The somuncura large igneous province in Patagonia: Interaction of a transient mantle thermal anomaly with a subducting slab

• Autores: Kay, S.M.; Ardolino, A.A.; Gorring, M.L.; Ramos, V.A.
• Año de publicación: 2007
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: J. Pet. 2007;48(1):43-77
• Materia: Large igneous province (LIP); Patagonia; Plume-like upwelling; Slab interaction; Somuncura plateau; crustal contamination; large igneous province; magma chemistry; magmatism; mantle source; melting; trace element; Patagonia; South America
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

The Oligo-Miocene Somuncura province is the largest (∼55 000 km2) back-arc mafic volcanic field in Patagonia, and one of Earth's largest with no clear link to a hotspot or major extension. Major and trace element and Sr-Nd-Pb isotopic data suggest involvement of a plume-like component in the mantle magma source mixed with hydrous, but not high field strength element (HFSE)-depleted components, from a disintegrating subducting plate. Magmatism is attributed to mantle upwelling related to disturbances during plate reorganization, possibly at a time when the South America plate was nearly stationary over the underlying mantle. Melting was enhanced by hydration of the mantle during Paleogene subduction. Crustal contamination was minimal in a refractory crust that had been extensively melted in the Jurassic. Eruption began with low-volume intraplate alkaline mafic flows with depleted Nd-Sr isotopic signatures. These were followed by voluminous ∼29-25 Ma tholeiitic mafic flows with flat light and steep heavy rare earth element (REE) patterns, intraplate-like La/Ta ratios, arc-like Ba/La ratios and enriched Sr-Nd isotopic signatures. Their source can be explained by mixing EM1-Tristan da Cunha-like and depleted mantle components with subduction-related components. Post-plateau ∼24-17 Ma alkaline flows with steep REE patterns, high incompatible element abundances, and depleted Sr-Nd isotopic signatures mark the ebbing of the mantle upwelling. Copyright © 2007 Oxford University Press.
Fil:Ardolino, A.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.