Historical literature may constitute a valuable source of information to reconstruct sea level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a literature survey, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes. Two articulated bivalve shells from the marine facies were radiocarbon dated and calibrated to establish a chronology and to compare them with historical findings. The overall results indicate a high-stand during the Little Ice Age, up to −19 m, with a −28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at −26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin could create locally changes in base level. These local base-level changes should be considered in any CSL reconstruction
Abstract. Historical literature may constitute a valuable source of information to reconstruct sea-level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a comprehensive literature review, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes and to compare the results with other geological and historical findings. The overall results indicate a high-stand during the Little Ice Age, up to −21 m (and extra rises due to manmade river avulsion), with a −28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at −26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin creates local changes in base level. These local base-level changes should be considered in any CSL reconstruction.
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.
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