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Titre du Document
Petrology and geochronology of basalt breccia from the 1996 earthquake swarm of Loihi seamount, Hawaii : magmatic history of its 1996 eruption
Auteur(s)
GARCIA M. O. ; RUBIN K. H. ; NORMAN M. D. ; ...
Résumé
Samples of basalt were collected during the Rapid Response cruise to Loihi seamount from a breccia that was probably created by the July to August 1996 Loihi earthquake swarm, the largest swarm ever recorded from a Hawaiian volcano. 210Po-210Pb dating of two fresh lava blocks from this breccia indicates that they were erupted during the first half of 1996, making this the first documented historical eruption of Loihi. Sonobuoys deployed during the August 1996 cruise recorded popping noises north of the breccia site, indicating that the eruption may have been continuing during the swarm. All of the breccia lava fragments are tholeiitic, like the vast majority of Loihi's most recent lavas. Reverse zoning at the rim of clinopyroxene phenocrysts, and the presence of two chemically distinct olivine phenocryst populations, indicate that the magma for the lavas was mixed just prior to eruption. The trace element geochemistry of these lavas indicates there has been a reversal in Loihi's temporal geochemical trend. Although the new Loihi lavas are similar isotopically and geochemically to recent Kilauea lavas and the mantle conduits for these two volcanoes appear to converge at depth, distinct trace element ratios for their recent lavas preclude common parental magmas for these two active volcanoes. The mineralogy of Loihi's recent tholeiitic lavas signify that they crystallized at moderate depths (∼ 8-9 km) within the volcano, which is approximately 1 km below the hypoc
Editeur
Springer
Identifiant
ISSN : 0258-8900 CODEN : BUVOEW
Source
Bulletin of volcanology (Print) A. 1998, vol. 59, n° 8, pp. 577-592 [Illustrations : Tableau] [bibl. : 1 p.1/4]
Langue
Anglais
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