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Nd isotopic compositions of eastern Mediterranean sediments: tracers of the Nile influence during sapropel S1 formation?

Nd isotopic compositions of eastern Mediterranean sediments: tracers of the Nile influence during sapropel S1 formation?
Nd isotopic compositions of eastern Mediterranean sediments: tracers of the Nile influence during sapropel S1 formation?
Nd isotopic composition of Eastern Mediterranean sediments are used to investigate the influence of Nile flux variations during the formation of the youngest sapropel S1. Four box cores located on an east–west transect (around 35°N) at increasing distance from the Nile source were studied. Nd(0) signatures were measured in the lithogenic (alumino-silicate residue) fraction and the authigenic/biogenic (carbonates, organic matter and Fe, Mn oxyhydroxides) fraction of the sediment after 1 M HCl leaching. The Nd(0) profiles of the residual fraction show more radiogenic values in the sapropel layers than in the adjacent sediments. These profiles follow the Gaussian-shaped Ba/Al profile shape which defines S1. The Nd(0) variations can be related to changes in the proportions of two continental sources of particulate material: Nile particles and Saharan aerosols. A simple mixing model reveals that the contribution of Nile particulates to the sediments increases relative to Saharan aerosols during sapropel formation, indicating a higher Nile discharge and a decrease in eolian input at that time. For the cores located closest to the Nile fan, the Nd(0) signatures of the leachable fraction are always higher in the sapropel layer (?5 to ?4) than in the adjacent sediments (~?6). The sapropel layer Nd(0) values increase with decreasing distance to the Nile towards values close to the Nile particulates. All the results obtained on the leachable fraction point towards a massive input of Nile freshwater during S1 deposition.
MEDITERRANEAN SEA, R NILE, SEDIMENTS, SAPROPELS
0025-3227
45-62
Freydier, R.
9ed2b91f-c359-4546-87f3-702d88e7515e
Michard, A.
61336132-6ea5-4b2a-bbe7-1f387eb8f4b5
De Lange, G.
733ebfad-ed82-4770-80cc-fd12fb87850c
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
Freydier, R.
9ed2b91f-c359-4546-87f3-702d88e7515e
Michard, A.
61336132-6ea5-4b2a-bbe7-1f387eb8f4b5
De Lange, G.
733ebfad-ed82-4770-80cc-fd12fb87850c
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b

Freydier, R., Michard, A., De Lange, G. and Thomson, J. (2001) Nd isotopic compositions of eastern Mediterranean sediments: tracers of the Nile influence during sapropel S1 formation? Marine Geology, 177 (1/2), 45-62. (doi:10.1016/S0025-3227(01)00123-2).

Record type: Article

Abstract

Nd isotopic composition of Eastern Mediterranean sediments are used to investigate the influence of Nile flux variations during the formation of the youngest sapropel S1. Four box cores located on an east–west transect (around 35°N) at increasing distance from the Nile source were studied. Nd(0) signatures were measured in the lithogenic (alumino-silicate residue) fraction and the authigenic/biogenic (carbonates, organic matter and Fe, Mn oxyhydroxides) fraction of the sediment after 1 M HCl leaching. The Nd(0) profiles of the residual fraction show more radiogenic values in the sapropel layers than in the adjacent sediments. These profiles follow the Gaussian-shaped Ba/Al profile shape which defines S1. The Nd(0) variations can be related to changes in the proportions of two continental sources of particulate material: Nile particles and Saharan aerosols. A simple mixing model reveals that the contribution of Nile particulates to the sediments increases relative to Saharan aerosols during sapropel formation, indicating a higher Nile discharge and a decrease in eolian input at that time. For the cores located closest to the Nile fan, the Nd(0) signatures of the leachable fraction are always higher in the sapropel layer (?5 to ?4) than in the adjacent sediments (~?6). The sapropel layer Nd(0) values increase with decreasing distance to the Nile towards values close to the Nile particulates. All the results obtained on the leachable fraction point towards a massive input of Nile freshwater during S1 deposition.

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Published date: 2001
Keywords: MEDITERRANEAN SEA, R NILE, SEDIMENTS, SAPROPELS

Identifiers

Local EPrints ID: 7946
URI: http://eprints.soton.ac.uk/id/eprint/7946
ISSN: 0025-3227
PURE UUID: c29e273d-fdac-45b5-ab81-8035aa1374bb

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Date deposited: 10 Aug 2004
Last modified: 15 Mar 2024 04:50

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Contributors

Author: R. Freydier
Author: A. Michard
Author: G. De Lange
Author: J. Thomson

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