Ostracode of Sinocytheridea Genus in Geological History of Peter the Great Bay (Pan-Sea of Japan)

Far East Branch of Russian Academy of SciencesPromoting Environmental Pesearch in Pan-Japan Sea Area : Young Researchers\u27 Network, Schedule: March 8-10,2006,Kanazawa Excel Hotel Tokyu, Japan, Organized by: Kanazawa University 21st-Century COE Program, Environmental Monitoring and Prediction of Long- & Short- Term Dynamics of Pan-Japan Sea Area ; IICRC(Ishikawa International Cooperation Research Centre), Sponsors : Japan Sea Research ; UNU-IAS(United Nations University Institute of Advanced Studies)+Ishikawa Prefecture Government ; City of Kanazaw

The Holocene Black Sea reconnection to the Mediterranean Sea: New insights from the northeastern Caucasian shelf

Recent findings about the evolution of palaeogeographic conditions of the Black Sea during the Holocene have significantly improved our understanding of the profound environmental changes that took place around 9 ka ago, when the Neoeuxinian Lake reconnected to the global ocean. In contrast to the western and southeastern regions where numerous studies have been recently performed, the northeast region remains relatively under investigated. We carried out the first multi-proxy continuous study of a sediment core (Ak-2575) from the northeastern Black Sea shelf that includes benthic calcareous fossils (ostracods, molluscs and foraminifers), dinoflagellate cysts (dinocysts) and sedimentology, thus providing reconstructions of surface and bottom-water conditions. The age model of the core is based on 10 AMS-14C dates. Calibrated ages are used throughout the manuscript. The first appearance of Mediterranean elements is documented at 9.6 cal. ka BP. Our data provide evidence of sustained cohabitation of benthic species of Caspian and Mediterranean origins, represented by different ontogenetic stages, from at least ~ 7.8 (or even 8.8) to 6.7 cal. ka BP with the gradual disappearance of brackish species suggesting a gradual increase in salinity and most likely a change in the salt composition. Dinocyst assemblages show species succession that is coherent across the Black Sea basin, with brackish taxa dominating until ~ 8.5 cal. ka BP and being slowly replaced by euryhaline species. The occurrences of authigenic gypsum crystals, especially abundant at ~ 7.4 and 6.5 cal. ka BP, suggest the temporal appearance of hydrogen sulphide at the shelf edge which during certain periods appears to reduce the abundance of benthic fauna

The Holocene history of the NE Black Sea and surrounding areas: An integrated record of marine and terrestrial palaeoenvironmental change

Here we present an almost complete and integrated Holocene record of marine and terrestrial palaeoenvironmental change from the NE shelf of the Black Sea. A dinoflagellate cyst record used to reconstruct Holocene sea-surface conditions highlights that the NE shelf was a brackish water environment, with a minimum salinity of 7 psu in the early-Holocene before changing at a gradual rate to a more saline environment with maximum salinities of ~18 psu being reached around 3 cal. ka. A warming phase was detected from 6 cal. ka BP, with warmest conditions between 3 and 2.5 cal. ka BP. A pollen record is used to examine the major climate and land-use changes in the eastern Black Sea region. Biome reconstructions show that the temperate deciduous forest dominates throughout the record, although with an overall decline. From early-Holocene to the first hiatus around ~9 cal. ka BP, Pinus pollen dominates, while taxa representing a mixed oak-hornbeam-beech forest are less abundant, indicating relatively cool and dry conditions. Between ~7.9 and ~6.1 cal. ka BP, a thermophilous deciduous forest established, suggesting an overall warming trend and humid conditions. From 4 cal. ka BP, Pinus dominates the pollen record, accompanied by an increase of herbs, implying an opening of the landscape, which would coincide with the beginning of the Meghalayan Age. The integrated record of the marine and terrestrial climate indicators supports the notion that this change in landscape may have been triggered by a combination of warmer and drier conditions and human activities in this region