A highly productive Subarctic Atlantic during the Last Interglacial and the role of diatoms

Romero, O. E and Swann, G. E. A. and Hodell, D. A. and Helmke, P. and Rey, D. and Rubio, B. (2011) A highly productive Subarctic Atlantic during the Last Interglacial and the role of diatoms. Geology, 39 (11). pp. 1015-1018. DOI 10.1130/G32454.1

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Abstract

The Last Interglacial (LIG), corresponding to Marine Isotope Stage (MIS) 5e, provides a reference of interglacial climate variability in the absence of anthropogenic forcing. Using an expanded section of the LIG gained at Integrated Ocean Drilling Program Site U1304 in the Subarctic Atlantic, we demonstrate that the early MIS 5e was marked by oceanographic conditions conducive for high diatom production and accumulation. The appearance of diatom-dominated laminated oozes ∼3 k.y. after the beginning of MIS 5e at ca. 125 ka coincides with a shift to higher δ30Sidiat values together with the dominance of Thalassiothrix longissima, indicative of increased nutrient availability and silicic acid utilization in surface waters. Though the Subarctic Front provided the physical conditions for high diatom production and deposition, these processes alone are insufficient to explain the high rates of siliceous productivity and the formation of diatomaceous sediments. Instead, the additional presence of an increased nutrient pool provided by Subantarctic Mode Water played the decisive role in initiating and sustaining diatom production. The high diatom productivity and the occurrence of diatomaceous sediments in the late Quaternary challenge the current hypothesis of a silica-depleted North Atlantic during the LIG.

Item Type: Article
Uncontrolled Keywords: 2011AREP; IA63;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Geology
Volume: 39
Page Range: pp. 1015-1018
Identification Number: 10.1130/G32454.1
Depositing User: Sarah Humbert
Date Deposited: 07 Feb 2012 17:21
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2362

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