The present study deals with the depositional facies,diagenetic processes and sequence stratigraphy of the shallow marine carbonates of the Samana Suk Formation,Kohat Basin,in order to elucidate its reservoir quality.The Samana Suk Formation consists of thin to thick-bedded,oolitic,bioclastic,dolomitic and fractured limestone.Based on the integration of outcrop,petrographic and biofacies analyses,the unit is thought to have been deposited on a gentle homoclinal ramp in peritidal,lagoonal and carbonate shoal settings.Frequent variations in microfacies based sea-level curve have revealed seven Transgressive Systems Tracts(TSTs)and six Regressive Systems Tracts(RSTs).The unit has undergone various stages of diagenetic processes,including mechanical and chemical compaction,cementation,micritization,dissolution and dolomitization.The petrographic analyses show the evolution of porosity in various depositional and diagenetic phases.The fenestral porosity was mainly developed in peritidal carbonates during deposition,while the burial dissolution and diagenetic dolomitization have greatly enhanced the reservoir potential of the rock unit,as is further confirmed by the plug porosity and permeability analyses.The porosities and permeabilities were higher in shoal facies deposited in TSTs,as compared to lagoonal and peritidal facies,except for the dolomite in mudstone,deposited during RSTs.Hence good,moderate and poor reservoir potential is suggested for shoal,lagoonal and peritidal facies,respectively.

Emadullah KHAN;Abbas Ali NASEEM;Suleman KHAN;Bilal WADOOD;Faisal REHMAN;Maryam SALEEM;Mubashir MEHMOOD;Waqar AHMAD;Zubair AHMED;Tahir AZEEM

Department of Earth Sciences,Quaid-e-Azam University,Islamabad 45320,Pakistan;Department of Geology,Abdul Wali Khan University,Mardan 23200,Pakistan;Department of Geology,University of Peshawar,Peshawar 24420,Pakistan;State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 71006,China;Department of Geology,University of Swabi,Swabi 23561,Pakistan;Department of Earth&Environmental Sciences,Bahria University,Islamabad 44000,Pakistan;Department of Earth&Atmospheric Sciences,Universitv of Alberta,Edmonton T6G 2R3,Canada

地质学报（英文版）

[1]Emadullah KHAN;Abbas Ali NASEEM;Suleman KHAN;Bilal WADOOD;Faisal REHMAN;Maryam SALEEM;Mubashir MEHMOOD;Waqar AHMAD;Zubair AHMED;Tahir AZEEM-.Facies Analysis,Sequence Stratigraphy and Diagenetic Studies of the Jurassic Carbonates of the Kohat Basin,Northwest Pakistan:Reservoir Implications)[J].地质学报（英文版）,2022(05):1673-1692

Facies,Kohat,Samana,oolitic,bioclastic,dolomitic,biofacies,homoclinal,peritidal,lagoonal,Transgressive,Tracts,TSTs,RSTs,micritization,dolomitization,fenestral,permeabilities

Analysis,Sequence,Stratigraphy,Diagenetic,Studies,Jurassic,Carbonates,Basin,Northwest,Pakistan,Reservoir,Implications,present,study,deals,depositional,diagenetic,processes,sequence,stratigraphy,shallow,marine,carbonates,Suk,Formation,order,elucidate,its,reservoir,quality,consists,thin,thick,bedded,fractured,limestone,Based,integration,outcrop,petrographic,analyses,unit,thought,have,been,deposited,gentle,ramp,shoal,settings,Frequent,variations,microfacies,sea,level,curve,revealed,seven,Systems,six,Regressive,undergone,various,stages,including,mechanical,chemical,compaction,cementation,dissolution,show,evolution,porosity,phases,was,mainly,developed,during,while,burial,greatly,enhanced,potential,rock,further,confirmed,by,plug,permeability,porosities,were,higher,compared,except,dolomite,mudstone,Hence,good,moderate,poor,suggested,respectively

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