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标题：Biostratigraphy and Geochemistry of Upper Paleocene - lower EoceneOceanic Red Beds from the Zagros Mountains, SW Iran
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作者：Manooseh P Khavari Khorassani ; Ebrahim Ghasemi-Nejad ; Michael Wagreich 等
期刊名称：Journal of Earth Science & Climatic Change
电子版ISSN：2157-7617
出版年度：2015
卷号：6
期号：8
页码：1-8
DOI：10.4172/2157-7617.1000302
语种：English
出版社：OMICS International
摘要：Oceanic Red Beds studied are well known in the upper Cretaceous (CORBs, i.e. Cretaceous Oceanic Red Beds), but their presence and genesis have hitherto not been intensively discussed for equivalent Paleogene deposits. We describe a red to purple shale interval from the Pabdeh Formation, Zagros basin, Iran, which can be assigned to Late Paleocene to Early Eocene age, nannofossil zones NP9-NP12. Parts of the purple marl interval within NP9/NP10 coincide with the PETM (Paleocene-Eocene Thermal Maximum) interval. Coccolithus pelagicus, Sphenolithus moriformis, Sphenolithus orphanknollensis, and Toweius ssp. are dominant in nannofossil assemblages in this interval, and PETM event taxa such as Discoaster araneus appear. Based on whole rock geochemistry and microfossil assemblages, the red to purple marls were deposited in an oligotrophic environment with low nutrient (Ba) values, and were accompanied by a shift to more oxic conditions and low amount of TOC in an oceanic basin. Low amount of major elements like Si, Al and Fe indicates low terrestrial input and relatively high amount of CaO (biogenic element) emphasizes the open sea and pelagic deposition of the shale. Warm deep water can be inferred by the presence of the dinoflagellate taxa Impagidinium and nannoplankton taxa, Discoaster. As a result, the purple shale can be considered as typical Paleogene ORBs in the Zagros basin deposited under very similar conditions as well studied Tethyan Cretaceous oceanic red beds.
关键词：Oceanic red beds; purple shale; Tethyan realm; Zagros