A 600,000‐year record of Antarctic Bottom Water activity inferred from sediment textures and structures in a sediment core from the Southern Brazil Basin

Massé, Laurent; Faugères, Jean-Claude; Bernat, M.; Pujos, A.; Mézerais, Marie-Laure

doi:10.1029/94pa01442

Cited by 28 publications

(10 citation statements)

References 39 publications

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“…This trend is consistent with low resolution grain size records from the South Atlantic that suggest orbital scale variability in SSW flow speeds with increased vigor occurring during glacial periods (Ellwood and Ledbetter, 1977;Ledbetter, 1979;Allison and Ledbetter, 1982;Ledbetter and Balsam, 1985;Haskell et al, 1991;Ledbetter and Bork, 1993). Moreover, sedimentological evidence from the Southern Brazilian Basin (Masse et al, 1994) N4200 m water depth suggests increased SSW vigor during cold North Atlantic intervals, similar to the increase in SSW flow speeds observed during both the H1 and YD intervals at 28GGC. Together these observations are suggestive of large-scale oscillations in both the NSW and SSW vigor, coincident with regional climate variations throughout the deglaciation, potentially supporting a 'seesaw' in the deepwater production between the North Atlantic and Southern Oceans (Crowley, 1992;Broecker, 1998).…”

Section: Resultssupporting

confidence: 87%

See 1 more Smart Citation

Deep water flow speed and surface ocean changes in the subtropical North Atlantic during the last deglaciation

Hall¹,

Evans²,

Thornalley³

2011

Global and Planetary Change

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Section: Resultssupporting

confidence: 87%

“…The dynamics of this SSW also remain poorly understood with some evidence hinting at vigorous flow during cool periods (e.g. Masse et al, 1994).…”

Section: Introductionmentioning

confidence: 98%

Deep water flow speed and surface ocean changes in the subtropical North Atlantic during the last deglaciation

Hall¹,

Evans²,

Thornalley³

2011

Global and Planetary Change

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“…Similar observations of vigorous SSW flow have been made during the LGM and HS1 from the Northwest Atlantic [ Evans and Hall , ; Hall et al ., ] although the picture from the Southwest Atlantic during glacial periods is less clear [e.g., Ledbetter and Johnson , ; Ledbetter , ; Masse et al ., ]. More vigorous inflow of SSW has been reported during glacial intervals into the Southwest Pacific [ Hall et al ., ].…”

Section: Resultsmentioning

confidence: 99%

Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions

et al. 2013

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[1] Six Ocean Drilling Program (ODP) sites, in the Northwest Atlantic have been used to investigate kinematic and chemical changes in the "Western Boundary Undercurrent" (WBUC) during the development of full glacial conditions across the Marine Isotope Stage 5a/ 4 boundary (~70,000 years ago). Sortable silt mean grain size SS ð Þ measurements are employed to examine changes in near bottom flow speeds, together with carbon isotopes measured in benthic foraminifera and % planktic foraminiferal fragmentation as proxies for changes in water-mass chemistry. A depth transect of cores, spanning 1.8-4.6 km depth, allows changes in both the strength and depth of the WBUC to be constrained across millennial scale events.SS measurements reveal that the flow speed structure of the WBUC during warm intervals ("interstadials") was comparable to modern (Holocene) conditions. However, significant differences are observed during cold intervals, with higher relative flow speeds inferred for the shallow component of the WBUC (~2 km depth) during all cold "stadial" intervals (including Heinrich Stadial 6), and a substantial weakening of the deep component (~3-4 km) during full glacial conditions. Our results therefore reveal that the onset of full glacial conditions was associated with a regime shift to a shallower mode of circulation (involving Glacial North Atlantic Intermediate Water) that was quantitatively distinct from preceding cold stadial events. Furthermore, our chemical proxy data show that the physical response of the WBUC during the last glacial inception was probably coupled to basin-wide changes in the water-mass composition of the deep Northwest Atlantic.

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“…Consequently, the Rio Grande Rise and the deep 21" 1 4 ' s 18" 5 3 ' s 18" 5 0 ' s 25" 30,64'S 26" 27,86'S 27" 37,06'S 22" 14,35'S Longitude 39" 04' W 37" 50' W 37" 46' W 39" 29,70' W 37" 53,64' W 31" 37,16' W 37" 59,97' W Depth (m) Length (cm) 2420 1458 1275 1530 2310 530 3484 793 4265 1507 4370 1561 4567 1281 southern Brazil Basin, swept by AABW and almost free of proximal continental supply, are key zones to study the imprint of deep-sea currents on the sedimentation (e.g. Johnson et al, 1976Johnson et al, , 1977Ledbetter, 1979;Curry & Lohmann, 1982;Schmitz & Hogg, 1983;Hogg et al, 1982;Price et al, 1985;Richardson et al, 1987;MBzerais, 1991;MassB, 1993;MBzerais et al, 1993;Masse et al, 1994). However, the characteristics of Quaternary deposits in the southern Brazil Basin itself are still poorly known.…”

Section: Introductionmentioning

confidence: 99%

Sediment flux distribution in the Southern Brazil Basin during the late Quaternary: the role of deep‐sea currents

et al. 1996

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Detailed sedimentological and stratigraphic analyses were carried out on seven Kullenberg cores collected across the Brazilian continental margin during the French cruises Byblos and Apsara III, in order to highlight the factors controlling the sediment flux distribution in the Southern Brazil Basin during the late Quaternary. On the continental slope and upper continental rise above 3000 m depth, sediment fluxes are important and highly variable (4·2–14·2 g cm−2 10−3 yr). The sediments show a pelagic or turbiditic character, depending on the width of the shelf and proximity of canyons. The material is characterized by high kaolinite contents, and originates from the coastal rivers draining the South American continent north of Rio de Janeiro. On the middle continental rise between 3000 and 4000 m depth, sediment fluxes are the lowest observed in the area (0·9 g cm−2 10−3 yr), because terrigenous input is trapped at shallower depths on the São Paulo Plateau. Pelagic settling is the dominant process. In the deep domains, below 4000 m depth, contouritic accumulations are developed on the path of the northwards moving Antarctic bottom water (AABW) currents. The deposits consist of fine‐grained silty‐clayey muds with very low carbonate contents. The sediment fluxes (1·45 g cm−2 10−3 yr) are higher than on the middle continental rise, as a consequence of fine‐grained terrigenous supply derived from higher latitudes (Argentine Basin and Southern Ocean), and transported in the basin through the Vema Channel by the AABW currents. This material is characterized by high smectite and chlorite contents. These data reveal large sediment flux variations which are linked to distinct depth‐related domains. Such a distribution is the consequence of the presence of two available sources of terrigenous sediments: (1) the Brazilian continental areas with a downslope material transport and a sediment distribution controlled by the morphology of the margin, and (2) the Argentine Basin with an alongslope material transport by deep‐sea currents which dominate the sedimentation in the abyssal domains.

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A 600,000‐year record of Antarctic Bottom Water activity inferred from sediment textures and structures in a sediment core from the Southern Brazil Basin

Cited by 28 publications

References 39 publications

Deep water flow speed and surface ocean changes in the subtropical North Atlantic during the last deglaciation

Deep water flow speed and surface ocean changes in the subtropical North Atlantic during the last deglaciation

Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions

Sediment flux distribution in the Southern Brazil Basin during the late Quaternary: the role of deep‐sea currents

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