Palaeogeography, Palaeoclimatology, Palaeoecology, Dec 1, 2014, Vol.415, p.28(9)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2013.12.005 Byline: Cristiano M. Chiessi, Stefan Mulitza, Jeroen Groeneveld, Juliana B. Silva, Marilia C. Campos, Marcio H.C. Gurgel Abstract: Our understanding of the centennial-scale variability of the Brazil Current (BC) during the late Holocene is elusive because of the lack of appropriate records. Here we used the Mg/Ca and oxygen isotopic composition of planktonic foraminifera from two marine sediment cores collected at 27[degrees]S and 33[degrees]S off southeastern South America to assess the late Holocene variability in the upper water column of the BC. Our results show in phase fluctuations of up to 3[degrees]C in sea surface temperatures (SST), and 0.8a[degrees] in oxygen isotopic composition of surface sea water, a proxy for relative sea surface salinity (SSS). Time-series analyses of our records indicate a cyclicity with a period of ca. 730yr. We suggest that the observed cyclicity reflects variability in the strength of the BC associated to changes in the Atlantic meridional overturning circulation (AMOC). Positive (negative) SST and SSS anomalies are related to a strong (weak) BC and a weak (strong) AMOC. Moreover, periods of peak strength in the BC occur synchronously to a weak North Brazil Current, negative SST anomalies in the high latitudes of the North Atlantic, and positive (negative) precipitation anomalies over southeastern South America (equatorial Africa), further corroborating our hypothesis. This study shows a tight coupling between the variability of the BC and the high latitudes of the North Atlantic mediated by the AMOC even under late Holocene boundary conditions. Article History: Received 1 August 2013; Revised 29 November 2013; Accepted 4 December 2013
Holocene Paleogeography -- Analysis ; Thermohaline Circulation -- Analysis ; Precipitation (Meteorology) -- Analysis
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