峽東地區(qū)陡山沱組三段硅質(zhì)條帶中的微體化石分布特征及其控制因素

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[分類號]P52 [文獻標志碼］A

Abstract： In this study，we perform paleontological and sedimentary research of three sections， Tianjiayuanzi， Jiulongwan，and Qinglinkou，located within the carbonate platform of the Huangling Anticline inthe easter Three Gorgesarea，YichangCityHubei Province.Theaimis toinvestigate thespatial distributionpaternsofmicrofosilsin silicifiedbands from the lower Member IIofthe Doushantuo Formation and their potential controlling factors.The resultsshowthat silicified bandsand nodules in the Tianjiayuanzisection contain abundantacritarch fosils，tubular fossils，and cyanobacteria，along with oolitic grains and intraclasts.The Jiulongwan section contains sparse acritarch fossils and fragmented tubular fossils， with localized accumulations of ooliticsandy clasts，occasional gravel clasts， and mior thrombolites.The Qinglinkou section is dominated by lithified microbial mats and fine sandy grains，with rare thrombolitesobserved.Basedonthese findings，itisinferred thatduring thedepositionof thelowerMember II of theDoushantuo Formation（1）the Tianjiayuanzi sectionhadan intertidal flat environment，（2）the Jiulongwan section occupied an upper subtidal zone，and （3）the Qinglinkou section was situated between a lower subtidal zone and normal wave base.The variations in microfossil assemblage diversity and abundance among these study sections mayreflect taphonomic influence; that is，fossils inshallow-water sections are preserved due to therapid formationof siliceous nodules during early burial. Lower biodiversity in deeper water environments could be atributed to rapid microbial decompositionof planktonic acritarchs in the water column or during early burial in sediments，which is an important source of marine dissolved organic carbon.

Key words：Ediacaran period；Doushantuo Formation；sedimentary environment；fossil distribution diference

埃迪卡拉紀（ 635～539Ma 是雪球地球和寒武紀生命大爆發(fā)之間的關(guān)鍵轉(zhuǎn)折時期（Knollet al.，2004，2006;XiaoandNarbonne，2020）。（剩余31507字）