Biostratigraphy and paleo-ecological reconstruction on Scleractinian reef corals of Rupelian-Chattian succession (Qom Formation) in northeast of Delijan area

Abstract

In this research, biostratigraphy and paleo-ecological reconstruction of the Qom Formation deposits in Bijegan village, northeast of<br />Delijan, are discussed. The studied section is situated in the western margin of the Urumieh-Dokhtar magmatic arc (the intra-arc basin).<br />The Qom Formation deposits at the studied area are Rupelian-Chattian in age. Larger benthic foraminifers are used for biostratigraphy<br />with the occurrence of 14 genera and 16 species, which led to the identification of two faunal assemblages: 1 Nummulites vascus-<br />N.fichteli, and 2. Lepidocyclina-Operculina-Ditrupa. Oligocene coral assemblages from the studied section are investigated with regard<br />to its palaeoecological implications. These corals comprise four species of four genera and are compared with faunas from the<br />Mediterranean Tethys and Indo-pacific Ocean, and they have an affinity to corals of the Mediterranean Tethys. Re-deposited branching<br />Porites coral assemblages probably occurred in patchy dense frameworks which were destroyed during storm events and re-deposited<br />in the present stratified horizons. The Porites-Faviidae assemblage represented a common feature of Oligocene coral faunas and<br />increasing water energy.<br />