scholarly journals Tectonic Reconstructions of the Southernmost Andes and the Scotia Sea During the Opening of the Drake Passage

2016 ◽  
pp. 75-108 ◽  
Author(s):  
Graeme Eagles
Keyword(s):  
Drake Passage ◽  
Scotia Sea ◽  
Tectonic Reconstructions

scholarly journals Western Scotia Sea margins: Improved constraints on the opening of the Drake Passage

2006 ◽  
Vol 111 (B6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Emanuele Lodolo ◽  
Federica Donda ◽  
Alejandro Tassone
Keyword(s):  
Drake Passage ◽  
Scotia Sea

Structure and Variability of Mesoscale Perturbations of Ocean Currents in the Drake Passage and Scotia Sea

Oceanology ◽  
2019 ◽  
Vol 59 (2) ◽  
pp. 171-181 ◽  
Author(s):  
M. N. Koshlyakov ◽  
I. A. Repina ◽  
D. S. Savchenko ◽  
R. Y. Tarakanov ◽  
V. K. Taroyan
Keyword(s):  
Drake Passage ◽  
Ocean Currents ◽  
Scotia Sea

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.

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>

scholarly journals From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

2013 ◽  
Vol 40 (4) ◽  
pp. 394-405 ◽  
Author(s):  
SIMEON L. HILL
Keyword(s):  
Antarctic Krill ◽  
Drake Passage ◽  
Simulation Models ◽  
Reference Points ◽  
Multiple Predators ◽  
Scotia Sea ◽  
Current State ◽  
Management Measures ◽  
Spatial Subdivision ◽  
Ecosystem State

SUMMARYThe goals of ecosystem based management (EBM) are strategically ambiguous, meaning that they require interpretation to identify objectives for ecosystem state. Ecosystem states that are useful for achieving such objectives are known as reference points. Soft reference points specify both a state and a probability of the ecosystem being in that state. They are used with simulation models to identify management measures for which the risk of the ecosystem entering an undesirable state is below a specified level. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for the EBM of Antarctic krill fisheries. CCAMLR used soft reference points for the krill stock in the Scotia Sea and southern Drake Passage to set a regional catch limit. However, this catch limit needs spatial subdivision to protect predators from localized depletion. Model-based evaluations of different options for subdividing the catch limit used illustrative reference points to assess the depletion risk to multiple predators. This study demonstrates that the apparent risk is sensitive to the choice of reference point and method for aggregating modelled predators. EBM practitioners and stakeholders need to be aware that these factors could therefore bias comparisons of management measures. Nonetheless, qualitative distinctions between different spatial subdivision options are relatively consistent except at high levels of aggregation and extreme reference points. This study also demonstrates a lack of generality in the relationship between current and future ecosystem state. Thus, the EBM goal of maintaining ecosystem resilience implies different reference points for the current state of different ecosystem components. Despite early progress in defining soft reference points for the krill stock, CCAMLR has not yet defined reference points for krill predators. Structured dialogue aimed at identifying collective objectives might be necessary to achieve further progress in CCAMLR and other EBM organizations.

scholarly journals Frontal Circulation and Submesoscale Variability during the Formation of a Southern Ocean Mesoscale Eddy

2017 ◽  
Vol 47 (7) ◽  
pp. 1737-1753 ◽  
Author(s):  
Katherine A. Adams ◽  
Philip Hosegood ◽  
John R. Taylor ◽  
Jean-Baptiste Sallée ◽  
Scott Bachman ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Mesoscale Eddy ◽  
Drake Passage ◽  
Mathematical Framework ◽  
Intermediate Water ◽  
Surface Mixed Layer ◽  
Mode Water ◽  
Scotia Sea ◽  
Simplifying Assumptions ◽  
Circumpolar Current

AbstractObservations made in the Scotia Sea during the May 2015 Surface Mixed Layer Evolution at Submesoscales (SMILES) research cruise captured submesoscale, O(1–10) km, variability along the periphery of a mesoscale O(10–100) km meander precisely as it separated from the Antarctic Circumpolar Current (ACC) and formed a cyclonic eddy ~120 km in diameter. The meander developed in the Scotia Sea, an eddy-rich region east of the Drake Passage where the Subantarctic and Polar Fronts converge and modifications of Subantarctic Mode Water (SAMW) occur. In situ measurements reveal a rich submesoscale structure of temperature and salinity and a loss of frontal integrity along the newly formed southern sector of the eddy. A mathematical framework is developed to estimate vertical velocity from collocated drifter and horizontal water velocity time series, under certain simplifying assumptions appropriate for the current dataset. Upwelling (downwelling) rates of O(100) m day−1 are found in the northern (southern) eddy sector. Favorable conditions for submesoscale instabilities are found in the mixed layer, particularly at the beginning of the survey in the vicinity of density fronts. Shallower mixed layer depths and increased stratification are observed later in the survey on the inner edge of the front. Evolution in temperature–salinity (T–S) space indicates modification of water mass properties in the upper 200 m over 2 days. Modifications along σθ = 27–27.2 kg m−3 have climate-related implications for mode and intermediate water transformation in the Scotia Sea on finer spatiotemporal scales than observed previously.

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