Organic-rich sedimentary units called sapropels have formed repeatedly in the eastern Mediterranean Sea, in response to variations of solar radiation. Sapropel formation is due to a change either in the flux of organic matter to the sea floor from productivity changes or in preservation by bottom-water oxygen levels. However, the relative importance of surface-ocean productivity versus deep-water preservation for the formation of these organic-rich shale beds is still being debated, and conflicting interpretations are often invoked. Here we analyse at high resolution the differences in the composition of the most recent sapropel, S1, in a suite of cores covering the entire eastern Mediterranean basin. We demonstrate that during the 4,000 years of sapropel formation, surface-water salinity was reduced and the deep eastern Mediterranean Sea, below 1,800 m depth, was devoid of oxygen. This resulted in the preferential basin-wide preservation of sapropel S1 with different characteristics above and below 1,800 m depth as a result of different redox conditions. We conclude that climate-induced stratification of the ocean may therefore contribute to enhanced preservation of organic matter in sapropels and potentially also in black shales. © 2008 Macmillan Publishers Limited.

De Lange, G., Thomson, J., Reitz, A., Slomp, C., Speranza, M., Erba, E., et al. (2008). Syncronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel. NATURE GEOSCIENCE, 1(9), 606-610 [10.1038/ngeo283].

Syncronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel

CORSELLI, CESARE
2008

Abstract

Organic-rich sedimentary units called sapropels have formed repeatedly in the eastern Mediterranean Sea, in response to variations of solar radiation. Sapropel formation is due to a change either in the flux of organic matter to the sea floor from productivity changes or in preservation by bottom-water oxygen levels. However, the relative importance of surface-ocean productivity versus deep-water preservation for the formation of these organic-rich shale beds is still being debated, and conflicting interpretations are often invoked. Here we analyse at high resolution the differences in the composition of the most recent sapropel, S1, in a suite of cores covering the entire eastern Mediterranean basin. We demonstrate that during the 4,000 years of sapropel formation, surface-water salinity was reduced and the deep eastern Mediterranean Sea, below 1,800 m depth, was devoid of oxygen. This resulted in the preferential basin-wide preservation of sapropel S1 with different characteristics above and below 1,800 m depth as a result of different redox conditions. We conclude that climate-induced stratification of the ocean may therefore contribute to enhanced preservation of organic matter in sapropels and potentially also in black shales. © 2008 Macmillan Publishers Limited.
Articolo in rivista - Articolo scientifico
Paleoceanography, Mediterranean Sea
English
17-ago-2008
1
9
606
610
none
De Lange, G., Thomson, J., Reitz, A., Slomp, C., Speranza, M., Erba, E., et al. (2008). Syncronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel. NATURE GEOSCIENCE, 1(9), 606-610 [10.1038/ngeo283].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/9783
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