallogenic horizon of sandstone-type uranium deposits to a certain extent,but also directly participates in the whole process of uranium mineralization.The Coal seam or carbonaceous mudstone,the product of weak coal accumulation in Zhiluo Formation,is considered as one of the important prospecting indicators in Dongsheng uranium ore field.

1 侏罗纪含煤岩系基本结构

2 盆地东北部直罗组聚煤规律

3 直罗组聚煤作用的大区域追踪对比

   3.1 鄂尔多斯盆地西部

   3.2 鄂尔多斯盆地南部

   3.3 鄂尔多斯盆地中东部

   3.4 贺兰山以及巴彦浩特盆地

4 泛鄂尔多斯盆地直罗组聚煤规律

5 直罗组聚煤作用的地质意义

   5.1 古气候变迁的指示意义

   5.2 砂岩型铀矿的成矿环境意义

6 结论