Magmatic processes that generated the rim andesites of Medicine Lake Volcano, N. California

This paper characterizes the compositionally distinctive high-Na andesite lavas at Medicine Lake Volcano that erupted at ~100 ka and that built most of Medicine Lake's caldera. These high-Na lavas define a compositional trend that formed by fractional crystallization in a shallow magma chamber (~ 4 to 8 km). Petrologic evidence indicates pre-eruptive H20 contents of 2 to 4 wt.% H20 over a temperature range of 1070 to 900 C. Oxygen fugacity recorded in coexisting spinel and rhombohedral oxides varies from NNO (Nickel - Nickel Oxide) to NNO 0.7 log units. Experiments performed at 1 kbar - H20 saturated conditions at the NNO buffer on a primitive andesite reproduce most of the major element compositional variability exhibited in the high-Na lavas.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2012

Author dc:creator

• Fuentes, Jocelyn J

Advisor dc:contributor.advisor

• Timothy Grove.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/114354

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/114354