The Plumbing Systems and Parental Magma Compositions of Shield Volcanoes in the Central Oregon High Cascades as Inferred from Melt Inclusion Data
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Date
2012
Authors
Mordensky, Stanley
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Journal ISSN
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Publisher
University of Oregon
Abstract
Long-lived and short-lived volcanic vents often form in close proximity to one another. However, the processes that distinguish between these volcano types remain unknown. Here, I investigate the differences of long-lived (shield volcano) and short-lived (cinder cone) magmatic systems using two approaches. In the first, I use melt inclusion volatile contents for shield volcanoes and compare them to published data for cinder cones to investigate how shallow magma storage conditions differ between the two vent types in the Oregon Cascades. In the second, I model the primitive magmas that fed shield volcanoes and compare these compositions to those of nearby cinder cones to determine if the volcanoes are drawing magma from the same sources.
The volatile concentrations suggest that long-lived and short-lived magmatic plumbing systems are distinct. Modeling of parental magmas and differentiation processes further suggest that long-lived and short-lived volcanoes have erupted lava from the same mantle magma source.
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Keywords
Belknap, Degassing, Magma, Mount Washington, North Sister, Shield Volcano