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Esin N.V.,RAS Shirshov Institute of Oceanology | Yanko-Hombach V.,Avalon Institute of Applied Science | Yanko-Hombach V.,Odessa I I Mechnikov National University | Kukleva O.N.,RAS Shirshov Institute of Oceanology
Quaternary International | Year: 2010

Although the Late Pleistocene-Holocene fluctuations in the Black Sea have been studied over many years, no overall picture of this difficult natural phenomenon has as yet been developed and described. Moreover, in the literature, many researchers have provided mutually exclusive opinions about many of the processes occurring within this time interval. The variation in conceptualizations about the filling of the Black Sea basin is explained by the following reasons. (1) Fluctuations of sea level in the basin were never properly studied as physical processes under conditions of increased freshwater runoff, change in Bosporus strait depth, increase in World Ocean level, etc. Therefore, some conclusions about sea-level changes were not verified by appropriate calculations and have not been physically substantiated. (2) The study of sea-level fluctuations are conducted according to modern sea depth markers and sediment age, but as the sediment was formed under varying depth conditions, and could have moved relative to modern markers by the agency of various geological processes, it is possible that that every core may give a different level curve. (3) Processes of sedimentation, erosion and redeposition of sediment occurring in the sea have been studied insufficiently. For this reason the same geological material has been interpreted differently by various researchers. Therefore, mathematical modeling of sea-level fluctuations based on various physical laws seems to be of great importance. In this paper, the value and sign for the Black Sea freshwater balance during the Upper Pleistocene-Holocene are discussed. The hypothesis suggests that during the specified period of time, the freshwater balance of the sea was always positive, the sea was filled with water up to the sill mark in the Bosporus strait, and a river flowed into the Sea of Marmara along the strait bottom. In the present paper, geologic evidence of the river flow in the strait during the glacial age and later is presented. Other points of view about the sea's freshwater balance change are considered. A mathematical model of the Black Sea basin filling with freshwater in the Upper Pleistocene-Holocene is suggested. It considers that change in water volume inflowing to the Black Sea to be a result of ablation, neotectonic processes in the strait, bottom erosion, and sediment accumulation. Black Sea level change calculations have shown the following. As a result of repeated increases in river runoff during glacial melting, the level of the Black Sea started to rise from -80 m, probably to -20/-30 m, making, in the process, numerous secondary fluctuations. The reason for this phenomenon was the circumstance that the water volume brought by the rivers could not flow to the Sea of Marmara through the narrow canyon of the Bosporus strait at the time. Therefore, water collected in the sea, raising its level. At approximately 12 ka BP, the World Ocean level rose to the river surface and began to increase its depth. As a result of the increase in strait depth, the accumulated water in the Black Sea flowed out, thereby lowering its level to a mark close to the Ocean level. According to calculations, this occurred ca 11 ka BP. Thereafter, the Black Sea level rose together with the Ocean level. Water within the Sea of Marmara has flowed to the Black Sea since approximately 9 ka BP in the form of a bottom counterflow. With a small time delay, theoretical change in the Black Sea level practically corresponds to data obtained from geological investigations. The theory offered here of fluctuations in Black Sea level is self-sufficient; it explains all processes from the melting of the glaciers, by physical laws and does not demand the application of any additional hypotheses. In the conclusion of this paper, the debatable questions about the Black Sea's possible lowering and the subsequent flooding of the basin are considered. © 2009 Elsevier Ltd and INQUA.

Martin R.E.,University of Delaware | Yanko-Hombach V.,Avalon Institute of Applied Science | Yanko-Hombach V.,Odessa I I Mechnikov National University
Special Paper of the Geological Society of America | Year: 2011

The investigation of rapid sea-level and climate change is critical to understanding the geologic history of the Black Sea and its effect on ancient civilizations of the region and adjacent areas. The current consensus of western scientists is that only local sea-level curves may be constructed because of local-to-regional changes in sedimentation, tectonics, and other factors. Recently, however, I.P. Balabanov published a synoptic sea-level curve for the entire Black Sea that spans the Pleistocene- Holocene transition and the Holocene based on older radiocarbon dates. This curve has been heavily criticized and is viewed skeptically by western workers for the reasons already mentioned as well as the use of questionable methodologies. Here, we examine Balabanov's curve in light of these criticisms by comparing his sea-level curve to other independently derived sea-level and environmental indices. We fi nd that, despite its drawbacks, many of the fluctuations of the Balabanov curve coincide with repeated ocean-atmosphere reorganizations, which involve shifts from cool to warm phases and corresponding changes in the species composition of foraminiferal assemblage ecozones, precipitation, and runoff. We suggest that following the initial invasion of the Black Sea by marine Mediterranean waters during the Pleistocene-Holocene transition, climatic amelioration (warming) following each cool phase of an ocean-atmosphere reorganization resulted in shifting precipitation patterns that produced repeated, rapid freshwater discharges into the Black Sea from surrounding rivers. In this scenario, runoff following each reorganization temporarily altered the species composition of foraminiferal assemblages, as noted in earlier studies. Freshwater discharges during the Holocene were likely lower than those envisioned by Balabanov but may have affected sea level suffi ciently to alter coastal geomorphology and coastal aquifers rapidly, while causing the translocation of settlements from areas where submarine archaeological sites are now situated. Sea-level and climate change during the Pleistocene-Holocene transition may have been similar to that of the Holocene, but greatly amplifi ed. © 2011 The Geological Society of America.

Yanko-Hombach V.,Odessa I I Mechnikov National University | Yanko-Hombach V.,Avalon Institute of Applied Science | Mudie P.J.,Memorial University of Newfoundland | Kadurin S.,Odessa I I Mechnikov National University | Larchenkov E.,Odessa I I Mechnikov National University
Quaternary International | Year: 2014

For two decades, the timing and rate of Holocene marine transgression and the level of the Black Sea prior to the transgression has been the focus of many geological, palaeoecological and archaeological studies. The potential importance of confirming or rejecting the catastrophic flood hypothesis by refining the chronology of the marine transgression and determining the water level of the early Holocene Black Sea (Neoeuxinian) lake is the aim of many ongoing Black Sea palaeoecological studies. In this report we review previous studies and present new data on the early Holocene marine transgression obtained from multidisciplinary studies of several cores from different parts of the Black Sea. Core 342 from the edge of the Dniester paleovalley on NW shelf is particularly important because it provides wood and leaf material from several peat and muddy peat beds, each up to ~10cm thick, inter-layered in a coastal succession with mud, clay, and shell coquina. AMS ages for wood fragments and sedge leaves in the peat layers provide critical new data for calibrating and “re-tuning“ of previously published shell and bulk detrital peat ages. Our multi-disciplinary study of geological material recovered from different shelf areas of the Black Sea refines the chronology of the marine transgression and clarifies conflicting interpretations of the water level and salinity of the Neoeuxinian lake prior to the initial Mediterranean inflow (IMI) and transgression of Mediterranean water in the Holocene, We find that: (1) The level of the Late Neoeuxinan lake prior to the early Holocene Mediterranean transgression stood around -40m bsl but not -100m or more as suggested by advocates of catastrophic/rapid/prominent flooding of the Black Sea by Mediterranean water. (2) At all times, the Neoeuxinan lake was brackish with salinity not less that 7 psu. (3) By 8.9 ka BP, the Black Sea shelf was already submerged by the Mediterranean transgression. An increase in salinity took place over 3600 years, with rate of the marine water incursion being estimated in the order of 0.05cm-1.7cma-1. (4) The combined data set of sedimentological characteristics and microfossil data establish that the Holocene marine transgression was of a gradual, progressive nature in the early Holocene. © 2013 Elsevier Ltd and INQUA.

Esin N.V.,RAS Shirshov Institute of Oceanology | Esin N.I.,RAS Shirshov Institute of Oceanology | Yanko-Hombach V.,Odessa I I Mechnikov National University | Yanko-Hombach V.,Avalon Institute of Applied Science
Quaternary International | Year: 2015

The origin of the bottom counterflow in Bosphorus Strait during the early Holocene, its temporal development and the Black Sea filling by the Mediterranean salt water is discussed in this paper. At 10ka, the depth of the strait was 10m, the velocity of accumulation body growth in the southern part of the strait was 3mm/year, and the velocity of the ocean transgression was 13.5mm/year. The freshwater balance of the Black Sea is accepted as it is now. Based on mathematical modeling the bottom counterflow breakthrough occurred when the depth of the strait was 16.5m, at about 9400 years ago. Before this, salt water penetrated into the Black Sea in the autumn-winter seasons during short periods of time, when the Bosphorus upper stream was absent. The Navier-Stokes equations were used to describe the water circulation. Temporal dependencies of the counterflow depth, water discharge in counterflow and depth of the halocline in the Black Sea was calculated.The halocline reached the depth of 100m about 7200 years ago, and a situation close to present one (the lower Bosphorus flow brought salt into the Black Sea, with the upper stream returning it to the Sea of Marmara. The water discharge in the low water layer was insignificant during the time interval from 9400 to 8400 years ago. Then, it quickly rose to about 700km3/year. © 2015 Elsevier Ltd and INQUA.

Esin N.V.,RAS Shirshov Institute of Oceanology | Yanko-Hombach V.V.,Odessa I I Mechnikov National University | Yanko-Hombach V.V.,Avalon Institute of Applied Science | Esin N.I.,RAS Shirshov Institute of Oceanology
Quaternary International | Year: 2016

A possible mechanism leading to the transformation of the Paratethys seas (i.e., the Sarmatian Sea-Lake, Meotian Sea, Pontian Sea-Lake, etc.) is here proposed. The time period from the formation of the closed Sarmatian Sea-Lake to the present is also considered. It will be shown that the main reason for the collapse of the Sarmatian Sea-Lake into the Black and Caspian seas was development of a canyon that cut through the mountains separating the Black and Mediterranean seas. Later, this canyon was transformed into the Bosporus and the Dardanelles straits. The canyon was formed mainly by erosive activity of a river that had periodically emerged from the Paratethys. Abrasion of the canyon bottom and the related erosional lowering of its level led to gradual drainage of the Paratethys basins. The consequences of the Messinian Salinity Crisis in the Mediterranean Sea contributed to the penetration of salt water into the Paratethys and then to its temporary isolation and transformation into a closed sea-lake. Later, its level rose, and the river was formed again. That river flowed into the Mediterranean Sea, in the process eroding its own bed. During low levels of the World Ocean, the riverbed experienced increased erosion, eventually dropping below high ocean level, at which time the river was flooded by Mediterranean water. This process led to the formation of a corridor linking the seas together; this corridor developed over the course of many glacioeustatic fluctuations in the World Ocean. © 2016 Elsevier Ltd and INQUA.

Esin N.V.,RAS Shirshov Institute of Oceanology | Yanko-Hombach V.,Avalon Institute of Applied Science | Kukleva O.N.,RAS Shirshov Institute of Oceanology | Esin N.I.,Southern Federal University
Doklady Earth Sciences | Year: 2010

A mathematical model describing the Black Sea level change in the Late Pleistocene-Holocene is offered. A theoretical curve for temporal change in the sea level is obtained. It is established that, in the range from 20 to 12 ky BP, the sea level rose to ∼20 m and fluctuated with various amplitudes and periods. In the range from 12 to 11 ky BP during the Bosphorus Strait formation, there was a sea regression by 30-50 meters, and level of the Black Sea dropped to the World Ocean level. Further, it mirrored variation of the ocean level. © 2010 Pleiades Publishing, Ltd.

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