Microfacies analysis and depositional environment of the Upper Devonian Dankovo-Lebedyansky sediments,Tatarstan,Volga-Ural Basin,Russia  

作　　者：Ibrahem Yousef V.P Morozov A.N Kolchugin V.Sudakov I.Idrisov A.Leontev 

机构地区：[1]Kazan Federal University,Institute of Geology and Petroleum Technologies,420008,Russian Federation

出　　处：《Petroleum Research》2023年第2期244-255,共12页石油研究（英文）

基　　金：supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2022-299 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves”.

摘　　要：The Upper Devonian,Middle Famennian Dankovo-Lebedyansky sediments in Southeast Tatarstan territory are a carbonate sequence composed of limestone and dolomite,which is important hydrocarbon reservoir units,therefore,it is necessary to conduct in-depth study on its microfacies and depositional environment.In this study,a multidisciplinary approach that combines core observation with thin section examination is used.The limestone contains abundant skeletal grains(echinoderms,foraminifera,algae,gastropods,and calcispheres),as well as non-skeletal grains(intraclasts and peloids).On the basis of detailed petrographic investigations,six sedimentary microfacies can be identified,including(i)peloidal grainstone(MF 1),(ii)cemented bioclastic peloidal grainstone(MF 2),(iii)echinodermconcentrated packstone(MF 3),(iv)algae packstone(MF 4),(v)bioclastic wackestone(MF 5),(vi)whole-fossil wackestone(MF 6),as well as dolomite or dolostone as diagenetic facies(MF 7).Based on microfacies analysis,the Dankovo-Lebedyansky sediments were deposited in three distinct sedimentary facies belts(shoal,lagoon and open marine environment).In order to reflect dispositional energy condition,the microfacies were grouped into facies associations:(i)low-energy microfacies associations including MF 5 and MF 6,(ii)moderate energy microfacies associations including MF 1,MF 2,MF 3,and MF 4.The dolomite,or diagenetic facies(MF 7),is the result of slightly to extensively dolomitization of limestone in the Dankovo-Lebedyansky sediments.Most of frequent dolostone types are euhedral planar-e and subhedral planar-s.According to petrographic characteristic of the dolostone,a seepage reflux model can be used to explain the dolomitization process of Dankovo-Lebedyansky sediments.

关 键 词：MICROFACIES Depositional environments CARBONATE DOLOMITIZATION Upper devonian Dankovo-lebedyansky Volga-ural basin 

分 类 号：P53[天文地球—古生物学与地层学]