Experimental Insights into the Formation of High-Mg Andesites in the Trans-Mexican Volcanic Belt
Loading...
Date
2010-06
Authors
Weber, Rachel Maria, 1975-
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
High-Mg basaltic andesites and andesites occur in the central
Trans-Mexican Volcanic Belt, primarily in the region south of Mexico
City, and their primitive chemical characteristics suggest equilibration
with mantle peridotite. These lavas may represent either slab melts that
re-equilibrated with peridotite during ascent or hydrous partial melts of a
peridotite source. I have experimentally mapped the liquidus mineralogy
for a high-Mg andesite from the Pelagatos cinder cone as a function of
temperature and H20 content over a range of mantle wedge pressures.
The results,concur with a published thermo barometer for peridotite
melting and suggest that this composition could only be in equilibrium
with a harzburgite residue at relatively high water contents and low
pressures and temperatures. However, numerically adjusting the composition fo r equilibrium with more refractory mantle (Fo92) shifts
these conditions to lower water content s and higher pressures and
temperatures near where geodynamic models indicate peak mantle
wedge temperatures.
Description
x, 86 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
Keywords
Andesite -- Mexico -- Transverse Volcanic Range, Transverse Volcanic Range (Mexico)