Foraminiferal paleoecology of an upper Cenozoic synorogenic conglomeratic succession in the Zagros basin, Iran

Abstract

The recently discovered carbonate–siliciclastic intervals within an upper Cenozoic synorogenic conglomeratic succession in the Shalamzar area of the Zagros sedimentary basin in central western Iran contain abundant and diverse assemblages of foraminifera. A total of 32 genera and 34 species of benthic and five genera and eight species of planktic foraminifera representative of Burdigalian age were identified. The foraminifera are classified into four morph groups of: (A) planktic, (B) deep benthic, (C) large benthic (robust hyaline, imperforate agglutinated and porcelaneous foraminifera) and (D) other benthic foraminifera. An outer shelf zone is represented by dominance of planktic and small benthic foraminifera of the morph groups A and B. An inner–middle shelf is indicated by an association of dominant morpho group C and minor morpho group D. Also, a mixed biotic assemblage of abundant morpho group D and sparse morpho group C reflects an inner shelf zone. Based on the biodiversities and morpho groups, the foraminifera were inhabitants of a dysoxic–oxic marine paleoecosystem between ca 120 m depth with low-to-moderate to high water energy in a euphotic to oligophotic zone. Moreover, normal seawater salinity to slightly hypersaline conditions (34 to slightly more than 50 psu) is reflected by the morpho groups.