scholarly journals Tectonics of the Southern Ocean passive margins in the Africa – East Antarctica region

2019 ◽  
pp. 25-42
Author(s):  
E. N. Melankholina ◽  
N. M. Sushchevskaya
Keyword(s):  
Southern Ocean ◽  
Upper Jurassic ◽  
East Antarctica ◽  
Significant Feature ◽  
Proximal Margin ◽  
Passive Margins ◽  
Initial Stage ◽  
Gondwana Supercontinent ◽  
African Superplume ◽  
Conjugate Margins

Based on geological and geophysical data for the conjugate margins of Africa – East Antarctica, the peculiarities of preparation of the breakup central Gondwana supercontinent are discussed. When using the historical approach, a significant inheritance of the Middle-Upper Jurassic tectono-magmatic development from the preceding time is shown. The first location of tectono-magmatic activity in zones of weakness on the proximal margin, its subsequent migration to distal margins and further oceanic opening is established. The geochemical features of magmas of the region and their sources are under discussion. Evidence for the decisive influence of the Karoo-Mod plume on the development of magmatism is presented. A significant feature of the plume manifestation is considered: the presence of high-magnesian ferruginous picrites , formed by melting of a pyroxenite source with specific composition, coinciding with the central part of the plume and corresponding to the earliest eruptions. We determined the source of magmatism at the initial stage could have been the substance of a rising plume, and magmas reached the surface through existing fractures without interacting with the lithosphere. In the course of evolution, the admixture of pyroxenites in the source decreased and the melts acquired the features of the melting lithospheric mantle, which was reflected in the isotopic characteristics of the melts with a predominance of the enriched EM II component. The structure and magmatism of the Southern Ocean and South Atlantic are compared. Also discussed the locations of the Mesozoic Karoo-Maud and Tristan plumes, as well as the zones of the subsequent breakup of Gondwana, above the margin of the African superplume, indicating a relationship between surface and deep-seated events, is discussed.

Tectonics of the Southern Ocean Passive Margins in the Africa–East Antarctica Region

Geotectonics ◽  
2019 ◽  
Vol 53 (4) ◽  
pp. 468-484
Author(s):  
E. N. Melankholina ◽  
N. M. Sushchevskaya
Keyword(s):  
Southern Ocean ◽  
East Antarctica ◽  
Passive Margins

Stratigraphy of Antarctic late Cenozoic pectinid-bearing deposits

1998 ◽  
Vol 10 (2) ◽  
pp. 161-170 ◽  
Author(s):  
H.A. Jonkers
Keyword(s):  
Southern Ocean ◽  
Food Availability ◽  
Habitat Loss ◽  
Antarctic Peninsula ◽  
East Antarctica ◽  
Combined Effects ◽  
Late Cenozoic ◽  
Late Pliocene ◽  
Antarctic Waters ◽  
The Antarctic

Antarctic late Cenozoic pectinid-bearing sedimentary strata are chiefly confined to localities in the northern part of the Antarctic Peninsula, in the McMurdo Sound area, and Marine Plain, East Antarctica. Ages of these deposits range from Oligocene to Holocene. Chlamys-like scallops, which are absent from today's Southern Ocean, thrived in Antarctic waters during both glacial and interglacial episodes, but disappeared during the Late Pliocene. Their extinction is believed to result from the combined effects of increased carbonate solubility, habitat loss and limitations in food availability, associated with major cooling.

Distribution of major and minor elements in the surface water of Southern Ocean near east Antarctica

2016 ◽  
Vol 58 (2) ◽  
pp. 06-11
Author(s):  
Pawan Kumar Bharti ◽  
◽  
Bhupesh Sharma ◽  
Narendra Pal ◽  
R. K. Singh ◽  
...  
Keyword(s):  
Surface Water ◽  
Southern Ocean ◽  
Near East ◽  
East Antarctica ◽  
Minor Elements

scholarly journals MONITORING OF THE NELLA FJORD WATER-ICE ECOSYSTEM (PRUDS BAY, EAST ANTARCTIC): SEASON RAE-65

2020 ◽  
Vol 48 (2) ◽  
pp. 163-165
Author(s):  
I. A. Melnikov
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
East Antarctica ◽  
Water Ice ◽  
Project Assessment ◽  
Antarctic Sea Ice ◽  
Antarctic Expedition ◽  
Russian Antarctic Expedition ◽  
The Antarctic

During the seasonal work of the Russian Antarctic expedition (RAE-65), the monitoring of the water-ice ecological system was conducted in the Nella fjord (Prude Bay, East Antarctica). This monitoring is conducted annually since the IPY in 2007 in frames of the project “Assessment of the ecology of the Antarctic sea ice zone” (“Krial”) (Melnikov, 2020). The purpose of the monitoring is the assessment of the role of water-ice biota in global biosphere processes in the Southern Ocean.

scholarly journals Iron in ice cores from Law Dome, East Antarctica: implications for past deposition of aerosol iron

1998 ◽  
Vol 27 ◽  
pp. 365-370 ◽  
Author(s):  
R. Edwards ◽  
P. N. Sedwick ◽  
Vin Morgan ◽  
C. F. Boutron ◽  
S. Hong
Keyword(s):  
Southern Ocean ◽  
Late Holocene ◽  
Ice Core ◽  
Iron Concentration ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Iron Deposition ◽  
Past Century ◽  
Preliminary Estimate

Total-dissolvable iron has been measured in sections of three ice cores from Law Dome, East Antarctica, and the results used to calculate atmospheric iron deposition over this region during the late Holocene and to provide a preliminary estimate of aerosol iron deposition during the Last Glaciol Maximum I LGM). Ice-core sections dating from 56-2730 BP (late Holocene) and ~18000 BP (LGM) were decontaminated using trace-metal clean techniques, and total-dissolvable iron was determined in the acidified meltwatcrs by flow-injection analysis. Our results suggest that the atmospheric iron flux onto the Law Dome region has varied significantly over time-scales ranging from seasonal to Glaciol-interglaciol. The iron concentrations in ice-core sections from the past century suggest (1) a 2 4-fold variation in the atmospheric iron flux over a single annual cycle, with the highest flux occurring during the spring and summer, and (2) a nearly 7-fold variation in the annual maximum atmospheric iron flux over a 14 year period. The average estimated atmospheric iron flux calculated from our late-Holocene samples is 0.056-0.14 mg m a−1, which agrees well with Holocene flux estimates derived from aluminium measurements in inland Antarctic ice cores and a recent order-of-magnitude estimate of present-day atmospheric iron deposition over the Southern Ocean. The iron concentration of an ice-corc section dating from the LGM was more than 50 times higher than in the late-Holocene ice samples. Using a snow-accumulation rate estimate of 130 kg m −2 a−1 for this period, we calculate 0.87 mgm −2 a−1 as a preliminary estimate of atmospheric iron deposition during the LGM, which is 6-16 times greater than our average late-Holocene iron flux. Our data are consistent with the suggestion that there was a significantly greater flux of atmospheric iron onto the Southern Ocean during the LGM than during then Holocene.

scholarly journals Warm Middle Jurassic–Early Cretaceous high-latitude sea-surface temperatures from the Southern Ocean

2012 ◽  
Vol 8 (1) ◽  
pp. 215-226 ◽  
Author(s):  
H. C. Jenkyns ◽  
L. Schouten-Huibers ◽  
S. Schouten ◽  
J. S. Sinninghe Damsté
Keyword(s):  
Southern Ocean ◽  
Early Cretaceous ◽  
Middle Jurassic ◽  
Warming Trend ◽  
Upper Jurassic ◽  
Climatic Conditions ◽  
Sea Surface ◽  
Polar Regions ◽  
Sea Surface Temperatures ◽  
Surface Temperatures

Abstract. Although a division of the Phanerozoic climatic modes of the Earth into "greenhouse" and "icehouse" phases is widely accepted, whether or not polar ice developed during the relatively warm Jurassic and Cretaceous Periods is still under debate. In particular, there is a range of isotopic and biotic evidence that favours the concept of discrete "cold snaps", marked particularly by migration of certain biota towards lower latitudes. Extension of the use of the palaeotemperature proxy TEX86 back to the Middle Jurassic indicates that relatively warm sea-surface conditions (26–30 °C) existed from this interval (∼160 Ma) to the Early Cretaceous (∼115 Ma) in the Southern Ocean, with a general warming trend through the Late Jurassic followed by a general cooling trend through the Early Cretaceous. The lowest sea-surface temperatures are recorded from around the Callovian–Oxfordian boundary, an interval identified in Europe as relatively cool, but do not fall below 25 °C. The early Aptian Oceanic Anoxic Event, identified on the basis of published biostratigraphy, total organic carbon and carbon-isotope stratigraphy, records an interval with the lowest, albeit fluctuating Early Cretaceous palaeotemperatures (∼26 °C), recalling similar phenomena recorded from Europe and the tropical Pacific Ocean. Extant belemnite δ18O data, assuming an isotopic composition of waters inhabited by these fossils of −1‰ SMOW, give palaeotemperatures throughout the Upper Jurassic–Lower Cretaceous interval that are consistently lower by ∼14 °C than does TEX86 and the molluscs likely record conditions below the thermocline. The long-term, warm climatic conditions indicated by the TEX86 data would only be compatible with the existence of continental ice if appreciable areas of high altitude existed on Antarctica, and/or in other polar regions, during the Mesozoic Era.

scholarly journals The Climatology and Trend of Surface Wind Speed over Antarctica and the Southern Ocean and the Implication to Wind Energy Application

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 108 ◽  
Author(s):  
Lejiang Yu ◽  
Shiyuan Zhong ◽  
Bo Sun
Keyword(s):  
Southern Ocean ◽  
Wind Energy ◽  
Antarctic Peninsula ◽  
Surface Wind ◽  
East Antarctica ◽  
Positive Trend ◽  
Self Organizing Map ◽  
Coastal Regions ◽  
Ice Shelves ◽  
The Antarctic

Surface wind trends and variability over Antarctica and the Southern Ocean and their implications to wind energy in the region are analyzed using the gridded ERA-Interim reanalysis data between 1979 and 2017 and the Self-Organizing Map (SOM) technique. In general, surface winds are stronger over the coastal regions of East Antarctica and the Transantarctic Mountains and weaker over the Ross and Ronne ice shelves and the Antarctic Peninsula; and stronger in winter and weaker in summer. Winds in the southern Indian and Pacific Oceans and along coastal regions exhibit a strong interannual variability that appears to be correlated to the Antarctic Oscillation (AAO) index. A significantly positive trend in surface wind speeds is found across most regions and about 20% and 17% of the austral autumn and summer wind trends, respectively, and less than 1% of the winter and spring wind trends may be explained by the trends in the AAO index. Except for the Antarctic Peninsula, Ronne and Ross ice shelves, and small areas in the interior East Antarctica, most of the continent is found to be suitable for the development of wind power.

Australodelphis mirus, a bizarre new toothless ziphiid-like fossil dolphin (Cetacea: Delphinidae) from the Pliocene of Vestfold Hills, East Antarctica

2002 ◽  
Vol 14 (1) ◽  
pp. 37-54 ◽  
Author(s):  
R. Ewan Fordyce ◽  
Patrick G. Quilty ◽  
James Daniels
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
East Antarctica ◽  
Antarctic Waters ◽  
Close Relationship ◽  
Near Shore ◽  
Beaked Whales ◽  
Upper Jaw ◽  
Vestfold Hills ◽  
Suture Patterns

Australodelphis mirus (Delphinidae n. gen., n. sp) is a small extinct Early Pliocene dolphin known from five individuals from shallow-water strata of the Sørsdal Formation, Vestfold Hills, East Antarctica. Australodelphis mirus is the first higher vertebrate named from the Oligocene-Pleistocene interval on land in Antarctica, and is the first cetacean fossil from the polar margin of circum-Antarctic Southern Ocean that postdates the break-up of Gondwana. The dolphin is convergent in skull form with some living beaked whales (Mesoplodon spp.; Family Ziphiidae) in its long, narrow and toothless upper jaw and face, but skull suture patterns, basicranial sinuses, and ear-bones indicate close relationship with living long-beaked dolphins (Delphinidae). Australodelphis mirus perhaps was a suction-feeding squid-eater which occupied quiet near-shore shelf waters influenced by glaciers but probably lacking major sea-ice. Possible ecological equivalents of A. mirus (small ziphiids, long-beaked dolphins) do not occupy Antarctic waters today, perhaps excluded by cold conditions and/or sea-ice cover. Earlier Pliocene cetaceans worldwide reveal significant extinct and sometimes bizarre taxa, and extant families with ranges quite different from today, pointing to climate-related changes in cetacean ecology in the last 2–3 million years.

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