High-latitude forcing of diatom productivity in the southern Agulhas Plateau during the past 350 kyr
Romero, O. E. (MARUM Center for Marine Environmental Sciences)
Kim, J. H. (Royal Netherlands Institute for Sea Research.)
Bárcena, M. A. (Universidad de Salamanca. Departamento de Geología)
Hall, Ian R. (Cardiff University. School of Earth and Ocean Sciences)
Zahn, Rainer (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Schneider, R. (Universität Kiel. Institut für Geowissenschaften)

Data:	2015
Resum:	The hydrography of the Indian-Atlantic Ocean gateway has been connected to high-latitude climate dynamics by oceanic and atmospheric teleconnections on orbital and suborbital timescales. A wealth of sedimentary records aiming at reconstructing the late Pleistocene paleoceanography around the southern African continent has been devoted to understanding these linkages. Most of the records are, however, clustered close to the southern South African tip, with comparatively less attention devoted to areas under the direct influence of frontal zones of the Southern Ocean/South Atlantic. Here we present data of the composition and concentration of the diatom assemblage together with bulk biogenic content and the alkenone-based sea surface temperature (SST) variations for the past 350 kyr in the marine sediment core MD02-2588 (approximately 41°S, 26°E) recovered from the southern Agulhas Plateau. Variations in biosiliceous productivity show a varying degree of coupling with Southern Hemisphere paleoclimate records following a glacial-interglacial cyclicity. Ecologically well-constrained groups of diatoms record the glacial-interglacial changes in water masses dynamics, nutrient availability, and stratification of the upper ocean. The good match between the glacial maxima of total diatoms concentration, Chaetoceros spores abundance, and opal content with the maximum seasonal cover of Antarctic ice and the atmospheric dust records points to a dominant Southern Hemisphere forcing of diatom production. Suborbital variability of SST suggests rapid latitudinal migrations of the Subtropical Front and associated water masses over the southern Agulhas Plateau, following millennial contractions and expansions of the subtropical gyres. Warmings of the upper ocean over site MD02-2588 during terminations IV to I occurred earlier than that in the Antarctic Vostok, which is indicative of a Northern Hemisphere lead. Our multiparameter reconstruction highlights how high-latitude atmospheric and hydrographic processes modulated orbital highs and lows in primary production and SST as triggered by northward transport of Si, eolian dust input, and latitudinal migrations of frontal zones.
Ajuts:	European Commission 226600 European Commission 238512
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Agulhas ; SST ; Diatoms ; Fronts ; Silica ; Southern Ocean
Publicat a:	Paleoceanography, Vol. 30, issue 2 (Feb. 2015) , p. 118-132, ISSN 1944-9186

DOI: 10.1002/2014PA002636

15 p, 1022.8 KB

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