Petit-spot lava fields off the central Chile trench induced by plate flexure

Naoto Hirano*, Shiki Machida, Natsue Abe, Tomoaki Morishita, Akihiro Tamura, Shoji Arai


研究成果: Article査読

29 被引用数 (Scopus)


In 2009, petit-spot submarine volcanoes were discovered off the oceanward slope of the central Chile trench, offshore from Valparaiso, Chile, at around 33°S. Ar-Ar dating of mugearite and alkali-basalt from the volcanoes yields ages of 10 11 ±0.22 Ma and 6.69 ±0.88 Ma, respectively. Back-calculations of plate motion along the present absolute movement direction of the Nazca Plate, conducted using the Ar-Ar age data, indicate that eruption occurred above a zone of plate flexure The back-calculation results suggest that the mugearite was erupted at a flexural arch prior to arrival at the active site of the Juan Fernandez hotspot. In contrast, the alkali-basalt was erupted on a plate flexure at a site of interaction between a flexural moat and an outer-rise area, where the source material was probably influenced by the Juan Fernandez hotspot The geochemistry of the lavas supports this interpretation because the concentration ratios of various rare earth and other trace elements in the mugearite are different from those of the alkali-basalt and Juan Fernandez hotspot lavas. Consequently petit-spot melts could reflect the composition of source materials below the plates at sites of plate flexure.

ジャーナルGeochemical Journal
出版ステータスPublished - 2013

ASJC Scopus subject areas

  • 地球化学および岩石学
  • 地球物理学


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