The Cenozoic tectonic evolution of the Scotia Sea area

2020 ◽  
Author(s):  
Anne Oldenhage ◽  
Anouk Beniest ◽  
Wouter P. Schellart
Keyword(s):  
Tectonic Evolution ◽  
Drake Passage ◽  
Sea Level Changes ◽  
Scotia Sea ◽  
Scotia Ridge ◽  
The North ◽  
Reconstruction Software ◽  
Circumpolar Current ◽  
Global Sea Level ◽  
The Antarctic

<p>The breakup of the southern edge of Gondwanaland resulted in the formation of the Scotia Plate and the opening of Drake Passage throughout the Cenozoic. During the same period, the Tasman Seaway opened, although the timing of this opening is much better constrained. Rapid cooling of the Antarctic continent followed the openings of Drake Passage and the Tasman Seaway. The opening of Drake Passage or the Tasman seaway allowed the onset of the Antarctic Circumpolar Current, which is held responsible for the late Miocene global cooling, but discussions about the most important opening are still ongoing.</p><p>The opening of Drake Passage and the development of the Scotia plate have been studied in multitude, but paleogeographic reconstructions show many differences and inconsistencies in both timing of opening Drake Passage as well as paleo-locations of crustal segments. The paleogeographic or tectonic reconstructions of the opening of Drake Passage and the formation of the Scotia plate are hard to compare, because differences in shapes of crustal segments, geographic projections and relative movements of segments chosen by previous authors make it difficult to observe similarities and differences between the different reconstructions.</p><p>We present a thorough analysis of the previously published paleogeographic reconstructions with the aim to identify agreements and inconsistencies between these reconstructions. We re-defined the crustal segments that formed after the break-up of Gondwanaland by re-interpreting the bathymetry and magnetic anomalies of the study area. We re-modelled and compared georeferenced reconstructions from earlier studies in GPlates plate reconstruction software using our own defined crustal segments.</p><p>This comparison shows that the different reconstructions agree quite well along the South Scotia Ridge, but that the North Scotia Ridge shows significant variations between different reconstructions or is not even considered in the reconstructions. Also, the nature and age of the crust of the Central Scotia Sea is heavily discussed, resulting in different opening scenarios. We argue that the tectonic evolution of the North Scotia Ridge and Central Scotia Sea is a crucial factor in identifying the timing of the development of an ocean gateway. We made a new tectonic reconstruction of the North Scotia Ridge crustal segments with less overlaps and gaps between the reconstructed crustal segments.</p><p>The next step would be to compare the global sea-level changes and paleo-bathymetry with the different opening scenarios. Because we standardized all scenarios with the same crustal segments, we will then be able to provide opening ages of Drake Passage for the different scenarios that can be compared in a quantitative way.</p>

Medium-scale heat fluxes across the Antarctic Circumpolar Current in the Drake Passage and western Scotia Sea

1996 ◽  
Vol 8 (4) ◽  
pp. 369-378
Author(s):  
Alberto R. Piola ◽  
Monica B. Grasselli
Keyword(s):  
Antarctic Circumpolar Current ◽  
Heat Content ◽  
Drake Passage ◽  
Polar Front ◽  
Heat Fluxes ◽  
Scotia Sea ◽  
Medium Scale ◽  
Scale Temperature ◽  
Circumpolar Current ◽  
The Antarctic

Closely spaced continuous temperature profiles from expendable bathythermographs launched along two sections across the Drake Passage and western Scotia Sea in the summer 1981–1982 are used to examine the vertical medium-scale (∼10–100 m) temperature fine structure. The large-scale temperature structure across the frontal regimes characteristic of the Antarctic Circumpolar Current and the cross-frontal structure of the upper ocean are discussed. In the Drake Passage the heat content drops about 0.5 × 102 Kcal cm−2 (2 × 109 J m−2) across the Subantarctic Zone and 0.9 × 102 Kcal cm−2 (3.6 − 109 J m−2) across the Polar Front. In the Scotia Sea the heat content changes across the front are not as prominent. The statistical model of Joyce (1977) is used to quantify the heat fluxes across the fronts produced by the medium-scale temperature interleaving. In the Drake Passage the estimated heat flux is 0.32 × 10−3 °C m s−1 (1.3 × 103 W m−2) across the Subantarctic Front and 0.46 × 10−3 °C m s−1 (1.9 × 103 W m−2) across the Polar Front. In the Scotia Sea the estimated heat flux is larger in the Polar Front reaching 0.71 × 10−3 °C m s−1 (2.9 × 103 W m−2). The medium-scale fine structure heat fluxes are about 10% of the existing estimates of the mesoscale eddy heat fluxes and comparable to heat fluxes associated with the meridional flow of deep and bottom waters across the Antarctic Circumpolar Current.

scholarly journals The flow of the Antarctic Circumpolar Current over the North Scotia Ridge

2010 ◽  
Vol 57 (1) ◽  
pp. 14-28 ◽  
Author(s):  
Inga J. Smith ◽  
David P. Stevens ◽  
Karen J. Heywood ◽  
Michael P. Meredith
Keyword(s):  
Antarctic Circumpolar Current ◽  
Scotia Ridge ◽  
The North ◽  
Circumpolar Current ◽  
The Antarctic

scholarly journals Intrinsic variability of the Antarctic Circumpolar Current system: low- and high-frequency fluctuations of the Argentine Basin flow

Ocean Science ◽  
2014 ◽  
Vol 10 (2) ◽  
pp. 201-213 ◽  
Author(s):  
G. Sgubin ◽  
S. Pierini ◽  
H. A. Dijkstra
Keyword(s):  
High Frequency ◽  
Antarctic Circumpolar Current ◽  
Current System ◽  
Low Frequency ◽  
Drake Passage ◽  
Ocean Model ◽  
Intrinsic Variability ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Argentine Basin

Abstract. In this paper, the variability of the Antarctic Circumpolar Current system produced by purely intrinsic nonlinear oceanic mechanisms is studied through a sigma-coordinate ocean model, implemented in a large portion of the Southern Ocean at an eddy-permitting resolution under steady surface heat and momentum fluxes. The mean transport through the Drake Passage and the structure of the main Antarctic Circumpolar Current fronts are well reproduced by the model. Intrinsic variability is found to be particularly intense in the Subantarctic Front and in the Argentine Basin, on which further analysis is focused. The low-frequency variability at interannual timescales is related to bimodal behavior of the Zapiola Anticyclone, with transitions between a strong and collapsed anticyclonic circulation in substantial agreement with altimeter observations. Variability on smaller timescales shows clear evidence of topographic Rossby-wave propagation along the eastern and southern flanks of the Zapiola Rise and of mesoscale eddies, also in agreement with altimeter observations. The analysis of the relationship between the low- and high-frequency variability suggests possible mechanisms of mutual interaction.

scholarly journals The Osservatorio Geofisico Sperimentale marine magnetic surveys in the Antarctic Seas

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
E. Lodolo ◽  
F. Coren ◽  
C. Zanolla
Keyword(s):  
Tectonic Evolution ◽  
Ross Sea ◽  
Austral Summer ◽  
Geological Structure ◽  
Seismic Profiles ◽  
Scotia Sea ◽  
Geophysical Surveys ◽  
Scientific Results ◽  
The Antarctic ◽  
Derived Data

About 40 000 km of marine magnetic and gradiometric data have been collected during eight geophysical surveys conducted since the Austral summer 1987/1988 in the circum-antarctic seas, by the research vessel OGS-Explora. For the most surveyed areas (Ross Sea, Southwestern Pacific Ocean, and Southern Scotia Sea), the analysis of the acquired data have contributed to clarify important aspects of their geological structure and tectonic evolution. The main scientific results, obtained combining other available geophysical data (multichannel seismic profiles and satellite-derived data), will be briefly illustrated.

scholarly journals Geochronology and geochemistry of the northern Scotia Sea: A revised interpretation of the North and West Scotia ridge junction

2019 ◽  
Vol 518 ◽  
pp. 136-147 ◽  
Author(s):  
Teal R. Riley ◽  
Andrew Carter ◽  
Philip T. Leat ◽  
Alex Burton-Johnson ◽  
Joaquin Bastias ◽  
...  
Keyword(s):  
Scotia Sea ◽  
Scotia Ridge ◽  
The North

scholarly journals The Skytrain plate and tectonic evolution of southwest Gondwana since Jurassic times

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Graeme Eagles ◽  
Hannes Eisermann
Keyword(s):  
Tectonic Evolution ◽  
Drake Passage ◽  
Weddell Sea ◽  
Falkland Islands ◽  
South American ◽  
Long Distance ◽  
Oblique Collision ◽  
Scotia Sea ◽  
Continental Extension ◽  
Pacific Margin

AbstractUncertainty about the structure of the Falkland Plateau Basin has long hindered understanding of tectonic evolution in southwest Gondwana. New aeromagnetic data from the basin reveal Jurassic-onset seafloor spreading by motion of a single newly-recognized plate, Skytrain, which also governed continental extension in the Weddell Sea Embayment and possibly further afield in Antarctica. The Skytrain plate resolves a nearly century-old controversy by requiring a South American setting for the Falkland Islands in Gondwana. The Skytrain plate’s later motion provides a unifying context for post-Cambrian wide-angle paleomagnetic rotation, Cretaceous uplift, and post-Permian oblique collision in the Ellsworth Mountains of Antarctica. Further north, the Skytrain plate’s margins built a continuous conjugate ocean to the Weddell Sea in the Falkland Plateau Basin and central Scotia Sea. This ocean rules out venerable correlation-based interpretations for a Pacific margin location and subsequent long-distance translation of the South Georgia microcontinent as the Drake Passage gateway opened.

scholarly journals Coupling Influences of ENSO and PDO on the Inter-Decadal SST Variability of the ACC around the Western South Atlantic

2019 ◽  
Vol 11 (18) ◽  
pp. 4853
Author(s):  
You-Lin Wang ◽  
Yu-Chen Hsu ◽  
Chung-Pan Lee ◽  
Chau-Ron Wu
Keyword(s):  
Antarctic Circumpolar Current ◽  
Water Mass ◽  
Southern Oscillation ◽  
Drake Passage ◽  
South Atlantic ◽  
Sst Variability ◽  
The Pacific ◽  
Circumpolar Current ◽  
The Antarctic

The Antarctic Circumpolar Current (ACC) plays an important role in the climate as it balances heat energy and water mass between the Pacific and Atlantic Oceans through the Drake Passage. However, because the historical measurements and observations are extremely limited, the decadal and long-term variations of the ACC around the western South Atlantic Ocean are rarely studied. By analyzing reconstructed sea surface temperatures (SSTs) in a 147-year period (1870–2016), previous studies have shown that SST anomalies (SSTAs) around the Antarctic Peninsula and South America had the same phase change as the El Niño Southern Oscillation (ENSO). This study further showed that changes in SSTAs in the regions mentioned above were enlarged when the Pacific Decadal Oscillation (PDO) and the ENSO were in the same warm or cold phase, implying that changes in the SST of higher latitude oceans could be enhanced when the influence of the ENSO is considered along with the PDO.

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