82
G. Lericolais
the isolated Black Sea is of interest in the ongoing discussion about the impacts of the
last reconnection. Accurate salinity estimation is also desired to better understand
paleo-environmental proxies of the isolated Black Sea since currently there is no
analogue of this ancient giant lake. Soulet et al. (2010) using an advection-diffusion
model for pore water collected into Black Sea cores during ASSEMBLAGE cruise
compared different scenario models of bottom water chloride and δ
18 O variations and
simulated the impact of a catastrophic reconnection and a smoother reconnection.
The comparison suggests that the glacial Black Sea was a homogeneous freshwater
lake (with a δ
18 O of ∼ − 10 % and a salinity of ∼ 1 psu). Modern hydrologic conditions would only have been reached at ∼ 2,000 years BP, concomitant with the
onset of coccolith-rich thin layers that characterize modern basin sediments (Giunta
et al. 2007). This recent results obtained from pore water analyses precise the results
obtained by Manheim and Chan (1975) and confirm that the Black Sea was a fresh
water lake prior to its reconnection with the Marmara Sea.
6.4 Discussion and Conclusion
The assessment of the north-western part of the Black Sea sedimentary systems
from the continental shelf and slope down to the deep sea zone provided by the
ASSEMBLAGE European Project bring important highlights to the debate regarding
the precise timing and amplitude of the reconnection between the Black Sea and the
Mediterranean Sea about 9,000 years ago. The results obtained from geophysical data
and core analyses provide a solid record of the Black Sea Last Glacial Maximum
(LGM) water level fluctuations and shed new light on the controversy concerning the
Black Sea water level fluctuation since the Last Glacial Maximum. ASSEMBLAGE
project has attempted to assess the last sea-level rise in the Black Sea and provide
scenarios quantifying the processes governing the transition of Black Sea system from
a low-salinity lake to a marine state while addressing the variability in this system.
One important fact obtained by this extensive mapping of the western Black
Sea shelf is the evidence of a water regression evidenced by the forced regression
features (Lericolais et al. 2009) which took place during the PreBoreal period. In
a recent paper (Lericolais et al. 2010) propose a scenario for the transition of the
Black Sea system from a lacustrine to a marine environment. Six major observations
have documented this Black Sea behaviour: (1) Existence of two lowstand wedges
one dated from the LGM and covered by a second one dated from 11,000 year
BP to 8,000 year BP and located at a water depth ranging from − 100 to − 120 m;
(2) a Danube prodelta built up at − 40 m after the post LGM melt water pulses
was also documented; (3) a set of meandering river channels capped by a regional
unconformity and extending seaward across the Romanian shelf to the vicinity of
the − 100 m isobath was recognized; (4) evidence of submerged shorelines with
wave-cut terraces and coastal dunes, or delta mouth bars at depths between − 80 to
− 100 m, below Holocene Bosporus and Dardanelles Strait outlet sill to the global
ocean; (5) observation on the western part of the Black Sea continental shelf of a
G. Lericolais
the isolated Black Sea is of interest in the ongoing discussion about the impacts of the
last reconnection. Accurate salinity estimation is also desired to better understand
paleo-environmental proxies of the isolated Black Sea since currently there is no
analogue of this ancient giant lake. Soulet et al. (2010) using an advection-diffusion
model for pore water collected into Black Sea cores during ASSEMBLAGE cruise
compared different scenario models of bottom water chloride and δ
18 O variations and
simulated the impact of a catastrophic reconnection and a smoother reconnection.
The comparison suggests that the glacial Black Sea was a homogeneous freshwater
lake (with a δ
18 O of ∼ − 10 % and a salinity of ∼ 1 psu). Modern hydrologic conditions would only have been reached at ∼ 2,000 years BP, concomitant with the
onset of coccolith-rich thin layers that characterize modern basin sediments (Giunta
et al. 2007). This recent results obtained from pore water analyses precise the results
obtained by Manheim and Chan (1975) and confirm that the Black Sea was a fresh
water lake prior to its reconnection with the Marmara Sea.
6.4 Discussion and Conclusion
The assessment of the north-western part of the Black Sea sedimentary systems
from the continental shelf and slope down to the deep sea zone provided by the
ASSEMBLAGE European Project bring important highlights to the debate regarding
the precise timing and amplitude of the reconnection between the Black Sea and the
Mediterranean Sea about 9,000 years ago. The results obtained from geophysical data
and core analyses provide a solid record of the Black Sea Last Glacial Maximum
(LGM) water level fluctuations and shed new light on the controversy concerning the
Black Sea water level fluctuation since the Last Glacial Maximum. ASSEMBLAGE
project has attempted to assess the last sea-level rise in the Black Sea and provide
scenarios quantifying the processes governing the transition of Black Sea system from
a low-salinity lake to a marine state while addressing the variability in this system.
One important fact obtained by this extensive mapping of the western Black
Sea shelf is the evidence of a water regression evidenced by the forced regression
features (Lericolais et al. 2009) which took place during the PreBoreal period. In
a recent paper (Lericolais et al. 2010) propose a scenario for the transition of the
Black Sea system from a lacustrine to a marine environment. Six major observations
have documented this Black Sea behaviour: (1) Existence of two lowstand wedges
one dated from the LGM and covered by a second one dated from 11,000 year
BP to 8,000 year BP and located at a water depth ranging from − 100 to − 120 m;
(2) a Danube prodelta built up at − 40 m after the post LGM melt water pulses
was also documented; (3) a set of meandering river channels capped by a regional
unconformity and extending seaward across the Romanian shelf to the vicinity of
the − 100 m isobath was recognized; (4) evidence of submerged shorelines with
wave-cut terraces and coastal dunes, or delta mouth bars at depths between − 80 to
− 100 m, below Holocene Bosporus and Dardanelles Strait outlet sill to the global
ocean; (5) observation on the western part of the Black Sea continental shelf of a