HR: 09:45h
AN: V31A-08    [Abstracts]
TI: How Deep can be a Dyke?
AU: * Cañón-Tapia, E
EM: ecanon@cicese.mx
AF: CICESE Geology Dept., P.O. Box 434843, San Diego, CA 92143, United States
AB: Magma transport through dykes is a fundamental component of volcanic activity. Due to limited exposure in the field, however, the depth to the magma source that fed a given dyke might remain undeterminable. Based on the width to length ratio determined from horizontal exposures, one could conclude that some dykes might have extended from magma sources 250 km deep to the surface, therefore providing a temporal hydraulic connection between both extremes. On the other hand, dykes might be conceived as buoyant cavities of more or less fixed dimensions that ascend through the lithosphere. In this case, dykes are predicted to have a much more limited vertical extent. Both of these conceptual models serve to explain equally well the existence of deep crust or upper mantle xenoliths in erupted products, as such xenoliths only require fast enough magma ascent rates for their preservation, and this can be achieved in both models. In this work the assumptions made in both conceptual models of a dyke are examined with detail. Although physically plausible ranges for dyke heights are obtained, it is shown that an answer to the question of how deep can be a dyke ultimately resides in a subjective choice of the conceptual model.
DE: 8429 Lava rheology and morphology
DE: 8434 Magma migration and fragmentation
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly