Subduction invasion polarity switch from the Pacific to the Atlantic Ocean: A new geodynamic model of subduction initiation based on the Scotia Sea region

Subduction zones and their associated slabs are the main drivers of plate tectonics and mantle flow, but how these zones initiate remains enigmatic. In the Scotia Sea region, subduction started in the Late Cretaceous/Early Cenozoic in a pristine ocean basin setting devoid of other subduction/collisi...

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Bibliographic Details
Published in:Earth-Science Reviews
Main Authors: Schellart, W.P., Strak, V., Beniest, A., Duarte, J.C., Rosas, F.M.
Format: Article in Journal/Newspaper
Language:English
Published: 2023
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Online Access:https://research.vu.nl/en/publications/49c837c0-032d-4952-a8a2-f408a78225c7
https://doi.org/10.1016/j.earscirev.2022.104277
https://hdl.handle.net/1871.1/49c837c0-032d-4952-a8a2-f408a78225c7
http://www.scopus.com/inward/record.url?scp=85144802348&partnerID=8YFLogxK
http://www.scopus.com/inward/citedby.url?scp=85144802348&partnerID=8YFLogxK
https://www.sciencedirect.com/science/article/pii/S0012825222003610
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Summary:Subduction zones and their associated slabs are the main drivers of plate tectonics and mantle flow, but how these zones initiate remains enigmatic. In the Scotia Sea region, subduction started in the Late Cretaceous/Early Cenozoic in a pristine ocean basin setting devoid of other subduction/collision zones. How this subduction zone initiated remains intensely debated, as exemplified by the variability of published plate tectonic reconstructions. Despite such variability, several works argue for a subduction initiation mechanism, in which a South America-Antarctica relative plate motion change, in combination with a particular plate boundary geometry in the western Weddell Sea, caused convergence across a transform plate boundary segment that subsequently evolved into a subduction zone. Here we discuss this kinematic model of subduction initiation, and, following geometric and kinematic arguments, highlight several unsolved issues that call for alternative explanations. Furthermore, we present new tectonic reconstructions of the Scotia region involving a simpler middle-Late Cretaceous plate boundary configuration, which avoid the geometric and kinematic problems of earlier reconstructions and that call for a new mechanism of subduction initiation. We refer to this mechanism as Subduction Invasion Polarity Switch (SIPS), which involves a long-lived and wide subduction zone (South American-Antarctic subduction zone) with lower mantle slab penetration, which imposes major horizontal trench-normal compressive deviatoric stresses on the overriding plate. This plate consists of a narrow continental lithospheric (land) bridge at the trench (Cretaceous-Early Cenozoic Antarctica-South America land bridge) with oceanic lithosphere behind it (Weddell Sea-Atlantic Ocean). The stresses cause shortening and thrusting at the continent-ocean boundary in the backarc region of the overriding plate, forcing oceanic lithosphere under continental lithosphere, starting the subduction initiation process, and eventually leading to a ...