Facies Analysis and Depositional Environment of the Mulussa Formation at the Ga'ara Depression, West of Iraq

A detailed study on the facies and depositional environment of the Mulussa Formation (Carnian-Norian) at the southern rim of Ga'ara depression, west of Iraq is carried out. The investigation is based on ninety six thin sections collected from five outcrop sections. This formation is dominantly composed of carbonate, marls and subordinate sandstone. Three lithofacies are recognized, depending on field description and microscopic examination, namely: dolomite, dolomitic sandstone and marl. The dolomite lithofacies is divided into four main microfacies, namely: dolomitized lime mudstone (four submicrofacies), dolomitized wackstone (two submicrofacies), dolomitized packstone (three submicrofacies) and dolomitized algal boundstone. Dolomitic sandstone lithofacies is two microfacies, namely: calcarenite and basal conglomerate of sandstone microfacies. By facies analysis, the deposition of Mulussa Formation took place in subtidal, lagoon, tidal flats, tidal ponds, tidal channels and coastal dunes. It generally represents deposition in shallow inner shelf environment with some continental influence in hot, arid to semi-arid climate. Keywords: facies analyses, depositional environment, carbonate rocks, Mulussa Formation, Ga'ara depression, Iraq

Facies Analysis and Depositional Environment of the Rus and Jil Formations (l- Eocene) in Najaf and Samawa Areas, Southern Iraq

This research deals with study of facies and depositional environment of the lower Eocene Rus and Jil Formations at Najaf and Samawa Governorates, Southern Iraq. Two major lithofacies are recognized in the studied sections, namely carbonate and evaporite lithofacies. The carbonate lithofacies is divided into five microfacies whereas the evaporite lithofacies is divided into three Sublithofacies.From facies analysis the Rus and Jil Formations, in the study area, represent deposition in a shallow carbonate rimmed platform. The Rus Formation consists of two shallowing upward successions each of them represents peritidal environment, i.e., beginning with subtidal followed by intertidal and culminated with supratidal setting. The Jil Formation consists of two shallowing upwards successions representing shelf to peritidal environments. The Jil Formation grades from open marine to sabkha, i.e., beginning open marine followed by shoal, subtidal, intertidal and culminates with supratidal setting. The abundance of evaporites indicates that the climate during their depositions is arid to semi-arid. Keywords: Facies, depositional environment, Rus Formation, Jil Formation, Sabkha