New biostratigraphic data from Cretaceous planktic foraminifera in Sahlabad province, eastern Iran

Abstract

The foraminiferal content of two stratigraphic sections, located in eastern Iran within the Sahlabad province, between the Lut and Afghan blocks and ranging in age from Turonian to Campanian is investigated. Previous studies were general and only indicated the presence of planktonic foraminifera in this province. This paper presents a detailed study of planktonic foraminifera of the Shirshotor unit and establishes for the first time a local biostratigraphy consisting of five biozones. Biozones from the upper Turonian to lower Campanian are recognized, but the upper lower Campanian to lower upper Campanian strata are missing, as demonstrated by the lack of the Globotruncana ventricosa biozone. Tectonic activity in this region during the late early Campanian and mid-Campanian resulted in the presence of an unconformity together with debrites (debris flow deposits) in the lower upper Campanian. About twenty-five planktonic foraminiferal species are reported and illustrated. The largest faunal diversity is encountered in the upper Santonian. The planktonic foraminiferal biozones are precisely defined in selected stratigraphic sections and allow age determinations for the deepest marine sediments (pelagic limestones and bedded cherts) before the collision of the Lut and Afghan blocks.