The somuncura large igneous province in Patagonia

Interaction of a transient mantle thermal anomaly with a subducting slab

S. Mahlburg Kay, A. A. Ardolino, Matthew Gorring, V. A. Ramos

Research output: Contribution to journalArticleResearchpeer-review

55 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)43-77
Number of pages35
JournalJournal of Petrology
Volume48
Issue number1
DOIs
StatePublished - 1 Jan 2007

Fingerprint

large igneous province
Rare earth elements
temperature anomaly
slab
Earth mantle
slabs
anomalies
mantle
Trace Elements
Hydration
Refractory materials
Melting
rare earth element
Contamination
subduction
Earth (planet)
signatures
upwelling water
interactions
crustal contamination

Keywords

  • Large igneous province (LIP)
  • Patagonia
  • Plume-like upwelling
  • Slab interaction
  • Somuncura plateau

Cite this

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The somuncura large igneous province in Patagonia : Interaction of a transient mantle thermal anomaly with a subducting slab. / Kay, S. Mahlburg; Ardolino, A. A.; Gorring, Matthew; Ramos, V. A.

In: Journal of Petrology, Vol. 48, No. 1, 01.01.2007, p. 43-77.

Research output: Contribution to journalArticleResearchpeer-review

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