Mid-Cretaceous radiolarian faunas from the Ashin Ophiolite (western Central-East Iranian Microcontinent)

• Published in: Cretaceous research 2015-09, Vol.56, p.110-118
• Main Authors: Shirdashtzadeh, Nargess, Kachovich, Sarah, Aitchison, Jonathan C., Samadi, Ramin
• Format: Article
• Language: English
• Subjects: Ashin ophiolitic mélange; Central-East Iranian Microcontinent; Cretaceous; Radiolarian chert
• ISSN: 0195-6671; 1095-998X
• DOI: 10.1016/j.cretres.2015.04.003

The Ashin ophiolitic mélange crops out in the west of the Central-East Iranian Microcontinent (CEIM). Accurate dating the deep-water radiolarian chert deposits associated with this ophiolite provide valuable data to constrain the stratigraphic and paleotectonic evolution this Neo-Tethyan oceanic basin. Chert nodules within Upper Cretaceous limestones and chert layers overlying pillow lavas of this ophiolite were collected and examined in detail for the first time. Radiolarians indicate that the cherts accumulated in the mid-Cretaceous in a deep marine setting within the eastern branch of the Tethyan Ocean in Iran. Two distinct radiolarian faunas, one mid-Albian (∼107 Ma) the other Turonian (∼94 Ma) were recovered. The radiolarian microfossil ages are consistent with radiometric ages previously obtained from associated plagiogranites and quartz keratophyre. This study indicates that mid-Cretaceous radiolarian assemblages from the western CEIM are similar to other radiolarian faunas reported from Cretaceous ophiolites in Greece, Turkey, Iran (Outer Zagros Ophiolitic Belt in Iran, e.g. Khoy, Kermanshah, Neyriz, and Soulabest), and southern Tibet in China. [Display omitted] •The first clearly imaged details of radiolarian fauna from Ashin Ophiolite.•Turonian and Albian (∼94 and 107 Ma) ages for chert deposits in Ashin ophiolite.•A deep marine setting for the eastern branch of Neo-Tethys in Iran.•Similarity of Ashin to Upper Cretaceous Neo-Tethyan basins from Greece to Tibet.