摘要： 下二叠统太原组灰岩在鄂尔多斯盆地中东部广泛分布,已有多口井试气后相继获得了工业气流,勘探潜力较大,但目前对该组灰岩沉积微相类型与沉积模式的研究尚不够成熟。基于对鄂尔多斯盆地中东部下二叠统太原组大量钻井岩心、薄片的详细描述,综合测井资料,从岩石类型、沉积相类型、典型沉积序列、沉积模式等方面,深入分析了盆地中东部太原组灰岩的沉积特征与沉积过程。结果表明: 鄂尔多斯盆地中东部太原组由海相碳酸盐岩、混积岩及陆源碎屑岩3大类15小类岩石类型构成,其中海相碳酸盐台地相可进一步划分为生屑滩、滩间海、潮上带(泥坪)、潮间带(泥灰坪)等7种沉积微相。依据地层剖面精细刻画, 共识别出海陆过渡环境下的6个典型序列,其中序列1、2、3为海相碳酸盐岩沉积序列,序列4、5、6为陆相三角洲沉积序列。综合分析认为,鄂尔多斯盆地中东部早二叠世太原组沉积时期经历了由陆相三角洲(碎屑沉积)→海陆过渡相(混积沉积)→海相碳酸盐台地(碳酸盐沉积)的沉积演化,受沉积期地貌影响,整体具有“北砂南灰,上覆泥煤”的沉积充填模式。研究成果不仅丰富了对鄂尔多斯盆地中东部太原组的沉积地质认识,也为后续太原组天然气勘探提供了重要的理论依据。

关键词: 鄂尔多斯盆地, 下二叠统, 灰岩, 沉积特征, 沉积模式

Abstract: The Taiyuan Formation limestone is extensively distributed in the central and eastern parts of the Ordos Basin,with successful gas flow tests conducted in several wells. It has significant exploration potential and has gained increasingly attention in recent years. However,research on the sedimentary microfacies types and sedimentary modes of Taiyuan Formation limestone in the central and eastern parts of the basin remains undeveloped. Based on a detailed analysis of numerous drilling cores,thin sections,and well logging data from the Taiyuan Formation limestone in the central and eastern parts of the basin,the sedimentary characteristics and sedimentary processes were examined,including rock types,sedimentary facies,typical sedimentary sequences and sedimentary modes. The results indicate that the rocks of Taiyuan Formation in the central and eastern parts of the Ordos Basin can be classified into three categories: marine carbonates,peperite and terrigenous clastic rocks,which can be further subdivided into 15 types. The marine carbonate platform facies can be further categorized into seven sedimentary microfacies,including clastic beach,interbeach sea,supratidal zone(mud flat)and intertidal zone(mud flat). Six typical sequences in the transition environment from land to sea were identified based on detailed characterization of strata section. Sequences 1,2 and 3 consist of marine carbonate sedimentary sequences,and sequences 4,5 and 6 are composed of continental delta sedimentary sequences. The comprehensive analysis indicates that the Lower Permian Taiyuan Formation in the Ordos Basin underwent sedimentary evolution from a continental delta(clastic deposits)to a marine continental transition(mixed deposits)to a marine carbonate platform(carbonate deposits). Influenced by the sedimentary landform,the overall sedimentary filling pattern is characterized by “sandstone in the north and limestone in the south,overlaid with peat”. The research findings not only enhance the understanding of the sedimentary geology of Taiyuan Formation in the central and eastern parts of the Ordos Basin,but also establish an important theoretical doundation for the subsequent exploration of natural gas in the Taiyuan Formation.

Key words: Ordos Basin, Lower Permian, limestone, sedimentary characteristics, sedimentary model

中图分类号: 

• P618.13