Biostratigraphy,Microfacies,Sedimentary Environments and Sequence Stratigraphy of the Late Devonian-Carboniferous Deposits at the Anarak Section,Central Iran

The Late Devonian-early Carboniferous deposits of the Anarak section in northeastern Isfahan,Central Iran,evaluated based on conodont biostratigraphy,sedimentary environment and sequence stratigraphy.According to the field observations,five lithological units were identified.Investigating the conodont fauna of the Late Devonian-Carboniferous(Mississippian-Pennsylvanian)deposits of Bahram,Shishtu,and Qaleh(Sardar 1)formations in Anarak section led to the identification of 67 species of 18 conodont genera,and accordingly 22 conodont biozones were differentiated.The correlation of sea-level change curves,regarding to the conodont biofacies with the global sea-level curve,demonstrates the relative correlation in the mentioned times due to the shallow condition of the central Iran basin compared to the European and American basins.The microfacies analysis led to the identification of 12 microfacies related to the open sea,bioclastic barrier,lagoon and tidal flat sub-sedimentary environments in a homoclinal carbonate ramp environment.Based on sequence stratigraphy studies,three 3rd order sequences were identified.The first sequence,which is of the Late Devonian(upper part of the Bahram Formation,32.5 m),the second sequence(12.5 m)is the Late Devonian(uppermost part of the Bahram Formation),and the third sequence(68 m)is the early Carboniferous(the Shishtu I Formation).

Biostratigraphy and Sequence Stratigraphy of the Gurpi Formation at Deh Dasht Area, Zagros Basin, SW Iran

A rich assemblage of planktonic foraminifera has been studied from an outcrop of the Gurpi Formation, the hydrocarbon source rock in the southwest Iran, Deh Dasht area(Kuh-e Siah anticline). Based on the distribution of the planktonic foraminifera, eight biozones have been recognized that included:Dicarinella concavata Interval Zone(Earliest Santonian), Dicarinella asymetrica Total Range Zone(Santonian to Earliest Campanian), Globotruncanita elevata Partial Range Zone(Early Campanian), Globotruncana ventricosa Interval Zone(Middle to Late Campanian), Radotruncana calcarata Total Range Zone(Late Campanian), Globotruncanella havanensis Partial Range Zone(Late Campanian), Globotruncana aegyptiaca Interval Zone(Late to latest Campanian), Gansserina gansseri Interval Zone(Latest Campanian to Early Maastrichtian). These biozones indicates that the Gurpi Formation deposited during the Early Santonian- Early Maastrichtian. These biozones are compared to the most standard biozones defined in Tethysian domain. Based on distribution of morphotype groups of planktonic foraminifera, planktonic to benthic ratio(P/B) and content of carbonate, nine third-order sequences are recognized.