Facies, depositional environment and depositional model of the Qom Formation in northern Abadeh (Sanandaj–Sirjan fore-arc basin)

Mohammadi, Ebrahim; Ameri, Hamed

doi:10.22067/sed.facies.2021.42000

Facies, depositional environment and depositional model of the Qom Formation in northern Abadeh (Sanandaj–Sirjan fore-arc basin)

Document Type : Original Article

Authors

Ebrahim Mohammadi

Hamed Ameri

Department of Ecology, Institute of science, High technology and environmental science, Graduate University of advanced Technology, Kerman, Iran

10.22067/sed.facies.2021.42000

Abstract

The Qom Formation deposits in northern Abadeh (Sanandaj–Sirjan fore-arc basin) studied in order to analyze microfacies, depositional environment and depositional model. Outcrops of the Qom Formation in northern Abadeh, with Rupelian- Chattian in age and 85-m thickness, consist mainly of massive and bedded limestone, shale and conglomerate. The Qom Formation in northern Abadeh conformably overlies the LRF, and its upper boundary covered with quaternary alluvium. Foraminifera, coralline red algae and corals dominate biogenic components of the Qom Formation. Based on field investigations and microscopic studies, nine microfacies (six carbonate microfacies plus three terrigenous facies) were recognized. The conglomerate facies is deposited in braided streams; while, other facies are deposited in marine environment and on a ramp type platform. This ramp is generally dividable into two depositional environments including inner ramp (lagoon) and middle ramp (open marine). However, outer ramp deposits are not observed in the study area. The high abundance of larger benthic foraminifera, coral and corallinacea red algae indicates that deposition took place in tropical warm water.

Keywords

Qom Formation

Oligocene

ramp

Depositional model

Subjects