摘要： 山西沁水盆地上石炭统—下二叠统太原组含有重要的可采煤层和煤层气资源,并在该盆地东南部陵川县附城镇一带出露良好露头。基于对太原组露头剖面和部分钻孔资料的研究,综合分析了该组的岩性、沉积构造、实体化石、遗迹化石和沉积序列等沉积特征。(1)太原组灰岩形成于正常浅海(开阔台地)和局限海湾(局限台地)2种沉积环境,其中,L₁灰岩顶部、L₂灰岩中下部、L₄灰岩上部、L₅灰岩顶部、L₇灰岩顶部和L₈灰岩形成于局限海湾环境,其他灰岩层均形成于正常浅海环境;(2)根据太原组煤系岩性组合特征,划分出6个岩性段,各段中的碎屑岩及所含煤层形成于障壁岛(砂岛)、潟湖和潮坪环境中;(3)通过对沉积特征和沉积序列的分析,识别出11种沉积序列类型,提出了太原组煤系发育的岛湖潮坪、局限海湾(潟湖)潮坪和滨岸潮坪等3种聚煤环境模式。该成果可为沁水盆地东南部太原组煤及煤层气勘探与开发提供沉积背景方面的重要信息和理论支撑。

关键词: 沁水盆地, 石炭系—二叠系, 太原组, 沉积环境, 聚煤环境

Abstract: The Upper Carboniferous-Lower Permian Taiyuan Formation in Qinshui Basin contains important mineable coal seams and coalbed methane resources,and is well exposed in Fucheng town of Lingchuan County in southeastern Qinshui Basin,Shanxi Province. Based on the outcrop section observation and a part of borehole data of the Taiyuan Formation,the paper synthetically analyzed the lithologic features,sedimentary structures,body fossils,trace fossils,sedimentary sequence and some other depositional characteristics.(1)Carbonate rocks of the Taiyuan Formation in this area were formed in two sedimentary environments,i.e.,open shallow sea(open platform)and restricted bay(restricted platform),among which,the top of Limestone 1(L₁),middle-lower part of L₂,the upper part of L₄,the top of L₅,the top of L₇ and the L₈ were formed in a restricted bay environment,and other limestone beds were generated in an open shallow sea environment;(2)Based on the lithologic association characteristics of the Taiyuan Formation coal measures in the study area,six lithologic members were classified,and clastic rocks and coal seams in each member mainly were formed in sedimentary environments including barrier island(sand island),lagoon and tidal flat;(3)After analyzing sedimentary characteristics and sedimentary sequence,11 types of sedimentary sequences were distinguished and 3 types of coal-accumulating environment modes were proposed in the Taiyuan Formation coal measures of this area,including coal-accumulating environment of tidal flat associated with barrier island and lagoon depositional system,the coal-accumulating environment of tidal flat alongside restricted bay(lagoon),and the coal-accumulating environment of coastal tidal flat. The results may provide important information and theoretical supports of sedimentary background for coal and coalbed methane exploration and developing in the Taiyuan Formation of southeastern Qinshui Basin.

Key words: Qinshui Basin, Carboniferous-Permian, Taiyuan Formation, sedimentary environment, coal-accumulating environment

中图分类号: 

• P531