Biostratigraphy and paleoenvironmental significance of Paleogene foraminiferal assemblages from Dashte Zari area in High Zagros, West Iran

Abstract

The Paleogene carbonate deposits of Pabdeh and Jahrum formations are widespread from the northwest (Dashte Zari area) to the southwest of the Shahrekord region in the High Zagros Mountains of Iran and record the lateral and upward transition from open marine into the shallow water environment. The Pabdeh Formation shows a succession of open marine pelagic and hemipelagic limestone, argillaceous limestone, and argillaceous chert. It consists of planktonic wackestone, pellet-planktonic wackestone, mudstone with planktonic foraminifera, and radiolarian siliceous wackestone, which accumulated within the Zagros Foreland Basin. The planktonic foraminifers are assigned to the Late Paleocene–Late Eocene and correspond to subtropical and tropical Zones P4b–E15. The Jahrum Formation is represented by bioclast-bearing limestone and calcarenite. It consists of benthic foraminiferal wackestone, benthic foraminiferal-red algal packstone, and bioclast-intraclast packstone deposited in a shallow platform environment. The Jahrum Formation is inter-fingered in the upper part of the Pabdeh Formation and finally overlies it conformably during the Bartonian–Priabonian. Shallowing and off-lap relationships record basin shrinking, while repeated inter-fingering signals moderate tectonic subsidence. Both formations are disconformably covered by the Late Oligocene–Miocene Asmari Formation. Keywords: biostratigraphy, Pabdeh Formation, Zagros, Paleogene, Iran.

Petroleum Geology of the Cenozoic Succession in the Zagros of Sw Iran: A Sequence Stratigraphic Approach

“…Several studies investigating planktonic foraminiferal biozonations for the deep-water Pabdeh Formation marls have followed global biozonal schemes (e.g. Iaccarino et al, 2005;Spezzaferri, 1994;Wade et al, 2011;Pearson and Wade, 2009;Babazadeh and Cluzel, 2022). Increasingly, calcareous nannofossil data is being used to improve biostratigraphic resolution (e.g.…”