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Roof-rock contamination of magma along the top of the reservoir for the Bishop Tuff

Journal of Volcanology and Geothermal Research

By:
, , and
DOI: 10.1016/0377-0273(95)00026-7

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Abstract

The Bishop Tuff, a Quaternary high-silica rhyolite in east-central California, is widely considered the type example of a vertically and monotonically zoned pyroclastic deposit that represents zoning in the source magma reservoir, inverted during the process of pyroclastic emplacement. However, the deposit of plinian pumice, which forms the base of the Bishop Tuff and represents the initial 10% or so of all magma erupted during the event that produced the Bishop Tuff, contains features at odds with monotonic zoning for the reservoir. Relative to overlying ignimbrite, the plinian deposit contains a reversal in trace-element zoning. The data have been previously interpreted as due to processes of chemical fractionation and evolution operating within a magma system closed to chemical interactions with its roof rocks. However, it is suggested here that the reversed zoning and other above-noted features can be explained equally well as consequences of minor assimilation of roof rocks into a magma reservoir that was erupted from the top down. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Roof-rock contamination of magma along the top of the reservoir for the Bishop Tuff
Series title:
Journal of Volcanology and Geothermal Research
DOI:
10.1016/0377-0273(95)00026-7
Volume
69
Issue:
3-4
Year Published:
1995
Language:
English
Publisher:
Elsevier
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Volcanology and Geothermal Research
First page:
187
Last page:
195