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Catastrophic isotopic modification of rhyolitic magma at times of caldera subsidence, Yellowstone plateau volcanic field.

Journal of Geophysical Research

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Abstract

This Wyoming volcanic field has undergone repeated eruption of rhyolitic magma strongly depleted in 18O. Large calderas subsided 2.0, 1.3 and 0.6 m.y. ago on eruption of ash-flow sheets. More than 60 other rhyolite lavas and tuffs permit reconstruction of the long-term chemical and isotopic evolution of the silicic system. Narrow delta 18O ranges in the ash-flow sheets contrast with wide delta 18O variation in post-caldera lavas. The earliest post-collapse lavas are 3-6per mille lighter than the preceding ash-flow sheets. The 18O depletions were short-lived events that immediately followed caldera subsidence and sequences of post-caldera lavas record partial recovery toward pre-caldera delta 18O values. Contemporaneous extra-caldera rhyolites show no effects of the repeated depletions. Although some contamination by foundering roof rocks seems to be required, water was probably the predominant contaminant.-W.H.B.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Catastrophic isotopic modification of rhyolitic magma at times of caldera subsidence, Yellowstone plateau volcanic field.
Series title:
Journal of Geophysical Research
Volume
89
Issue:
B10
Year Published:
1984
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research
First page:
8339
Last page:
8369
Number of Pages:
31