Persistent Link:
http://hdl.handle.net/10150/555561
Title:
Time Scales of a Geothermal System from Actinolite Fe-Mg Zoning
Author:
McIntire, Michael Zackery
Issue Date:
2014
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Volume diffusion provides a mechanism to assess the duration, and hence the timescales of thermal events. In this study, interdiffusion of Fe and Mg across a sharply zoned interface in actinolite was studied to determine timescales of hydrothermal activity associated with the Santos deposit in Punta del Cobre, Chile. Petrographic analysis to identify textures, mineral relations, and mineral orientation was conducted on several thin sections of drill core from the Santos deposit. Mineral phase relations, fluid inclusion results from the nearby Candelaria deposit, and comparison with the modern Salton Sea Geothermal System allow estimation of the maximum temperatures during ore formation. SEM analyses were performed on the samples to identify strongly zoned actinolite crystals. Microprobe stage scan analyses were conducted to create a diffusion profile and determine the diffusion coefficient and time. Although there is little known about diffusion in actinolite, orthopyroxene (OPX) was chosen as a proxy because it is a chain silicate and has Fe-Mg diffusion in both of the M sites and thus broadly analogous to actinolite. Using OPX diffusion coefficients maximum timescales from 10⁴ to 10⁶ years for maximum temperatures of 350 to 450˚C. These times match data from some modern geothermal systems.
Type:
text; Electronic Thesis
Degree Name:
B.S.
Degree Level:
bachelors
Degree Program:
Honors College; Geology
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleTime Scales of a Geothermal System from Actinolite Fe-Mg Zoningen_US
dc.creatorMcIntire, Michael Zackeryen
dc.contributor.authorMcIntire, Michael Zackeryen
dc.date.issued2014en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.abstractVolume diffusion provides a mechanism to assess the duration, and hence the timescales of thermal events. In this study, interdiffusion of Fe and Mg across a sharply zoned interface in actinolite was studied to determine timescales of hydrothermal activity associated with the Santos deposit in Punta del Cobre, Chile. Petrographic analysis to identify textures, mineral relations, and mineral orientation was conducted on several thin sections of drill core from the Santos deposit. Mineral phase relations, fluid inclusion results from the nearby Candelaria deposit, and comparison with the modern Salton Sea Geothermal System allow estimation of the maximum temperatures during ore formation. SEM analyses were performed on the samples to identify strongly zoned actinolite crystals. Microprobe stage scan analyses were conducted to create a diffusion profile and determine the diffusion coefficient and time. Although there is little known about diffusion in actinolite, orthopyroxene (OPX) was chosen as a proxy because it is a chain silicate and has Fe-Mg diffusion in both of the M sites and thus broadly analogous to actinolite. Using OPX diffusion coefficients maximum timescales from 10⁴ to 10⁶ years for maximum temperatures of 350 to 450˚C. These times match data from some modern geothermal systems.en
dc.typetexten
dc.typeElectronic Thesisen
thesis.degree.nameB.S.en
thesis.degree.levelbachelorsen
thesis.degree.disciplineHonors Collegeen
thesis.degree.disciplineGeologyen
thesis.degree.grantorUniversity of Arizonaen
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