DOI: 10.1016/j.palaeo.2012.12.022
论文题名: Interaction of the South American Monsoon System and the Southern Westerly Wind Belt during the last 14kyr
作者: Razik S. ; Chiessi C.M. ; Romero O.E. ; von Dobeneck T.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 374 起始页码: 28
结束页码: 40
语种: 英语
英文关键词: Brazil-Malvinas Confluence
; Marine sediments
; Multi-proxy study
; South American Monsoon
; Southern Westerlies
; Subtropical Shelf Front
; Western South Atlantic
英文摘要: 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 Niño 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. © 2012 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69796
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geosciences, University of Bremen, Klagenfurter Straße, D-28359 Bremen, Germany; MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Straße, D-28359 Bremen, Germany; School of Arts, Sciences and Humanities, University of São Paulo, Av. Arlindo Bettio 1000, CEP03828-000 São Paulo, SP, Brazil; Instituto Andaluz de Ciencias de la Tierra, Universidad de Granada, Av. de las Palmeras 4, 18100 Armilla-Granada, Spain
Recommended Citation:
Razik S.,Chiessi C.M.,Romero O.E.,et al. Interaction of the South American Monsoon System and the Southern Westerly Wind Belt during the last 14kyr[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,374