Magmatic processes that generated the rim andesites of Medicine Lake Volcano, N. California
Author(s)Fuentes, Jocelyn J
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.
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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.
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (pages -).
DepartmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.
Massachusetts Institute of Technology
Earth, Atmospheric, and Planetary Sciences.