DOI: 10.1016/j.palaeo.2014.01.001
论文题名: Paleoceanographic reconstruction of the western equatorial Atlantic during the last 40 kyr
作者: Santos T.P. ; Belem A.L. ; Barbosa C.F. ; Dokken T. ; Albuquerque A.L.S.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 415 起始页码: 14
结束页码: 20
语种: 英语
英文关键词: Atlantic Meridional Overturning Circulation
; Oxygen stable isotopes
; Planktonic foraminiferal assemblage
; Sea surface salinity
; Sea surface temperature
英文摘要: The North Brazil Current in the western equatorial Atlantic is the main route for poleward heat transfer and therefore is a key component of the climate system. To understand the parameters that influence this region, we present a paleoceanographic reconstruction of the last 40kyr based on study of sediment core MC 10/3. This reconstruction is based on: i) the oxygen isotope composition of the planktonic foraminifer Globigerinoides ruber (white); ii) census counts of the planktonic foraminifera assemblage to estimate sea surface temperature (SST) via the Modern Analogue Technique (SSTMAT) and to deduce characteristics of the water column; and iii) values of δ18Oivc-sw (a proxy for sea surface salinity (SSS)). The oxygen isotope composition of G. ruber showed a strong shift of greater than 1% after 21calkyrBP. Such a change can be attributed mainly to a salinity reduction of two units, as well as a slight SST increase (~1°C), between 21 and 17.5kyrBP. This change may be related to a southward displacement of the Intertropical Convergence Zone (ITCZ) and its belt of convective activity, which would have increased precipitation over the region and diminished surface salinity. The structure of the planktonic foraminiferal assemblage also indicates such conditions. The productive/thermocline-dwelling Globigerinita glutinata showed higher abundance prior to 21calkyrBP. Other productive/deep-dwellers, i.e., Neogloboquadrina dutertrei, Globorotalia truncatulinoides (left- and right-coiling) and Globorotalia inflata, were slightly more abundant prior to 21calkyrBP and became less frequent with the development of low-salinity surface water that created more stratified and oligotrophic conditions in the water column. However, the warm/oligotrophic surface-dwellers (G. ruber, Globigerinoides sacculifer and Globigerinella siphonifera) became more abundant after 21calkyrBP. The species Globorotalia menardii was nearly absent during the Last Glacial Maximum (LGM), and its growth in abundance, mainly after 17.5calkyrBP, may indicate the resumption of the Agulhas leakage, which would have reached the study area via the South Equatorial Current (SEC). The return of high salinity values synchronous with the G. menardii increase also denotes the influence of Agulhas leakage into the western equatorial Atlantic. © 2014 Elsevier B.V. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69165
Appears in Collections: 过去全球变化的重建
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作者单位: Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro de São João Batista, s/no., Niterói, Rio de Janeiro, CEP, Brazil; Bjerknes Centre for Climate Research, Allégaten 55, Bergen, Norway
Recommended Citation:
Santos T.P.,Belem A.L.,Barbosa C.F.,et al. Paleoceanographic reconstruction of the western equatorial Atlantic during the last 40 kyr[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,415