Meltwater discharge anomalies in marine isotope stage 3 from a sediment core in the south of Antarctic Polar Front, Drake Passage

2003 ◽  
Vol 7 (1) ◽  
pp. 73-79
Author(s):  
Sung Ho Bae ◽  
Ho Il Yoon ◽  
Byong-Kwon Park ◽  
Yeadong Kim ◽  
Jang Jun Bahk ◽  
...  
Keyword(s):  
Sediment Core ◽  
Drake Passage ◽  
Polar Front ◽  
Marine Isotope Stage ◽  
Antarctic Polar Front ◽  
The South ◽  
Marine Isotope Stage 3

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

2017 ◽  
Vol 47 (4) ◽  
pp. 693-702 ◽  
Author(s):  
André da Silva Salvaterra ◽  
Rosangela Felício dos Santos ◽  
Alexandre Barbosa Salaroli ◽  
Rubens Cesar Lopes Figueira ◽  
Michel Michaelovitch de Mahiques
Keyword(s):  
Atlantic Coast ◽  
Standard Penetration Test ◽  
Marine Isotope Stage ◽  
Brazilian Coast ◽  
South American ◽  
The South ◽  
Marine Deposits ◽  
South Eastern ◽  
Marine Isotope Stage 3 ◽  
New Evidence

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.

Influence of oceanic fronts on mesozooplankton abundance and grazing during spring in the south-western Atlantic

2016 ◽  
Vol 67 (5) ◽  
pp. 626 ◽  
Author(s):  
Rubens M. Lopes ◽  
Catarina R. Marcolin ◽  
Frederico P. Brandini
Keyword(s):  
Chlorophyll A ◽  
Daily Basis ◽  
Polar Front ◽  
Grazing Impact ◽  
Sampling Effort ◽  
Antarctic Polar Front ◽  
The South ◽  
Western Atlantic ◽  
Oceanic Fronts ◽  
Plankton Biomass

We investigated the influence of oceanic fronts on mesozooplankton distribution and grazing activity in the south-west Atlantic. Sampling was conducted during late spring 1993 along a north–south transect between subtropical waters off Brazil and Antarctic waters. Mesozooplankton abundance and biomass were ~10-fold higher in the Subtropical Confluence Zone (SCZ) and in the Antarctic Polar Front (APF) relative to subtropical and subantarctic waters beyond the influence of those frontal systems. Mesozooplankton was dominated by calanoid and cyclopoid copepods. Community ingestion rates ranged between 0.1 and 0.3mg chlorophyll-a m–2day–1 in interfrontal areas, increasing to 2.0 and 9.0mg chlorophyll-a m–2day–1 in the APF and SCZ respectively. Mesozooplankton grazing removed up to 40% of the total chlorophyll stock in the SCZ, and 22% in the APF, on a daily basis. These estimates suggest that mesozooplankton exert a significant grazing impact on phytoplankton over much of the frontal areas studied. Recent investigations have shown that the geographic position of oceanic fronts and plankton biomass maxima in the study area have remained basically the same from the time of our sampling effort to date, meaning that our results apply to present conditions.

Northward Migration of Antarctic Polar Front during the Quaternary: Planktic Foraminiferal Record from Southeast Indian Ocean

2021 ◽  
Vol 7 (1) ◽  
pp. 13-24
Author(s):  
Ashutosh Kumar Singh ◽  
Devesh K. Sinha
Keyword(s):  
Indian Ocean ◽  
Volume Expansion ◽  
Census Data ◽  
Cold Water ◽  
Species Group ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
The South ◽  
Ice Volume ◽  
The Antarctic

The ODP Hole 763A is influenced by the northward-flowing cold West Australian Current (WAC) and Southward flowing warm Leeuwin Current (LC). LC is a branch of the South Equatorial Current (SEC), which brings relatively warmer waters from the tropical Pacific Ocean into the Indian Ocean via Indonesian Throughflow (ITF). The modern planktic foraminiferal fauna thrives along the western margin of Australia. It consists mainly of warm water assemblages brought by the LC. The present study provides planktic foraminiferal census data from ODP Hole 763A, influenced by the LC and WAC, to document the history of cold water influence at the site during the quaternary. The northward migration of the Antarctic Polar Front (APF) and resultant intensification of the cold West Australian Current have been inferred based on the dramatic increase in the relative abundance of temperate water species group Globoconella at Hole 763A situated in the low latitude region. The Quaternary planktic foraminiferal census data shows several episodes of invasion of Globoconella. These intervals of high abundance of Globoconella group have been attributed to the intensification of WAC, probably due to Antarctic ice volume expansion and resultant northward migration of the APF at 0.05 Ma, 0.2 Ma, 0.45 Ma, 0.7 Ma and 1.2 Ma. We have documented that the amplitude of fluctuations in cold/warm events has increased after the Mid-Pleistocene Transition (MPT). LC is a heat supplier to the higher latitudes, its weakening during such intervals might have contributed to the ice volume expansion over Antarctica. Thus, the study proposes that the Antarctic ice cap formation creates a positive feedback mechanism by lowering sea level, reduced strength of LC due to a decrease in ITF and less heat supply towards the South Pole. All these phenomena add to further cooling.

scholarly journals Application of sediment core modelling to interpreting the glacial-interglacial record of Southern Ocean silica cycling

2007 ◽  
Vol 3 (3) ◽  
pp. 387-396 ◽  
Author(s):  
A. Ridgwell
Keyword(s):  
Southern Ocean ◽  
Sediment Core ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
Sea Ice Extent ◽  
Atlantic Sector ◽  
Silica Cycling ◽  
The North ◽  
Late Neogene ◽  
Primary Driver

Abstract. Sediments from the Southern Ocean reveal a meridional divide in biogeochemical cycling response to the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean, biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties provides an important model validation target for testing hypotheses of glacial-interglacial change against, particularly for understanding the causes of the concurrent variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand climates of the past by means of the mechanistic simulation of marine sediment core records. I find that a close match between model-predicted and observed down-core changes in sedimentary opal content can be achieved when changes in seasonal sea-ice extent are imposed, whereas the predicted sedimentary response to iron fertilization on its own is not consistent with sedimentary observations. The results of this sediment record model-data comparison supports previous inferences that the changing cryosphere is the primary driver of the striking features exhibited by the paleoceanographic record of this region.

scholarly journals The anatomy of the Antarctic polar front in the Drake Passage

1978 ◽  
Vol 83 (C12) ◽  
pp. 6093 ◽  
Author(s):  
Terrence M. Joyce ◽  
Walter Zenk ◽  
John M. Toole
Keyword(s):  
Drake Passage ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
The Antarctic

The diets and dietary segregation of sooty albatrosses (Phoebetria spp.) at subantarctic Marion Island

1995 ◽  
Vol 7 (1) ◽  
pp. 15-23 ◽  
Author(s):  
John Cooper ◽  
Norbert T.W. Klages
Keyword(s):  
Foraging Behaviour ◽  
Stomach Contents ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
Marion Island ◽  
The South ◽  
The Antarctic

Subantarctic Marion Island is one of the few localities where the congeneric albatrosses Phoebetria fusca and P. palpebrata breed sympatrically. Chicks of both species at Marion Island were induced to regurgitate their stomach contents after being fed. Liquid formed over half the diet by mass. Cephalopods occurred most frequently in both species' diets. In terms of mass, cephalopods formed the larger part of the diet of sooty albatrosses, whereas fish was more important to light-mantled sooty albatrosses. Crustaceans and birds were also recorded for both species. Squid of the families Onychoteuthidae, Histioteuthidae, Chiroteuthidae and Cranchiidae occurred most abundantly in both species. Most squid taken by both albatrosses were of species known to float after death, suggesting that scavenging plays an important role in the species' foraging behaviour. Light-mantled sooty albatrosses consumed more squid restricted to the south of the Antarctic Polar Front than did sooty albatrosses, supporting a trend to latitudinal segregation of the two species while foraging.

Particle export and the biological pump in the Southern Ocean

2004 ◽  
Vol 16 (4) ◽  
pp. 501-516 ◽  
Author(s):  
SUSUMU HONJO
Keyword(s):  
Organic Carbon ◽  
Southern Ocean ◽  
Carbon Particle ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
Biological Pump ◽  
The South ◽  
Regeneration Rate ◽  
Particle Export ◽  
The Antarctic

The organic carbon particle export to the interior layers in the Southern Ocean in the New Zealand–Tasmania Sector was approximately 170 mmolC m−2 yr−1. The export of particulate inorganic carbon in CaCO3 was 110 mmolC m−2 yr−1 and was contributed mostly by pteropods shells in the Antarctic Zones. The Si flux from biogenic opal at the sub-Antarctic Zone was 67 mmolSi m−2 yr−1 and rapidly increased to the south up to nearly 1 molSi m−2 yr−1 in the Antarctic Zone. The Antarctic Polar Front clearly demarcated the area where the biological pump was driven by CaCO3 to the north and biogenic SiO2 particle export to the south. Summer stratification caused by the sub-zero winter water layer in the Seasonal Ice Zone (SIZ) curtails the zooplankton community and hinders the replenishment of Fe. This hypothesis explains the large organic carbon export with large f- and export ratios at the SIZ and extremely large opal production at the Antarctic Circumpolar Zone. Estimated regeneration rate of CO2 from the export production and settling particulate fluxes of organic carbon in the water column between 100 m to 1 km was about 13 mmolC m−2 d−1 in the Antarctic Zone and Polar Frontal Zone.

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