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Cores MAR02-45 and MAR05-03 were raised from 68–69 m water depth on the SW Black Sea shelf and indicate transgression and submergence beneath several tens of metres of water before 11.0 cal ka. Those who postulate a Black Sea lowstand below − 100 m until the approximately 9.1 cal ka reconnection with the world ocean have suggested that sites like MAR02-45 and MAR05-03 must have been located in perched lakes on what is now the modern shelf. However, the silt- and clay-fraction mineralogy of samples from MAR02-45 provides no evidence for a shift in provenance at 9.1 cal ka, with earlier input from local rivers and later input from a broader region. Sedimentary abundances of Sc, Fe, Co, Ce, La, Th and Y also show no significant downcore trends. These elements likely reside in aluminosilicate mineral grains shed from terrestrial sources, so negligible downcore variation suggests long-term continuity in the composition of the detrital supply. More critically, the volume of pre-9.1 cal ka sediment around the MAR02-45 and MAR05-03 sites is > 25 times the expected yield from local rivers over a 5000 year period, so other more substantial sources are required. The predominant silt size of the recovered sediments, the configuration of late Holocene currents in the western Black Sea, and analogies with dispersal systems elsewhere suggest that the bulk of the fine-grained muds at these sites likely came from the Danube and Kamchiya drainage basins where thick deposits of unconsolidated Pleistocene loess have been strongly dissected. To reach core sites on the SW Black Sea shelf, this material must have been advected from the Danube and Kamchiya deltas by unobstructed marine currents. Only thin event beds (tempestites) of fine sand and silt in the lower part of cores MAR02-45 and MAR05-03 are interpreted to have a local source in the Strandja Mountains of Thrace. Comparison of the palynology of surface samples from the Danube Delta and its associated coastal lagoons with the pre-9.1 cal ka sediments of core MAR02-45 confirms that the hypothesis of deposition in a perched ancient lake is untenable. [ABSTRACT FROM AUTHOR]

Seaward of the Bosphorus Strait, the south-west Black Sea shelf is dominated by the world's largest channel network maintained by a quasi-continuous saline ( ca 35 → 31 psu) underflow. Calculations indicate that >85% of the initial discharge of ca 104 m3s−1 spills overbank before the shelf edge. This paper documents interaction of the overspill with sea bed topography using multibeam bathymetry, echo-sounder images of the water column, conductivity-temperature-depth profiles and sediment cores. Overbank spill is widespread, particularly through crevasse channels and on the middle shelf where confinement by channel banks is negligible. Towards the outer shelf, the wind-driven Rim Current advects mud along the shelf, contributing to levée successions and deposition on stoss sides of elongate transverse ridges. Echo-sounder profiles reveal metre-scale eddies over megaflutes, and breaking lee waves and internal hydraulic jumps over ridges. Megaflutes reach 600 m long and 7 m deep, yet form where the underflow, outside the flute, is no thicker than ca 2 to 5 m. Two types of elongate seaward-facing ridges are recognized. Type 1 ridges, 2 to 5 m high, consist of bivalve-rich muddy sand in low-angle (3·5° to 6°) cross-sets created by the underflow. Type 2 ridges, ca 5 m high, have crests up to 2 km long and a buried wedge-shaped foundation (the 'ridge-core') comprised of facies similar to Type 1 ridges. These ridge-cores are blanketed on the landward side by stratified muds, and are capped by obliquely oriented ribs supporting a diverse benthic community. This facies distribution is interpreted to result from stoss-side and lee-side velocity and turbulence fluctuations induced by internal hydraulic jumps and breaking lee waves in overspilling portions of the underflow. Experimental results published by W.H. Snyder and co-workers effectively explain ridge evolution and flow across the ridges, and therefore can be applied with confidence to less easily studied deep-marine settings swept by turbidity currents. [ABSTRACT FROM AUTHOR]

An abstract of the article "Holocene paleoecology of the southwestern Black Sea shelf using ostracods as proxies," by Lorna R. Williams, Richard N. Hiscott, and Ali E. Aksu is presented.

Abstract: Core M02-45 recovered 9.5m of a ∼12m-thick transgressive succession on the SW Black Sea shelf. The underlying transgressive unconformity, α, deepens toward the shelf edge, so that the coresite was never isolated from the open Black Sea. Fourteen radiocarbon dates indicate sedimentation from ∼9.3ka to the present, with only one hiatus at ∼270cm depth spanning ∼4.5–2.5ka. Three units are present in the core: Unit A (0–270cm)=burrowed mud with laminated silt beds and mollusc shells of Mediterranean affinity (accumulation rate ∼125cm/ky); Unit B (270–525cm)=silty mud with shelly interbeds containing Truncatella subcylindrica, Mytilus galloprovincialis, Parvicardium exiguum, Rissoa spp. and Modiolula phaseolina (rate ∼85cm/ky); Unit C (525–950cm)=burrowed silty mud with graded beds of silt and fine sand, and shells of T. subcylindrica, P. exiguum and Dreissena polymorpha (rate ∼360cm/ky). Unit C developed below storm wave base at a time when proponents of a catastrophic flood in the Black Sea claim that the shelf was subaerially exposed. Clearly it was not. Ostracoda of Caspian affinity indicate ∼5‰ salinity until ∼7.5ka. Dinocysts and foraminifera confirm a low but rising salinity after ∼8.6ka. An increase of δ 34S from ∼5–30‰ through 8.4–7.6ka is attributed to a first pulse of sulfate-rich Aegean water into an already high Black Sea, after which this sulfate was quantitatively precipitated as sulfide. δ 34S then dropped at ∼8ka to ∼−20‰ as dysoxia and water-column stratification were established because of the initiation of two-way flow through the Bosphorus. Earlier water exchange with the Mediterranean was likely impeded by strong Black Sea outflow which prevented easy access of the Aegean water mass. [Copyright &y& Elsevier]

In a recent (November 2007) paper, it was reported that a 1.4 m increase in sea level rise accompanied the collapse of the Laurentide Ice Sheet, and the resulting discharge of floodwater from 8.4-8.2 cal ka BP drowned a subaerially exposed Black Sea shelf with seawater. The consequence of this hypothetical catastrophic flooding was that early Neolithic farmers had to flee from the region to higher ground in Europe and Russia, thus ending cultural development in the Pontic region for several millennia. In contrast, our paleoenvironmental data collected from sediment cores on the SW Black Sea Shelf and the Marmara Sea show that the Black Sea was already connected to the World's Oceans by 9.5 cal ka BP, and central shelf was flooded by brackish water to a depth of ca. 20 m by 8.6 cal ka BP or earlier. Our data show a slow two-step reconnection of the Black and Mediterranean seas in the early Holocene, at which time the climate was relatively warm and wet, not cold and dry as required for drawdown and isolation of a Black Sea lake. Our palynological data also show that there is no evidence for either a catastrophic flood around 8.4-8.2 cal ka BP, or for sustained agriculture near the Black Sea before the Bronze Age, ca. 6 cal Ka BP. Furthermore, our paleoenvironmental reconstruction is consistent with the available archaeological evidence showing a steady early Holocene migration of agricultural societies into the Mediterranean and Europe westwards from centers in the Middle East. [ABSTRACT FROM AUTHOR]

Abstract: Reconstruction of salinity in the Holocene Black Sea has been an ongoing debate over the past four decades. Here we calibrate summer surface water salinity in the Black Sea, Sea of Azov and Caspian Sea with the process length of the dinoflagellate cyst Lingulodinium machaerophorum. We then apply this calibration to make a regional reconstruction of paleosalinity in the Black Sea, calculated by averaging out process length variation observed at four core sites from the Black Sea with high sedimentation rates and dated by multiple mollusk shell ages. Results show a very gradual change of salinity from ∼14 ± 0.91 psu around 9.9 cal ka BP to a minimum ∼12.3 ± 0.91 psu around 8.5 cal ka BP, reaching current salinities of ∼17.1 ± 0.91 psu around 4.1 cal ka BP. The resolution of our sampling is about 250 years, and it fails to reveal a catastrophic salinization event at ∼9.14 cal ka BP advocated by other researchers. The dinoflagellate cyst salinity-proxy does not record large Holocene salinity fluctuations, and after early Holocene freshening, it shows correspondence to the regional sea-level curve of derived from . [Copyright &y& Elsevier]

Abstract: An exceptionally high-resolution and species-rich dinoflagellate cyst record from core M02-45 collected from the southwestern Black Sea shelf provides strong evidence of a gradual reconnection between the Black (BS) and Mediterranean (MS) seas at the beginning of the Holocene. Two main assemblages, one dominated by brackish species, Spiniferites cruciformis and Pyxidinopsis psilata, and freshwater algae, and a subsequent one, characterised by euryhaline species (Lingulodinium machaerophorum, Brigantedinium spp., Protoperidinium ponticum), document a progressive change in sea-surface conditions from low saline (∼7–12psu) to present-day conditions. A first major pulse of marine waters is recorded at around 8.46ka BP, with a maximum of L. machaerophorum. The occurrence of this species from the bottom of the core, dated at 9.3ka BP, supports the hypothesis that water levels were already high on the southwestern shelf by that time. Fully present-day conditions are recorded at around 5.6ka BP, when brackish species and morphotypes of S. belerius, S. bentorii and L. machaerophorum disappeared. Arrivals of Mediterranean species (Operculodinium centrocarpum and S. mirabilis) are observed simultaneously in the southwest and southeast region of the BS at around 7ka BP. Despite a different protocol for palynomorph preparation and presentation of data, previous studies from the northern shelf also document the arrival of euryhaline species at 7ka BP, and marine influence prior to that time. The history of harmful algal blooms (HABs) shows a correlation with warmer mid-Holocene temperatures, followed by a succession of introductions possibly associated with early Greek exploration, then merchant shipping. [Copyright &y& Elsevier]