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| Titel |
Formation of the Patagonian Plateau lavas: Insights from dynamical models |
| VerfasserIn |
Shu-Chuan Lin, Sun-Lin Chung |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073512
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| Zusammenfassung |
| The Patagonian basalt field that erupted between ~35Ë S and 52Ë S in South America is one
of the largest continental basaltic provinces. The genesis of the northern Patagonian intraplate
basalts has been linked to the shallow asthenospheric upwelling due to rollback
subduction and variations in slab curvature. In the southern Patagonia, the Chile Ridge
(Nazca-Antarctic spreading center) has been subducting at a low angle to the Chile Trench
at ~ 46Ë 20′ S since the Middle Miocene, forming the Patagonian slab window.
It has been suggested that the widespread alkaline back-arc basalts, the seismic
anisotropy patterns observed in the Chile Ridge subduction region and the rapid
changes in geochemical characteristics of the arc volcanics above the southern
edge of the subducting Nazca plate are controlled by mantle circulations associated
with the slab window. Recent observations and progress in dynamic models for
subduction zones provide new constraints in detailing the mantle flow field in the
vicinity of a slab window. However, the combined effects of a dynamic slab, mantle
rheology, plate age and variations in slab geometry have not been explored. In addition,
without either significant back-arc extension or the presence of mantle plume, the heat
source for generation of the voluminous lavas in the northern Patagonia is unclear.
Furthermore, the origin of the unusual trace element characteristics of lavas recovered from
the Chile Ridge adjacent to the Chile Trench, showing affinities to arc magmas,
remains enigmatic. To address these issues, three-dimensional numerical models with
a composite (Newtonian and non-Newtonian) rheology for the southern Andean
subduction system for region ~ 25Ë -55Ë S and 60Ë -100Ë W extending from the
surface to 1000 km depth are constructed. Model results and predictions for the
recent Patagonian magmatism and patterns of seismic anisotropy are presented. |
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