Low pressure fractionation in arc volcanoes: an example from Augustine Volcano, Alaska

Augustine Volcano is situated between the Cook and Katmai segments of the Eastern Aleutian Volcanic Arc. Eruptions are characterized by early vent-clearing eruptions with accompanying pyroclastic flows followed by dome-building and more pyroclastic flows. Bulk rock chemistry of historic and prehistoric lavas shows little variability. Comparison of glass compositions with experimental results is consistent with low pressure fractionation of a relatively dry silicate melt. Disequilibrium of amphiboles and the evolved nature of glasses indicate that shallow level fractionation plays a significant role in the evolution of Augustine magmas. This model is consistent with a shallow magma chamber inferred from geophysical models of the Augustine system and also with its simple, predictable eruption pattern.

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Citation Date 1985-08-26T17:37:41Z

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Original ID 5b892059f36080b5b0b519641458319d
Index Date 2014-09-22T15:22:23Z
Original Format ISO-USGIN
Original Version 1.2


Name Daley, E.E.
Position missing
Organization University of Alaska, Fairbanks
Email Missing
Name Swanson, S.E.
Position missing
Organization University of Alaska, Fairbanks
Email Missing

Geographic Extent

North Bound 59.575537668146
South Bound 59.155681138395
East Bound -152.98275108889
West Bound -153.91109581545