Lithostratigraphy and biostratigraphy of Middle and Late Permian strata in Illanlu stratigraphic section, North Qareh Ziaaeddin

Permian deposits crop out in the North East QarehZiaaeddin (Illanlu section) consisting Dorud, Ruteh, Nesen and Elli Bashi formation respectively. In this section, the Ruteh Formation composes about 751.3m of dark to grey, medium to massive limestone. The Nesen Formation contains approximately 627.3m of shaly limestone, shale and marl and finally the Elli Bashi formation contains about 22.7m grey thin nodular limestone, Red limestone and colored shale. The lower boundary of marine sequence is marked disconformably by Dorud Formation and upper boundary is conformable and continuous with Early and middle Elika Formation. On the basis of stratigraphical distribution of microfossils chiefly foraminifera five Assemblage biozoneswere distinguished includingTetrataxis-Globivalvulina-Nankinella Assemblage Biozone (Kubergandian), Langella-Geinitzina Assemblage Biozone (Early to Middle Murghabian), Paraglobivalvulina-Pachyphloia Assemblage Biozone (Late Murghabian to Midian), Codonofusiella-Palaeotextolaria Assemblage Biozone(Midian), Frondina-Hemigordius-Cribrogenerina Assemblage Biozone (Dzhulfian). The identified microfossils suggest Kubergandian to Dorashamian ages (Middle to Late Permian) for carbonate sequences of Permian at the study area. On the basis of lithological changes 15 lithozone were also recognized.With regards to lithological and paleontological characteristics and sequence thickness of marine sequence the Illanlu section is proposed as standard section for Middle and Late Permian stages.