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Recent turbidite deposition in the eastern Atlantic: early diagnesis and biotic recovery

Recent turbidite deposition in the eastern Atlantic: early diagnesis and biotic recovery
Recent turbidite deposition in the eastern Atlantic: early diagnesis and biotic recovery
An interface core taken in Capbreton canyon shows a succession of sedimentary facies interpreted as classical Bouma turbiditic sequences. Activities of 234Th and 210Pb suggest that the deposition of the most recent turbidite was triggered by the violent storm that affected the Atlantic coast of southern France on the 27th of December 1999, about four months before the sampling of the core. This turbidite allows us to study the ongoing diagenesis of the new sediment layer and of the previous sediment-water interface, which has been buried and only slightly eroded. A study of benthic foraminiferal populations informs us about the rate of benthic ecosystem recovery after such a major ecosystem disturbance event. The composition of the benthic foraminiferal fauna suggests that the benthic ecosystem in Capbreton canyon remains in an early stage of colonization. The rare agglutinant taxon Technitella melo appears to be the first colonizing species. It is suggested that Technitella melo is advantaged by the food-impoverished conditions in the days following turbidite deposition. Almost all of the turbidite layer and the previous oxic sediment-water interface contain reduced dissolved metal species and were anoxic. The buried interface contains Fe- and Mn-oxides inherited from its recent oxic past. The reduction of manganese oxides was in progress at the time of core collection. The reduced Mn remained trapped in the sediment as Mn-containing carbonates. Iron-oxides did not undergo significant reductive dissolution. The top of the newly deposited turbidite formed an oxic layer, which was rapidly enriched in metal-oxides. The enrichment of manganese oxides was mostly due to the oxidation of dissolved Mn2+, which diffused from below. The enrichment of iron oxides is explained both by the oxidation of the upward flux of dissolved Fe2+, and by the input of detrital iron oxide after, or as a result of the turbidite deposition.
TURBIDITES, ATLANTIC OCEAN, DIAGENESIS, THORIUM ISOTOPES, LEAD ISOTOPES, SEDIMENT GRAVITY FLOWS
0022-2402
835-854
Anschutz, P.
fbe3b1f7-caf5-4228-b5b7-8943554f7080
Jorissen, F.J.
5e9da85b-8b77-465e-8816-0ed4acf2da63
Chaillou, G.
316acaf1-da0d-4aa5-b911-85e569a7c2f9
Abu-Zied, R.
bd449980-1df2-43f4-bb04-4888e518b683
Fontanier, C.
8cd62729-bb6f-4b48-a244-6d9ec43a46dd
Anschutz, P.
fbe3b1f7-caf5-4228-b5b7-8943554f7080
Jorissen, F.J.
5e9da85b-8b77-465e-8816-0ed4acf2da63
Chaillou, G.
316acaf1-da0d-4aa5-b911-85e569a7c2f9
Abu-Zied, R.
bd449980-1df2-43f4-bb04-4888e518b683
Fontanier, C.
8cd62729-bb6f-4b48-a244-6d9ec43a46dd

Anschutz, P., Jorissen, F.J., Chaillou, G., Abu-Zied, R. and Fontanier, C. (2002) Recent turbidite deposition in the eastern Atlantic: early diagnesis and biotic recovery. Journal of Marine Research, 60 (6), 835-854. (doi:10.1357/002224002321505156).

Record type: Article

Abstract

An interface core taken in Capbreton canyon shows a succession of sedimentary facies interpreted as classical Bouma turbiditic sequences. Activities of 234Th and 210Pb suggest that the deposition of the most recent turbidite was triggered by the violent storm that affected the Atlantic coast of southern France on the 27th of December 1999, about four months before the sampling of the core. This turbidite allows us to study the ongoing diagenesis of the new sediment layer and of the previous sediment-water interface, which has been buried and only slightly eroded. A study of benthic foraminiferal populations informs us about the rate of benthic ecosystem recovery after such a major ecosystem disturbance event. The composition of the benthic foraminiferal fauna suggests that the benthic ecosystem in Capbreton canyon remains in an early stage of colonization. The rare agglutinant taxon Technitella melo appears to be the first colonizing species. It is suggested that Technitella melo is advantaged by the food-impoverished conditions in the days following turbidite deposition. Almost all of the turbidite layer and the previous oxic sediment-water interface contain reduced dissolved metal species and were anoxic. The buried interface contains Fe- and Mn-oxides inherited from its recent oxic past. The reduction of manganese oxides was in progress at the time of core collection. The reduced Mn remained trapped in the sediment as Mn-containing carbonates. Iron-oxides did not undergo significant reductive dissolution. The top of the newly deposited turbidite formed an oxic layer, which was rapidly enriched in metal-oxides. The enrichment of manganese oxides was mostly due to the oxidation of dissolved Mn2+, which diffused from below. The enrichment of iron oxides is explained both by the oxidation of the upward flux of dissolved Fe2+, and by the input of detrital iron oxide after, or as a result of the turbidite deposition.

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Published date: 2002
Keywords: TURBIDITES, ATLANTIC OCEAN, DIAGENESIS, THORIUM ISOTOPES, LEAD ISOTOPES, SEDIMENT GRAVITY FLOWS

Identifiers

Local EPrints ID: 2161
URI: http://eprints.soton.ac.uk/id/eprint/2161
ISSN: 0022-2402
PURE UUID: cd0d1932-fa73-49d2-b0c5-16abf8788118

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Date deposited: 14 May 2004
Last modified: 15 Jul 2019 19:39

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