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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Interaction of the South American Monsoon System and the Southern Westerly Wind Belt during the last 14 kyr

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Razik, Sebastian [1] ; Chiessi, Cristiano M. [2] ; Romero, Oscar E. [1] ; von Dobeneck, Tilo [2, 1]
Total Authors: 4
[1] Univ Bremen, Dept Geosci, D-28359 Bremen - Germany
[2] Univ Bremen, MARUM Ctr Marine Environm Sci, D-28359 Bremen - Germany
Total Affiliations: 2
Document type: Journal article
Web of Science Citations: 26

Surface currents and sediment distribution of the SE South American upper continental margin are under the influence of the South American Monsoon System (SAMS) and the Southern Westerly Wind Belt (SWWB). Both climatic systems determine the meridional position of the Subtropical Shelf Front (STSF) and probably also of the Brazil-Malvinas Confluence (BMC). We reconstruct the changing impact of the SAMS and the SWWB on sediment composition at the upper Rio Grande Cone off southern Brazil during the last 14 cal kyr BP combining sedimentological, geochemical, micropaleontological and rock magnetic proxies of marine sediment core GeoB 6211-2. Sharp reciprocal changes in ferri- and paramagnetic mineral content and prominent grain-size shifts give strong clues to systematic source changes and transport modes of these mostly terrigenous sediments. Our interpretations support the assumption that the SAMS over SE South America was weaker than today during most of the Late Glacial and entire Early Holocene, while the SWWB was contracted to more southern latitudes, resembling modern austral summer-like conditions. In consequence, the STSF and the BMC were driven to more southern positions than today's, favoring the deposition of Fe-rich but weakly magnetic La Plata River silts at the Rio Grande Cone. During the Mid Holocene, the northern boundary of the SWWB migrated northward, while the STSF reached its northernmost position of the last 14 cal kyr BP and the BMC most likely arrived at its modern position. This shift enabled the transport of Antarctic diatoms and more strongly magnetic Argentinean shelf sands to the Rio Grande Cone, while sediment contributions from the La Plata River became less important. During the Late Holocene, the modern El Nino Southern Oscillation set in and the SAMS and the austral tradewinds intensified, causing a southward shift of the STSF to its modern position. This reinforced a significant deposition of La Plata River silts at the Rio Grande Cone. These higher magnetic silts with intermediate Fe contents mirror the modern more humid terrestrial climatic conditions over SE South America. (C) 2012 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 11/50394-0 - Variability of the South American monsoon system of the last three millennia integrating lake, speleothem and marine records
Grantee:Francisco William da Cruz Junior
Support type: Research Program on Global Climate Change - Regular Grants
FAPESP's process: 10/09983-9 - Sea surface temperature changes in the western South Atlantic and precipitation variability in southeastern South America since the Last Glacial Maximum
Grantee:Cristiano Mazur Chiessi
Support type: Regular Research Grants