The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

Nace, Trevor; Baker, Paul A.; Dwyer, Gary S.; Silva, Cleverson Guizan; Rigsby, Catherine A.; Burns, Stephen J.; Giosan, Liviu; Otto‐Bliesner, Bette L.; Liu, Zhengyu; Zhu, Jiang

doi:10.1016/j.palaeo.2014.05.030

Cited by 77 publications

(72 citation statements)

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“…et al, 2001). Region D (equatorial west Atlantic Ocean) contains records from the Demerara Rise (9GGC, 25GGC, CDH11, CDH14) (Huang et al, 2014;Lund et al, 2017b) and the Amazon Fan (CDH83, CDH86) (Nace et al, 2014). Region E (SE Pacific Ocean/Chile Margin) contains records from ODP Sites 1233 and 1234 (Mix et al, 2003;Lund et al, 2007).…”

Section: New Long Psv Time Seriesmentioning

confidence: 99%

A New View of Long-Term Geomagnetic Field Secular Variation

Lund

2018

Front. Earth Sci.

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This study carries out a statistical analysis of high-resolution PSV records for the last ∼70 ka from three different regions of the Earth. We consider directional and intensity variability in each region on time scales of 10 3 -10 5 years in order to evaluate long-term PSV. We then compare those results with more traditional long-term PSV statistical studies averaged over ∼10 6 years. Three replicate PSV records from one region (subtropical North Atlantic Ocean) were averaged at overlapping 3 and 9 ka intervals. Variability in both scalar inclination and declination variability and vector angular dispersion are significant and coherent among the three records. The vector dispersion is relatively low for most of the time but contains two relatively narrow intervals (∼30-42 and 60-65 ka) of high dispersion. (Vector dispersion in all records was calculated after removing directions with true excursional VGPs, VGPs < 45 • N). We have carried out a comparable statistical analysis on two other PSV records from other parts of the Earth (Chile margin; Philippines/Indonesia). The results for these three regions are comparable in their overall style of variability. The scalar directional variability from the Philippines/Indonesia is quite different in detail from the other two regions, as might be expected, but the scalar directional variability between the Western Hemisphere regions is remarkably consistent considering their distance from one another. This may be associated with them being on the same longitude swath and having some coherent dynamo activity occurring along that path. Three magnetic field excursions occur in the study interval. All three excursions are associated with the two highest vector dispersion intervals. Paleointensity records from the three regions were subjected to the same statistical analysis as the directions. These records are all coherent in their pattern of variability. The similarity in paleointensity variability on a global scale is expected even though the detailed scalar directional variability is not coherent on a global scale. The pattern of intensity variability is strongly correlated with the pattern of vector dispersion and excursions on a global scale-high (low) intensity is associated with low (high plus excursions) vector dispersion. The fact that regional directional variability is always larger than "normal" during low intensity/excursional intervals, even though the effect of true excursional directions was removed, suggests that we need to reevaluate what field variability was like during low intensity/excursional intervals on a global scale and how/why it was different from today's field (last 10 4 years).

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Section: New Long Psv Time Seriesmentioning

confidence: 99%

A New View of Long-Term Geomagnetic Field Secular Variation

Lund

2018

Front. Earth Sci.

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“…A single sample (-14) shows an indication of an inner shelf environment, presenting the more positive values of both δ 13 C and N/C. The variations of ln(Fe/K) indicate oscillations in the input of illite or kaolinite to the depositional environment and can be used as proxies for changes in local and regional weathering (Ziegler et al 2013, Nace et al 2014, Simon et al 2015. A higher level in K is found in samples -12 and -13 (Fig.…”

Section: Resultsmentioning

confidence: 93%

Evidence of an Marine Isotope Stage 3 transgression at the Baixada Santista, south-eastern Brazilian coast

et al. 2017

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ABSTRACT:In this paper, we present new evidence regarding a Marine Isotope Stage 3 (MIS3) transgression on the south-eastern Brazilian coast (Baixada Santista coastal plain). Data collected from a Standard Penetration Test (SPT) drilling reveal the occurrence of myxohaline sediments between cal BP 45,000 and 41,000. A deeper sequence, which shows a clear transition from terrestrial to a myxohaline environment, was associated with MIS5e. Organic and inorganic proxies have been used to recognize the variations on the terrestrial/myxohaline/marine deposits, as well as to infer about climate and energy of the depositional environment. Environmental change, which could correspond to a sea-level peak or the occurrence of drier conditions, was recognized between 43,000 and 42,000 cal BP. The results reinforce the need for future works on MIS3 variability on the South American Atlantic coast. KEYWORDS:Marine Isotope Stage 3; Late Pleistocene; sea-level. RESUMO: Neste artigo, apresentamos novas evidências sobre a transgressão ocorrida Estágio Isotópico 3 (MIS3) na costa do sudeste do Brasil (Baixada Santista). Dados coletados por meio de um ensaio de penetração em solo (SPT) revelam a ocorrência de sedimentos mixohalinos entre 45.000 e 41.000 anos a.P. Uma sequência mais profunda, que mostra clara transição de ambiente continental para um mixohalino, foi associada ao Estágio Isotópico 5e (MIS5e). Marcadores orgânicos e inorgânicos foram usados para reconhecer as variações dos ambientes ter

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“…Previous studies have correlated pulses of terrigenous input with cold events in the NH off the coast of generally dry northeastern SA Nace et al, 2014). Yet, the 23-7ºS sector of the Brazilian continental margin remains completely void of studies.…”

Section: Introduction / Introduçãomentioning

confidence: 99%

“…Previous works have used Ti/Ca and Fe/Ca ratios to trace changes in terrigenous 323 input of fluvial origin of South American rivers, particularly offshore the semiarid 324 northeastern Brazil, where repeated authors pointed out increases in the terrigenous input 325 during Heinrich events due to southward shifts of the ITCZ 326 Jaeschke et al, 2007;Nace et al, 2014;Zhang et al, 2015). 327…”

mentioning

confidence: 99%

“…384 385 Second, different weathering patterns and sediment transport between densely 386 vegetated tropical eastern SA and the semiarid areas should also be considered. As 387 mentioned above, previous studies that assessed shifts in precipitation and the related 388 changes in Ti/Ca and Fe/Ca were carried out off northeastern Brazil 389 Jaeschke et al, 2007;Nace et al, 2014;Zhang et al, 2015). That 390 area is characterized by semiarid climate (Bsh, Köppen-Geiger climate type, Peel et al,391 2007) which favor a fast response of the terrigenous input to oceanic basins for several 392 reasons.…”

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Climatic evolution of eastern South America during the last deglaciation: a paleoceanographic approach

Catunda¹

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Autorizo a reprodução e divulgação total ou parcial deste trabalho, por qualquer meio convencional ou eletrônico, para fins de estudo e pesquisa, desde que citada a fonte. ii AbstractTo support the current debate and actions to be taken about climatic consequences of anthropogenic release of CO2, a refined understanding about past climatic and oceanographic changes is necessary. The Atlantic Meridional Overturning Circulation (AMOC) plays a fundamental role in the oceanography and climate of the Atlantic realm, directly controlling stratification and distribution of water masses, the amount of heat that is transported by the ocean, and the cycling and storage of chemical species, such as carbon dioxide in the deep sea. The formation and circulation of Antarctic Intermediate Water (AAIW) is an important component of the upper branch of the AMOC, involved in the transport of heat and salt within the Southern Hemisphere subtropical gyre and driving high-low latitude climatic teleconnections. Reconstructing intermediate water properties is, therefore, important for understanding feedbacks within the ocean-climate system. However, information on AAIW evolution remains limited. AMOC oscillations and changes in heat distribution have strong implications for the South American climate, influencing moisture influx availability for the South American Summer Monsoon (SASM), via sea surface temperatures and Intertropical Convergence Zone positioning. Here we reconstruct AAIW isotopic signature during marine isotope stages 2 and 3 (41-12 cal kyr BP) using carbon and oxygen isotopes from benthic foraminifera (Cibicidoides and Uvigerina genera) of a radiocarbon dated marine sediment core (1100m water depth and 20S, off the Brazilian coast). We find that AAIW's physical and chemical properties changed Heinrich stadials 3 and 4, probably as a consequence of AMOC decreased strength during these periods. We also reconstruct Last Glacial Maximum and deglacial (23-12 cal kyr BP) continental conditions over eastern Brazil based on Ti/Ca of our marine sediment core as a proxy for Doce River (draining eastern Brazil) terrigenous input. Most of the rainfall in the Doce River Basin is related to the activity of the SASM. Our Ti/Ca record together with a speleothem  18 O composite from Lapa Sem Fim Cave, also in eastern Brazil, suggests a major decrease in precipitation during the Bølling-Allerød interstadial, likely related to a weakening of the SASM. We further compared our Ti/Ca results with the output of the SYNTRACE run of the CCSM3 fully-coupled climate model with transient forcing for the last deglaciation. Geochemical records and model output show consistent results and suggest that eastern South America experienced the driest period of the whole last deglaciation during the Bølling-Allerød and that this dry spell was likely related to decreased SAMS intensity.Keywords: paleoclimatology, paleoceanography, Quaternary, geochemistry, foraminifera, AMOC, millennial events, precipitation.iii ResumoPara dar suporte ao atual debate so...

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The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

Cited by 77 publications

References 73 publications

A New View of Long-Term Geomagnetic Field Secular Variation

A New View of Long-Term Geomagnetic Field Secular Variation

Evidence of an Marine Isotope Stage 3 transgression at the Baixada Santista, south-eastern Brazilian coast

Climatic evolution of eastern South America during the last deglaciation: a paleoceanographic approach

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