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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.)

Terrigenous input off northern South America driven by changes in Amazonian climate and the North Brazil Current retroflection during the last 250 ka

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Author(s):
Govin, A. [1] ; Chiessi, C. M. [2] ; Zabel, M. [1] ; Sawakuchi, A. O. [3] ; Heslop, D. [4] ; Hoerner, T. [1] ; Zhang, Y. [1] ; Mulitza, S. [1]
Total Authors: 8
Affiliation:
[1] Univ Bremen, MARUM Ctr Marine Environm Sci, D-28359 Bremen - Germany
[2] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo - Brazil
[3] Univ Sao Paulo, Inst Geosci, Dept Sedimentary & Environm Geol, Sao Paulo - Brazil
[4] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT - Australia
Total Affiliations: 4
Document type: Journal article
Source: Climate of the Past; v. 10, n. 2, p. 843-862, 2014.
Web of Science Citations: 29
Abstract

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 degrees N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9 degrees N, while the core at 12 degrees 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 degrees N) and of Amazon material ({''}%-Amazon{''}, at 12 degrees N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during inter-glacials 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 degrees 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 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. (AU)

FAPESP's process: 11/06609-1 - Provenance, transport and storage of sediments in Amazon rivers
Grantee:André Oliveira Sawakuchi
Support type: Regular Research Grants
FAPESP's process: 12/17517-3 - Response of the Western Atlantic Ocean to changes in the Atlantic meridional overturning circulation: from millennial to seasonal variability
Grantee:Cristiano Mazur Chiessi
Support type: Research Program on Global Climate Change - Young Investigators