Writers : Keshani,F.
Refference : Geosciences Scientific Quarterly Journal,No.:21-22,P.:2
Publishing Year : 1375

Abstract :

Well- preserved radiolarian fossils were found In the Nayriz pelagic and bedded radiolarian chert and coloured, siuicous shale. on the Gardaneh Estahbanat- Nayriz in the south west of Bakhtegan Lake. Based on correlation with the radiolarian Zonations of western North America and other areas of Neotethys, the age of these silicous rocks can be assigned as Early Cretaceous (upper Valanginian) and Late Cretaceous (Lower Cenomanian).
By determining radiolarian fauna, we can conclude that, there are six alternate thrust sheets belonging to Lower Cenomanian and upper Valanginian respectively. This provides important evidence for reconstructing geological history of the Tethys of the region and shows radiolarians to be very Important stratigraphic tools in long distance correlation, even between different paleogeographic realms. For the first time in Iran, they represented twenty Families, fifty Genera, eighty Species and three Subspecies of Radiolaria from this area.
In addition, 3 Acre zones (Range zone) and 7 assemblage zones in the upper Valanginian and 12 Assemblage zones in the lower Cenomanian had been distinguished.

Subject List : Radiolaria