Biostratigraphy and Paleoecology of Maastrichtian Sediments in the Zagros Basin, Iran

To enable the lithostratigraphic and biostratigraphie study of the Gurpi Formation, within the ＇Dezak＇ or Globigerina Marl, a stratigraphic section at Booraki, located to the NNW of Shiraz, SW Iran, through the late Cretaceous was examined. The formation consists of shale and greenish-gray marls interbedded with cream limestone, brown sandstones and siltstones with an exposed thickness of 160 m in the studied section. Samples were taken at regular intervals in all yielding 14 genera and 16 different species of benthic and planktic foraminifera that allowed determination of the age of the beds as Maastrichtian. To examine the paleoecology of the formation, some important ecological factors including water level, salinity, and oxygen regime change during the depositional courses of the formation were analyzed. The density of foraminiferans decreases from the base to top of the Gurpi Formation whereas the ratio of planktic to benthic Foraminifera （i.e., P/B） and proportion of shallow-water fauna increase. These foraminiferal changes indicate an increase and decrease in depth, temperature, salinity and oxygen, respectively, at the base and top of the Formation.

Microfacies and Sedimentary Environments of the Fahliyan Formation from the Southwest of Iran (Shiraz, Zagros)

The Fahliyan Formation is a carbonate sequence of Lower Cretaceous (Berriasian-Hauterivian) in age and was deposited in the Zagros sedimentary basin. This formation is a part of Khami Group and is a reservoir rock in Zagros Basin. This formation was investigated by a detailed petrographic analysis in order to clarify the depositional facies and sedimentary environment in the Kuh-e-Gadvan in Fars Province. Petrographic studies led to the recognition of nine microfacies that were deposited in four facies belts: tidal flat, lagoon, and barrier and shallow open-marine. An absence of turbidite deposits, reefal facies, and gradual facies changes indicate that the Fahliyan Formation was deposited on a carbonate ramp.

Biostratigraphy of Albian Sediments(Kazhdumi Formation)in Zagros Area(Southwest of Iran)

To investigate biostratigraphy of Albian sediments(Kazhdumi Formation)in the Zagros Basin,280 samples in four sections were prepared which are nominated as Murshan-e-Bala,Fahliyane-Pain,Kupon and Tale-e-Afghani.Stratigraphic distribution of identified foraminifers confirms well developed orbitolinids which are associated with other Albian benthic foraminifers in all studied sections.The orbitolinids are recognized in surrounding strata[Dariyan(at the base which is marked by an oxidized zone)and Sarvak Formations(on the top,as gradtional contact)]as well as the Kazhdumi Formation.Obtained biostratigraphic data show that Early Albian is marked by the presence of Hemicyclammina sigali,which co-occurs with Mesorbitolina texana and Mesorbitolina subconcava,whereas Conicorbitolina conica and Meorbitolina parva support Late Albian age of the studied sections.Calcareous algae are associated with both benthic faunal assemblages.Albian planktons occur in the studied sections which are identified as Favusella washitensis and Calcisphaerula inomminata subzones.The stratigraphic position of planktons actually indicates vertical displacement in the sedimentary basin during Albian time.Other associated Albian pelagic foraminifera are identified which are obviously recognized in three sections of the Kazhdumi Formation.The presence of pelagic species in the study section of the Kazhdumi Formation indicates basement faulting during the Albian period.