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The northern Patagonia Somuncura plateau basalts: a product of slab-induced, shallow asthenospheric upwelling?

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De Ignacio, Cristina and Lópe, Iván and Oyarzun Muñoz, Roberto and Márquez González, Álvaro (2001) The northern Patagonia Somuncura plateau basalts: a product of slab-induced, shallow asthenospheric upwelling? Terra Nova, 13 (2). pp. 117-121. ISSN ISSN: 0954-4879, ESSN: 1365-3121

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Official URL: http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3121.2001.00326.x/full





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The Meseta de Somuncura forms the largest basaltic plateau (20 000 km2 ) of southern Argentina (extra-Andean domain). Most of these tholeiitic to alkaline rocks were extruded at ~ 25 Ma (late Oligocene). The absence of rifting±thinning processes, plume activity, or slab-window phenomena leaves only one major possibility for the generation of Somuncura: asthenospheric ('OIB-like') corner flow leading to a transient thermal anomaly above the subducting plate. It is suggested herein that the intake of hot asthenosphere was forced into a favourable topography (concave-up) of the subducting plate, hen a major plate reorganization event (Farallon to Nazca) was taking place in late Oligocene to early Miocene time. The fast and vigorous intake of asthenosphere would have been induced by slab roll-back, leading to decoupling of the subducting plate. The Somuncura volcanic episode can be regarded as a marker of the passage from the extremely oblique subduction of Farallon, to the birth of the Nazca plate and roughly perpendicular convergence between South America and Nazca.

Item Type:Article
Uncontrolled Keywords:Meseta de Somuncura (Argentina), Basaltic
Subjects:Sciences > Geology > Petrology
ID Code:46162
Deposited On:29 Jan 2018 08:27
Last Modified:30 Jan 2018 08:38

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