Temporal stability and origin of chemoclines in the deep hypersaline anoxic Urania basin

Submarine brine lakes feature sharp and persistent concentration gradients between seawater and brine, though these should be smoothed out by free diffusion in open ocean settings. The anoxic Urania basin of the eastern Mediterranean contains an ultrasulfidic, hypersaline brine of Messinian origin a...

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Bibliographic Details
Published in:Geophysical research letters 2015-06, Vol.42 (12), p.4888-4895
Main Authors: Goldhammer, Tobias, Schwärzle, Andreas, Aiello, Ivano W., Zabel, Matthias
Format: Article
Language:English
Subjects:
Anoxia
Basins
Brines
Cellular convection
chemoclines
Communities
Concentration gradient
Convection
deep hypersaline basins
Density stratification
Diffusion
Dye dispersion
Earthquakes
Fluid mud
geochemical modeling
Geochemistry
Gradients
Messinian
Microbial activity
Microorganisms
Modelling
Mud
Origins
Saline water
Salt lakes
Salt water
Seawater
Sediment
Sediments
Seismic activity
Seismic stability
Solute transport
Solutes
Stratification
suspended sediment
Suspended sediments
Thermal convection
Transport
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Summary:Submarine brine lakes feature sharp and persistent concentration gradients between seawater and brine, though these should be smoothed out by free diffusion in open ocean settings. The anoxic Urania basin of the eastern Mediterranean contains an ultrasulfidic, hypersaline brine of Messinian origin above a thick layer of suspended sediments. With a dual modeling approach we reconstruct its contemporary stratification by geochemical solute transport fundamentals and show that thermal convection is required to maintain mixing in the brine and mud layer. The origin of the Urania basin stratification was dated to 1650 years B.P., which may be linked to a major earthquake in the region. The persistence of the chemoclines may be key to the development of diverse and specialized microbial communities. Ongoing thermal convection in the fluid mud layer may have important yet unresolved consequences for sedimentological and geochemical processes, also in similar environments. Key Points A thick layer of fluid mud rests beneath a submarine brine in the Urania basin Thermal gradients cause convection within and sharp chemoclines between layers The brine and mud system may have persisted since a historical earthquake in 365
ISSN:0094-8276
1944-8007
DOI:10.1002/2015GL063758