New Albian (Cretaceous) radiolarian age constraints for the Dumak ophiolitic mélange from the Shuru area, Eastern Iran

Abstract

The Dumak ophiolitic mélange is part of the nearly complete Neh Ophiolite Complex in Eastern Iran. This complex exhibits a typical ophiolite suite that consists of mantle peridotite, cumulates, gabbro, sheeted dikes, pillow basalt and a sedimentary cover including pelagic and shallow-water deposits. A sequence of red radiolarites intercalated with mid-oceanic ridge-related basalt and pelagic limestone was examined from the Shuru part of the Dumak ophiolitic mélange. A relatively well-preserved and diverse radiolarian assemblage was extracted that includes 25 genera with 19 spumellarian and 26 nassellarian species. The radiolarian microfauna from the Shuru section provides the first biostratigraphical data which establishes a Cretaceous, middle Albian age for the ophiolitic mélange. The new age data contribute to a better understanding of the geodynamic evolution of the eastern branch of the Neotethys.