沉积学报2025，Vol.43Issue(4)：1213-1232,20.DOI:10.14027/j.issn.1000-0550.2024.120
鄂尔多斯盆地西缘奥陶系乌拉力克组混积岩岩相类型及沉积模式
Lithofacies and Sedimentary Model of Migmatites in the Ordovician Wulalike Formation,Western Edge of the Ordos Basin
摘要
Abstract
[Objective]Several recent exploration wells in the Ordovician Wulalike Formation at the western edge of the Ordos Basin have obtained industrial gas flow,breaking through the largely unexplored migmatite zone.Under-standing the lithofacies and sedimentary characterisitcs of mignatites can provide theroretical basis and practical data for future oil and gas exploration work in the western edge.[Methods]Based on typical drilling core and outcrop da-ta,this study comprehensively utilizes thin sections,scanning electron microscopy,and logging to investigate the lithofacies,sedimentary facies,and distribution patterns of the Wulalike Formation in the western edge.[Results and Conclusions]The rocks of the Ordovician Wulaike Formation in the western edge of the Ordos Basin can be di-vided into three types:Migmatite lithofacies,terrigenous clastic lithofacies,and carbonate lithofacies.The vertical sequence combination is controlled by two periods of marine transgression events,while the lithofacies changes are further controlled by local hydrodynamic conditions.Lithofacies types,vertical sequences,logging,geochemistry and other facies indicators indicate that the Wulalike Formation can develop platforms,continental shelves,slopes,and basins,which can be further divided into 7 subfacies and 15 microfacies.The eastern platform facies feature"in-tertidal shoal-flat"sequence and the"tidal storm-channel-sand dam"sequence,and the sequence of"continental shelf storm shoreline/shallow sea sand bars"and"continental shelf mud"forms the central continental shelf facies.The western slope basin facies are dominated by turbidite fans,canyon channels,and basin mud.The distribution pattern of sedimentary facies within the third order sequence of the Wulaike Formation indicates that during the for-mation of sequence SQ1,the water body was generally deep and developed large sections of shale,while during the sedimentation of sequence SQ2,the water body became shallower as a whole.In addition,due to the influence of mi-crobial construction and the connection between the western edge and the middle-east platform,the slope and shelf facies also became narrower overall and retreated westward.Sedimentary model displays that rock types and sedimen-tary characteristics of the Wulaike Formation are mainly influenced by the source supply,paleogeomorphological fea-tures,and hydrodynamic conditions,among which sufficient source supply is the basic condition for migmatites sedi-mentation in the western edge area.关键词
鄂尔多斯盆地/乌拉力克组/混积岩/岩相/沉积相Key words
Ordos Bain/Wulalike Formation/migmatites/lithofacies/sedimentary facies分类
天文与地球科学引用本文复制引用
白莹,马占荣,黄正良,闫伟,高建荣,赵振宇..鄂尔多斯盆地西缘奥陶系乌拉力克组混积岩岩相类型及沉积模式[J].沉积学报,2025,43(4):1213-1232,20.基金项目
中国石油天然气股份有限公司科学研究与技术开发项目(2022KT0302)China National Petroleum Corporation Scientific Research and Technological Development Project,No.2022KT0302 （2022KT0302）
