The ~1000 km3 Peach Spring Tuff (PST) is the product of an 18.8 Ma supereruption from Silver Creek caldera, southern Black Mountains, AZ (Ferguson et al 2013). Five zones are recognized in thick outflow sections of the ignimbrite near Kingman, AZ, based on welding characteristics and phenocryst, pumice, and lithics abundances. The lower four zones are uniformly high-silica rhyolite (HSR) (74-76 wt% SiO2; Pamukcu et al 2013; Barry et al 2015). Phenocryst content increases gradually upward from ~2% in the lowest zone to ~20% modally in the fourth zone (Ferguson & Cook, 2015), and then rapidly upward into the capping fifth zone, a densely welded, phenocryst-rich (~35%) trachyte (65-69 wt% SiO2) whose fiamme match those in intracaldera PST in texture and composition (Pamukcu et al 2013). Zone 5 fiamme are characterized by high Ba, Sr and Zr concentrations, compared to the highly evolved chemical signature of the HSR outflow. Phenocrysts in intracaldera and outflow trachytic pumice are large and exhibit evidence of resorption and reaction. Glasses in the trachyte are extremely enriched in elements consistent with the partial dissolution of the phenocryst assemblage. Previous elemental and isotopic data, plus new elemental data, support a model of the PST reservoir as a single, relatively simple, vertically stratified chamber with a crystal-rich base and massive, high-silica, crystal-poor upper zone (Frazier, 2013; McDowell et al 2016). Outflow and intracaldera trachyte represent the crystal-rich cumulate base proposed to have been partially remelted and remobilized, via injection of a hot mafic magma.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07212017-173225 |
| Date | 27 July 2017 |
| Creators | Foley, Michelle Lee |
| Contributors | Calvin F. Miller, Guilherme A.R. Gualda, Simon A.F. Darroch |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07212017-173225/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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