鄂尔多斯盆地中部上三叠统瓦窑堡组层序——古地理与聚煤规律  

Sequence-palaeogeography and coal accumulation of the upper Triassic Wayaobu Formation in central Ordos Basin

作　　者：李明培 邵龙义[3] 夏玉成[1] 李智学 贺丹 李丽[3] Li Ming-Pei;Shao Long-Yi;Xia Yu-Cheng;Li Zhi-Xue;He Dan;Li Li(School of Geology and Environment,Xi'an University of Science and Technology,Xi'an 710054,China;Innovation Technology Research Institute of Shaanxi Investment Group Co.,Ltd.,Xi'an 710061,China;School of Geoscience and Surveying Engineering,China University of Mining&Technology(Beijing),Beijing 100083,China;Shaanxi Investment Group Co.,Ltd.,Xi'an 710061,China;Shaanxi Coal Geology Group Co.,Ltd.,Xi'an 710026,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]陕西投资集团创新技术研究院有限公司,陕西西安710061 [3]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [4]陕西投资集团有限公司,陕西西安710061 [5]陕西省煤田地质集团有限公司,陕西西安710026

出　　处：《古地理学报》2021年第2期375-388,共14页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:41572090);中国矿业大学(北京)越崎学者A类项目联合资助。

摘　　要：为研究鄂尔多斯盆地中部上三叠统瓦窑堡组层序地层格架下的沉积演化与聚煤规律,利用野外露头、钻孔以及测井资料,识别出瓦窑堡组共发育5种岩石类型及17种岩相类型。以区域不整合面、地层颜色突变面和河道下切谷冲刷面等层序地层界面,将瓦窑堡组划分为3个三级层序SQ1、SQ2和SQ3,确定了每个层序的沉积范围、岩相组合及沉积体系。采用单因素作图法,综合考虑沉积相等多因素确定沉积单元边界,恢复了三级层序的沉积格局。瓦窑堡期沉积单元主要为曲流河、冲积平原沉积、三角洲平原、三角洲前缘和湖泊,自SQ1期至SQ3期,冲积平原、三角洲沉积逐步向湖域推进,滨—浅湖范围逐渐萎缩。三角洲平原的发育为聚煤作用提供了有利场所,形成了具有一定工业价值的煤层。从SQ1期到SQ3期,聚煤作用主要发生于湖侵体系域,且随着聚煤作用逐渐增强,泥炭堆积速率与可容空间增加速率逐渐达到平衡,煤层总厚度和单层煤层最大厚度逐渐增大。该研究成果可为鄂尔多斯盆地上三叠统瓦窑堡组煤炭资源潜力预测和富油煤形成机理研究提供地质依据。In order to study the evolution of the sequence and paleogeography and the coal accumulation law of the upper Triassic Wayaobu Formation in the central Ordos Basin,the field outcrops,boreholes and logging data are used to identify five types of lithology and 17 types of lithofacies in the Wayaobu Formation.Based on the sequence stratigraphic interfaces such as regional unconformity surface,the abrupt change of formation surface and the erosion surface by the incised river valley,the Wayaobu Formation is divided into three third-level sequences,i.e.,SQ1,SQ2 and SQ3.The sedimentary range,lithofacies assemblages and sedimentary system of them are identified.It shows that the sedimentary units of SQ1,SQ2 and SQ3 in the Wayaobu stage are mainly composed of meandering river,alluvial plain,delta plain,delta front and lake.From the SQ1 period to the SQ3 period,the alluvial plain and delta gradually advanced to the lake area,while the area of lake gradually shrinked.The development of delta plain provided a favorable place for coal accumulation and the coal seam of industrial importance formed.Between the SQ1 period and the SQ3 period,the coal accumulation mainly occurred in the lacustrine transgressive system tract.With the gradually development of coal accumulation,the rate of peat accumulation and the growth rate of accommodation space gradually reached a balance,and the total thickness of coal seam and the maximum single layer thickness of coal seam gradually increased too.The results can provide geological basis for coal resource potential prediction and formation mechanism research of oil-rich coal in the upper Triassic Wayaobu Formation of Ordos Basin.

关 键 词：层序地层 岩相古地理 聚煤特征 瓦窑堡组 延长群 鄂尔多斯盆地 

分 类 号：P531[天文地球—古生物学与地层学]