Evidence of Barremian climate based on calcareous nannofossils at Garau Formation (Qaleh-Darreh section)

Barremian sediments of the Garau Formation have been investigated at the southwest of the Kabir-kuh anticline (Qaleh-Darreh section) with regard to calcareous nannofossils. According to the presence of index calcareous nannofossils, NC5 biozone and NC5c, NC5d and NC5e subzones of Roth (1978) and CC5-CC6 biozones of Sissingh (1977) have been identified. At the studied interval, warm water taxa like Cyclagelosphaera margerelii, Diazomatolithus lehmanii, Lithraphidites carniolensis, Micrantholithus spp., Nannoconus spp., Rhagodiscus asper and Watznaueria spp. have been recorded along with cool water taxa such as Biscutum constans, Helenea chiastia and Zeugrhabdotus embergeri. The abundance of warm water taxa is higher than cool water taxa and a reverse trend can be observed between them. Regarding cool and warm water taxa three warming phases and two cooling phases are identified which includes the warming event of early Early Barremian, cooling event of Early Barremian, warming event of Mid-Barremian, cooling event of late Barremian and warming event of Barremian-Aptian boundary. It must be mentioned that these data are in accord with other parts of the world in the Tethyan (e.g., Italy) and the Boreal realms (e.g., NW Germany and NE England).
Keywords: Barremian, Biostratigraphy, Paleoecology, Garau Formation, Calcareous nannofossils