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

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.

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 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.

scholarly journals Victoria Land, Antarctica: An Improved Geodynamic Interpretation Based on the Strain Rate Field of the Current Crustal Motion and Moho Depth Model

2020 ◽  
Vol 13 (1) ◽  
pp. 87
Author(s):  
Antonio Zanutta ◽  
Monia Negusini ◽  
Luca Vittuari ◽  
Leonardo Martelli ◽  
Paola Cianfarra ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ross Sea ◽  
East Antarctica ◽  
Gravity Potential ◽  
Moho Depth ◽  
Airborne Gravity ◽  
Narrow Strip ◽  
Continental Scale ◽  
Victoria Land ◽  
Marine Gravity

In Antarctica, the severe climatic conditions and the thick ice sheet that covers the largest and most internal part of the continent make it particularly difficult to systematically carry out geophysical and geodetic observations on a continental scale. It prevents the comprehensive understanding of both the onshore and offshore geology as well as the relationship between the inner part of East Antarctica (EA) and the coastal sector of Victoria Land (VL). With the aim to reduce this gap, in this paper multiple geophysical dataset collected since the 1980s in Antarctica by Programma Nazionale di Ricerche in Antartide (PNRA) were integrated with geodetic observations. In particular, the analyzed data includes: (i) Geodetic time series from Trans Antarctic Mountains DEFormation (TAMDEF), and Victoria Land Network for DEFormation control (VLNDEF) GNSS stations installed in Victoria Land; (ii) the integration of on-shore (ground points data and airborne) gravity measurements in Victoria Land and marine gravity surveys performed in the Ross Sea and the narrow strip of Southern Ocean facing the coasts of northern Victoria Land. Gravity data modelling has improved the knowledge of the Moho depth of VL and surrounding the offshore areas. By the integration of geodetic and gravitational (or gravity) potential results it was possible to better constrain/identify four geodynamic blocks characterized by homogeneous geophysical signature: the Southern Ocean to the N, the Ross Sea to the E, the Wilkes Basin to the W, and VL in between. The last block is characterized by a small but significant clockwise rotation relative to East Antarctica. The presence of a N-S to NNW-SSE 1-km step in the Moho in correspondence of the Rennick Geodynamic Belt confirms the existence of this crustal scale discontinuity, possibly representing the tectonic boundary between East Antarctica and the northern part of VL block, as previously proposed by some geological studies.

Sign in / Sign up

Export Citation Format

Share Document