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Hydrothermal sediments record changes in deep water oxygen content in the SE Pacific

Hydrothermal sediments record changes in deep water oxygen content in the SE Pacific
Hydrothermal sediments record changes in deep water oxygen content in the SE Pacific
The distribution of redox?sensitive metals in sediments is potentially a proxy for past ocean ventilation and productivity, but deconvolving these two major controls has proved difficult to date. Here we present a 740 kyr long record of trace element concentrations from an archived sediment core collected at ?15°S on the western flank of the East Pacific Rise (EPR) on 1.1 Myr old crust and underlying the largest known hydrothermal plume in the world ocean. The downcore trace element distribution is controlled by a variable diagenetic overprint of the inferred primary hydrothermal plume input. Two main diagenetic processes are operating at this site: redox cycling of transition metals and ferrihydrite to goethite transition during aging. The depth of oxidation in these sediments is controlled by fluctuations in the relative balance of bottom water oxygen and electron donor input (organic matter and hydrothermal sulfides). These fluctuations induce apparent variations in the accumulation of redox?sensitive species with time. Subsurface U and P peaks in glacial age sediments, in this and other published data sets along the southern EPR, indicate that basin?wide changes in deep ocean ventilation, in particular at glacial?interglacial terminations II, III, IV, and V, alter the depth of the oxidation front in the sediments. These basin?wide changes in the deep Pacific have significant implications for carbon partitioning in the ocean?atmosphere system, and the distribution of redox?sensitive metals in ridge crest sediment can be used to reconstruct past ocean conditions at abyssal depths in the absence of alternative proxy records.
0883-8305
PA4226
Mills, R.A.
a664f299-1a34-4b63-9988-1e599b756706
Taylor, S.L.
11e5a6dc-5775-4479-9542-3ee8578cf488
Pälike, H.
b9bf7798-ad8c-479b-8487-dd9a30a61fa5
Thomson, John
ab84c08c-7a63-4129-baa0-2a18ebf8c69a
Mills, R.A.
a664f299-1a34-4b63-9988-1e599b756706
Taylor, S.L.
11e5a6dc-5775-4479-9542-3ee8578cf488
Pälike, H.
b9bf7798-ad8c-479b-8487-dd9a30a61fa5
Thomson, John
ab84c08c-7a63-4129-baa0-2a18ebf8c69a

Mills, R.A., Taylor, S.L., Pälike, H. and Thomson, John (2010) Hydrothermal sediments record changes in deep water oxygen content in the SE Pacific. Paleoceanography, 25, PA4226. (doi:10.1029/2010PA001959).

Record type: Article

Abstract

The distribution of redox?sensitive metals in sediments is potentially a proxy for past ocean ventilation and productivity, but deconvolving these two major controls has proved difficult to date. Here we present a 740 kyr long record of trace element concentrations from an archived sediment core collected at ?15°S on the western flank of the East Pacific Rise (EPR) on 1.1 Myr old crust and underlying the largest known hydrothermal plume in the world ocean. The downcore trace element distribution is controlled by a variable diagenetic overprint of the inferred primary hydrothermal plume input. Two main diagenetic processes are operating at this site: redox cycling of transition metals and ferrihydrite to goethite transition during aging. The depth of oxidation in these sediments is controlled by fluctuations in the relative balance of bottom water oxygen and electron donor input (organic matter and hydrothermal sulfides). These fluctuations induce apparent variations in the accumulation of redox?sensitive species with time. Subsurface U and P peaks in glacial age sediments, in this and other published data sets along the southern EPR, indicate that basin?wide changes in deep ocean ventilation, in particular at glacial?interglacial terminations II, III, IV, and V, alter the depth of the oxidation front in the sediments. These basin?wide changes in the deep Pacific have significant implications for carbon partitioning in the ocean?atmosphere system, and the distribution of redox?sensitive metals in ridge crest sediment can be used to reconstruct past ocean conditions at abyssal depths in the absence of alternative proxy records.

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Published date: 15 December 2010

Identifiers

Local EPrints ID: 166093
URI: http://eprints.soton.ac.uk/id/eprint/166093
ISSN: 0883-8305
PURE UUID: 44c6584c-9cf2-460c-bee6-90b6030b5522
ORCID for R.A. Mills: ORCID iD orcid.org/0000-0002-9811-246X

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Date deposited: 22 Oct 2010 09:13
Last modified: 14 Mar 2024 02:37

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Contributors

Author: R.A. Mills ORCID iD
Author: S.L. Taylor
Author: H. Pälike
Author: John Thomson

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