DOI: 10.5194/cp-10-843-2014
Scopus记录号: 2-s2.0-84899534634
论文题名: Terrigenous input off northern South America driven by changes in Amazonian climate and the North Brazil Current retroflection during the last 250 ka
作者: Govin A. ; Chiessi C.M. ; Zabel M. ; Sawakuchi A.O. ; Heslop D. ; Hörner T. ; Zhang Y. ; Mulitza S.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2014
卷: 10, 期: 2 起始页码: 843
结束页码: 862
语种: 英语
Scopus关键词: climate change
; climate variation
; interglacial
; nitrogen
; particulate matter
; plume
; resolution
; sediment core
; speleothem
; suspended sediment
; Amazonas [Brazil]
; Brazil
英文摘要: We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial periods. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. Increased Amazonian rainfall reflects the intensification of the South American monsoon in response to enhanced land-ocean thermal gradient and moisture convergence. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganizations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume. © Author(s) 2014. 资助项目: ARC, Deutsche Forschungsgemeinschaft
; DFG, Deutsche Forschungsgemeinschaft
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49275
Appears in Collections: 气候变化与战略
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Recommended Citation:
Govin A.,Chiessi C.M.,Zabel M.,et al. Terrigenous input off northern South America driven by changes in Amazonian climate and the North Brazil Current retroflection during the last 250 ka[J]. Climate of the Past,2014-01-01,10(2)