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

Riley, Teal R.; Carter, Andrew; Leat, P. T.; Burton‐Johnson, Alex; Bastías, Joaquín; Spikings, Richard; Tate, Alex; Bristow, Charlie S.

doi:10.1016/j.epsl.2019.04.031

Cited by 25 publications

(35 citation statements)

References 46 publications

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“…), which is difficult to reconcile with a position just east of South Africa [42,62] (and cites therein). Permian ages are common at these latitudes in the Darwin Cordillera, with a more prominent peak at c. 270 Ma [65]; this is well documented for the Patagonian Andes, with a large well-defined 260-300 Ma population likely derived from the Gondwanide belt formed during the Carboniferous-Permian assembly of Patagonia [66], bracketed by Suárez et al [67] between 255-268 Ma, and even closer, in the South Georgia Island, at its previous position adjacent to eastern Tierra del Fuego Island, with a dominant younger peak at 275 Ma [68,69].…”

Section: New Data On the Malvinas Plateaumentioning

confidence: 84%

The Malvinas (Falkland) Plateau Derived from Africa? Constraints for its Tectonic Evolution

Ramos

Chemale

Lovecchio³

et al. 2019

scirevfew

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The latest studies on the tectonic evolution of the Malvinas (Falkland) Islands and their adjacent continental plateau further east are analyzed to assess a long controversy regarding the origin of these islands. Although there has been a controversy for several decades on this subject, new technologies and exploratory drilling have brought new data, however the debate of the geological evolution of this area remains open. The two dominant hypotheses are analyzed by assessing the eventual collision between the islands and the South American continent, the presence of a large transcontinental fault such as Gastre, the potential 180º rotation of the Malvinas Islands, and the occurrence of a mega-decollement with opposite vergence. These hypotheses are contrasted with the processes that have occurred in Patagonia, especially those based on the new isotopic data on the Maurice Ewing Bank at the eastern end of the Malvinas Plateau, and the current knowledge of the adjacent Malvinas Basin. The new data highlights the inconsistencies of certain models that proposed these islands migrated from the eastern African coasts near Natal, to their current position and rotated 180º on a vertical axis. The new observations are consolidating the hypothesis that postulates that the islands have been part of the South American continent since before the Paleozoic.

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Section: New Data On the Malvinas Plateaumentioning

confidence: 84%

The Malvinas (Falkland) Plateau Derived from Africa? Constraints for its Tectonic Evolution

Ramos

Chemale

Lovecchio³

et al. 2019

scirevfew

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“…Подобные метки характеризуют как коровый материал, так и субдукционный. Аналогичные характеристики наблюдались раннее для базальтов Атлантического и Индийского океанов [2,6,10,12,15].…”

Section: состав толеитов хребта шакаunclassified

Petrochemical features of tholeiites from the Shaka ridge (South Atlantic)

Rumyantseva¹,

Vanshteyn²,

Скублов

2021

PMI

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The article presents original data of chemical composition of tholeiitic basaltoids and andesites, dredged from the Shaka Ridge (South Atlantic) in the course of field research in spring 2016 on the scientific expedition vessel “Akademik Fedorov”. The analytical part of the work on estimating the contents of petrogenic, trace and rare-earth elements was carried out using the classical method (“wet chemistry”), X-ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The studied samples demonstrate elevated concentrations of large-ion lithophile elements, or LILE, (Ba, Rb, Pb) and light rare earth elements, or LREE, (La, Ce, Nd, Sm) relative to high field strength elements, or HFSE, (Nb, Ta) and heavy rare earth elements, or HREE, (Dy, Yb, Lu). The specifics of trace element geochemistry suggest a significant contribution of crustal or subduction components to the magmas of the Shaka Ridge. Discrimination diagrams of basaltoids and allied rocks with fields of different geodynamic settings indicate that they were formed in the setting of the mid-ocean ridge basalt (MORB). The reason behind the appearance of subduction and crustal marks in the rocks is possibly associated with assimilation of crustal matter by magmas or lies in their inheritance from the mantle source.

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“…3 and 4). Based on field investigations of South Georgia, and geochemistry and geochronology of dredge samples of the North Scotia Ridge banks, they are interpreted as continental fragments that share a geological affinity with the Fuegian Andes (Carter et al, 2014;Dalziel et al, 1975;Mukasa and Dalziel, 1996;Pandey et al, 2010;Riley et al, 2019;Storey and Mair, 1982;Storey et al, 1977). The ridge is separated from the Falkland Plateau to the north by the Falkland Trough, a bathymetric depression that formed as part of the South American-Scotia transform plate boundary (Figs.…”

Section: Modern Geological Architecture Of the Scotia Sea Regionmentioning

confidence: 99%

Subduction initiation in the Scotia Sea region and opening of the Drake Passage: when and why?

Lagemaat

Vaes

Kosters

et al. 2021

Preprint

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<p>During evolution of the South Sandwich subduction zone, which has consumed South American plate oceanic lithosphere, somehow continental crust of both the South American and Antarctic plates have become incorporated into its upper plate. Continental fragments of both plates are currently separated by small oceanic basins in the upper plate above the South Sandwich subduction zone, in the Scotia Sea region, but how fragments of both continents became incorporated in the same upper plate remains enigmatic. Here we present an updated kinematic reconstruction of the Scotia Sea region using the latest published marine magnetic anomaly constraints, and place this in a South America-Africa-Antarctica plate circuit in which we take intracontinental deformation into account. We show that a change in fracture zone orientation in the Weddell Sea requires that previously inferred initiation of subduction of South American oceanic crust of the northern Weddell below the eastern margin of South Orkney Islands continental crust, then still attached to the Antarctic Peninsula, already occurred around 80 Ma. We propose that subsequently, between ~71-50 Ma, the trench propagated northwards into South America by delamination of South American lithosphere: this resulted in the transfer of delaminated South American continental crust to the overriding plate of the South Sandwich subduction zone. We show continental delamination may have been facilitated by absolute southward motion of South America that was resisted by South Sandwich slab dragging. Pre-drift extension preceding the oceanic Scotia Sea basins led around 50 Ma to opening of the Drake Passage, preconditioning the southern ocean for the Antarctic Circumpolar Current. This 50 Ma extension was concurrent with a strong change in absolute plate motion of the South American Plate that changed from S to WNW, leading to upper plate retreat relative to the more or less mantle stationary South Sandwich Trench that did not partake in the absolute plate motion change. While subduction continued, this mantle-stationary trench setting lasted until ~30 Ma, after which rollback started to contribute to back-arc extension. We find that roll-back and upper plate retreat have contributed more or less equally to the total amount of ~2000 km of extension accommodated in the Scotia Sea basins. We highlight that viewing tectonic motions in a context of absolute plate motion is key for identifying slab motion (e.g. rollback, trench-parallel slab dragging) and consequently mantle-forcing of geological processes.</p>

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

Cited by 25 publications

References 46 publications

The Malvinas (Falkland) Plateau Derived from Africa? Constraints for its Tectonic Evolution

The Malvinas (Falkland) Plateau Derived from Africa? Constraints for its Tectonic Evolution

Petrochemical features of tholeiites from the Shaka ridge (South Atlantic)

Subduction initiation in the Scotia Sea region and opening of the Drake Passage: when and why?

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