Détail de la notice
Titre du Document
Emplacement of continental flood Basalt lava flows
Auteur(s)
SELF S. ; THORDARSON T. ; KESZTHELYI L. ; ...
Résumé
We propose that continental flood basalt (CFB) lavas were predominantly emplaced as inflated compound pahoehoe flow fields via prolonged, episodic eruptions. Our most detailed observations come from the ∼14,7 Ma Roza flow field of the Columbia River Basalt (CRB) Group. The Roza flow field seems to be typical of many flood basalt lavas. Individual flows show a wide range of pahoehoe surface features and a three-part internal structure in vesicularity and other textural parameters. This three-fold division into an upper crust, core, and basal crust appears to be diagnostic of the inflation process and is ubiquitous in basaltic lava flows over a remarkable range of sizes. The pahoehoe surface features and indications of inflation are inconsistent with rapid emplacement of these lava flows. Instead, we interpret the observations to imply that the Roza, and other CFB flows, were emplaced over an extended period of time. From the thickness of the upper crust, which we suggest formed while the flow was actively inflating, and an empirical expression for the rate of crust growth of Hawaiian inflated sheet flows, we estimate that individual Roza flows were emplaced over 5 to 50 months and that the Roza flow field was constructed over a period of 6 to 14 years. However, even with this longer eruption duration, the average lava effusion rate of ∼4000 m3/s is similar to that of the highest-effusion-rate eruption in recorded history (the 1783-4 Laki eruption in Iceland). Our obs
Editeur
American Geophysical Union
Identifiant
ISSN : 0065-8448 CODEN : GPMGAD
Source
Geophysical monograph A. 1997, vol. 100, pp. 381-410 [Illustrations : Tableau] [bibl. : 3 p.1/4]
Langue
Anglais
Pour les membres de la communauté du CNRS, ce document est autorisé à la reproduction à titre gratuit.
Pour les membres des communautés hors CNRS, la reproduction de ce document à titre onéreux sera fournie sous réserve d’autorisation du Centre Français d’exploitation du droit de Copie.

Pour bénéficier de nos services (strictement destinés aux membres de la communauté CNRS (Centre National de la Recherche Scientifique), de l'ESR français (Enseignement Supérieur et Recherche), et du secteur public français & étranger) :