Magmatic Processes

The textures and compositions of volcanic rocks, and the phenocrysts, microlites, and vesicles they contain, provide an important record of volcanic processes that occur prior to and during eruption. Such data provide an important constraint on the temperature and storage pressure of modern volcanic systems, and they provide our only record for older eruptions (e.g. any eruption not monitored using geophysical techniques). I study the textures and compositions of natural rocks and phenocrysts to describe the rates and styles of magma mixing.

Some of the results that have come out this lab recently include:

Magma storage conditions at Santa Maria 1902 dacite PDF
Data for a revised plagioclase-melt hygrometer (Waters and Lange, submitted)
Phase equilibria and plagioclase decompression speedometry in rhyolites (Waters et al., in revision)
Magma storage conditions at Chaos Crags rhyodacite (Erin Quinn, M.S. Thesis)
Controls on magma mixing style PDF
Magma storage and decompression rates for Opala 1500 B.P. rhyolite


Lassen Banded Pumice

I study the textures and compositions of natural rocks and phenocrysts to describe the rates and styles of magma mixing. Link to CTMP paper

Quantifying Magma Mixing

X-ray tomography and numerical modeling can be used to describe magma mixing timescales and lengthscales. Link to CTMP paper

Experimental Petrology

Using equilibrium and disequilibrium experimental petrology I quantify the pre-eruption storage conditions of magmas and the rates at which they decompress (and thus ascend) during eruption. Through constant pressure heating and cooling experiments I am also studying thermal breakdown of phenocrysts and how phenocryst zoning patterns can be related to changes in magma temperature such as might occur during magma mixing.

Experimental Petrology Lab

The lab currently comprises 4 horizontal furnaces with computer-controlled temperature. We use waspalloy cold-seal pressure vessels. By using one furnace and pressure vessel as an actuator, we can run continuous decompression experiments (rather than single- or multi-step decompressions) that cover a broad range of decompression rates (<0.1 MPa/h)