Flood lavas on Earth, Io and Mars

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doi: 10.1144/0016-764904-503
Authors:Keszthelyi, Laszlo; Self, Stephen; Thordarson, Thorvaldur
Author Affiliations:Primary:
U. S. Geological Survey, Astrogeology Team, Flagstaff, AZ, United States
Other:
Open University, United Kingdom
University of Hawaii at Manoa, United States
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 163(2), p.253-264. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2006
Note:In English; illus., incl. 3 tables
Summary:Flood lavas are major geological features on all the major rocky planetary bodies. They provide important insight into the dynamics and chemistry of the interior of these bodies. On the Earth, they appear to be associated with major and mass extinction events. It is therefore not surprising that there has been significant research on flood lavas in recent years. Initial models suggested eruption durations of days and volumetric fluxes of order 107 m3 s-1 with flows moving as turbulent floods. However, our understanding of how lava flows can be emplaced under an insulating crust was revolutionized by the observations of actively inflating pahoehoe flows in Hawaii. These new ideas led to the hypothesis that flood lavas were emplaced over many years with eruption rates of the order of 104 m3 s-1. The field evidence indicates that flood lava flows in the Columbia River Basalts, Deccan Traps, Etendeka lavas, and the Kerguelen Plateau were emplaced as inflated pahoehoe sheet flows. This was reinforced by the observation of active lava flows of ≥100 km length on Io being formed as tube-fed flows fed by moderate eruption rates (102-103 m3 s-1). More recently it has been found that some flood lavas are also emplaced in a more rapid manner. New high-resolution images from Mars revealed "platy-ridged" flood lava flows, named after the large rafted plates and ridges formed by compression of the flow top. A search for appropriate terrestrial analogues found an excellent example in Iceland: the 1783-1784 Laki Flow Field. The brecciated Laki flow top consists of pieces of pahoehoe, not aa clinker, leading us to call this "rubbly pahoehoe". Similar flows have been found in the Columbia River Basalts and the Kerguelen Plateau. We hypothesize that these flows form with a thick, insulating, but mobile crust, which is disrupted when surges in the erupted flux are too large to maintain the normal pahoehoe mode of emplacement. Flood lavas emplaced in this manner could have (intermittently) reached effusion rates of the order of 106 m3 s-1.
Sections:Lunar and planetary studies; Petrology
Subsections:Volcanology
Subjects:Basalts; Cenozoic; Columbia River Basalt Group; Deccan Traps; Earth; Emplacement; Eruptions; Flood basalts; Galilean satellites; Igneous rocks; Interplanetary comparison; Io Satellite; Large igneous provinces; Lava; Lava flows; Lava tubes; Mars; Miocene; Models; Neogene; Pahoehoe; Planets; Satellites; Solar system; Terrestrial planets; Tertiary; Turbulence; Volcanic features; Volcanic rocks; Africa; East Pacific Ocean Islands; Europe; Hawaii; Iceland; Kerguelen Plateau; Namibia; Oceania; Polynesia; Southern Africa; United States; Western Europe; Etendeka flood basalt; Laki flow field
Abstract Numbers:06M/1103
Record ID:2006024991
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London
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