HR: 1340h
AN: PP43A-0656    [Abstracts]
TI: Environmental Changes on the Eastern Black Sea Shelf During the Last 12 ka
AU: * Ivanova, E
EM: eivanova@geo.sio.rssi.ru
AF: Shirshov Institute of Oceanology, Russian Academy of Sciences, 36, Nakhimovsky Prosp., Moscow, 117997 Russian Federation
AU: Murdmaa, I
PP43A-0656 AF: Shirshov Institute of Oceanology, Russian Academy of Sciences, 36, Nakhimovsky Prosp., Moscow, 117997 Russian Federation
AU: Cronin, T
PP43A-0656 AF: 926A USGS National Center, 12201 Sunrise Valley Drive, Reston, Va 20192 United States
AU: Tchepalyga, A
PP43A-0656 AF: Institute of Geography, Russian Academy of Sciences, 29 Staromonetny Per., Moscow, 119017 Russian Federation
AU: Levchenko, O
PP43A-0656 AF: Shirshov Institute of Oceanology, Russian Academy of Sciences, 36, Nakhimovsky Prosp., Moscow, 117997 Russian Federation
AU: Howe, S
PP43A-0656 AF: Department of Earth and Atmospheric Sciences, ES-351, University at Albany, 1400 Washington Avenue, Albany, NY 12222-0001 United States
AB: Five transgressive-regressive cycles overprinted on the general trend of glacioeustatic sea level rise during the last 12 ka are well represented in micro- and macrofossil assemblages, sedimentation rates, and sediment grain size variations on the Caucasian Black Sea shelf. The oldest recovered sediments refer to the Neoeuxinian semi-freshwater basin (10.5 - 9 ¹⁴ C ka BP) with Caspian-type mollusk fauna and very low oxygen and carbon isotope values. The first appearance of marine mollusks and ostracodes from the Mediterranean is established in this part of the sea at 8.2 ¹⁴ C yr BP. The Early Holocene (Bugazian to Vityazevian)condensed section with at least two hiatuses and transitional faunal assemblages represent a high-energy shelf edge facies. A mixture of Caspian and Mediterranean elements suggests a dual-flow regime via the Bosporus since this time. Caspian species disappear and oligohaline species strongly decrease in abundance during the Vityazevian-Prekalamitian cycle. Later on, low sea level stands are generally characterized by shell layers, whereas silty mud with variable amounts of mollusk and ostracod shells rapidly accumulated during transgressions. Restricted mud accumulation, as well as benthic faunal composition and abundance, suggest a higher energy and better ventilation of bottom water during low sea level stands, than occurred during high stands. A trend of slight upward ¹⁸ O enrichment in mollusk shells points to an increase in bottom-water salinity during Vityazevian to Kalamitian (7 - 5 ¹⁴ C ka BP) transgressions due to a more open connection with the Mediterranean. A pronounced increase in polyhaline species abundance is established since Kalamitian and Djemetean transgressions (6.4 - 2.8 ¹⁴ C ka BP). Rather diverse benthic foraminifers and ostracodes thrived on the shallow shelf during the Holocene whereas the salinity was too low for planktic foraminifers.
DE: 1637 Regional climate change
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 3022 Marine sediments: processes and transport
DE: 3030 Micropaleontology (0459, 4944)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005