Mechanism of magma mixing at Glass Mountain, Medicine Lake Highland Volcano, California
Mixing of basaltic and rhyolitic magmas at Glass Mountain appears to have been driven by vesiculation of basaltic magma as it intruded a rhyolitic magma chamber. Rapid cooling of basaltic magma formed a mafic foam which floated and became concentrated at the roof of the chamber. Foam-rich lava emerged first during the eruption, and became the hybrid dacite of the distal end of the flow. The chamber is probably a relatively large-volume, long-lived feature, lying within 10 km of the surface beneath the caldera. This mechanism of mixing between silicic magma stored in a crustal chamber and basaltic magma feeding the chamber is controlled by initial water content of basaltic magma, and implies that dry basaltic magma would remain at the base of the chamber. The eastward change from andesitic to bimodal volcanism in this portion of the Cascade Range may be due to an eastward decrease in water content of parental basaltic magmas. 6 figures, 1 table.
- Research Organization:
- Los Alamos Scientific Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5940433
- Report Number(s):
- LA-UR-79-2795; CONF-791080-1
- Country of Publication:
- United States
- Language:
- English
Similar Records
Post-11,000-year volcanism at Medicine Lake Volcano, Cascade Range, northern California
Geologic evidence for a magma chamber beneath Newberry Volcano, Oregon
Related Subjects
580202* -- Geophysics-- Volcanology-- (1980-1989)
BASALT
CALIFORNIA
DATA
DATA FORMS
DENSITY
EXPERIMENTAL DATA
GRAPHS
IGNEOUS ROCKS
INFORMATION
ISOLATED VALUES
LAVA
MAGMA
MIXING
NORTH AMERICA
NUMERICAL DATA
PHYSICAL PROPERTIES
RHYOLITES
ROCKS
USA
VOLCANIC ROCKS
VOLCANOES
WESTERN REGION