Thesis
Petrogenesis of Mount Taranaki tephras
University of Iowa
Master of Science (MS), University of Iowa
Autumn 2023
DOI: 10.25820/etd.007007
Abstract
Mt. Taranaki is an andesitic stratovolcano in Aotearoa New Zealand with a 30 kyr highresolution tephra deposition record. Previous studies have identified temporal variation in glass and titanomagnetite compositions within these tephras for the purpose of tephrostratigraphy, but their petrogenetic interpretation has so far been limited. In this study, we examined the variation in temperature and oxygen fugacity in the last 30 kyrs of Mt. Taranaki eruptions using new titanomagnetite-based methods and identified two possible large eruptions c. 7 ka and 13 ka that are not as easily identified by phase compositions alone. In addition, trace element geochemistry of titanomagnetite and glass, as well as thermobarometry, oxybarometery, and chemometry of amphibole, and thermobarometry of clinopyroxene are used to elucidate the changes within the Mt. Taranaki transcrustal magmatic system across the most recent (c. 3 ka) major compositional shift. The estimated equilibrium melt composition and temperatures for all phases show consistent correlation and shifts in these intensive parameters across the 3 ka transition indicating the magmatic plumbing system is recharging after a major eruption. Recent eruptions are sourced from hotter, less evolved melts residing at greater depths than the preceding eruptions.
Details
- Title: Subtitle
- Petrogenesis of Mount Taranaki tephras
- Creators
- Rachel Lauren Smith
- Contributors
- David W. Peate (Advisor)C. Tom Foster (Committee Member)Valerie Payre (Committee Member)Ingrid Ukstins (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Geoscience
- Date degree season
- Autumn 2023
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.007007
- Number of pages
- xxi, 238 pages
- Copyright
- Copyright 2023 Rachel Lauren Smith
- Language
- English
- Date submitted
- 12/02/2023
- Description illustrations
- Illustrations, tables, graphs, charts
- Description bibliographic
- Includes bibliographical references (pages 162-172).
- Public Abstract (ETD)
Mt. Taranaki is a volcano in Aotearoa New Zealand whose eruption record has been carefully age dated over a period spanning the last 30,000 years. Previous investigations have focused on correlating the eruptive products, called tephras, from one location to another. This paper uses the chemical composition of minerals within the tephras to estimate the temperature, pressure, redox conditions, and water content of the magma they came from before they were erupted. This information indicates Mt. Taranaki’s magma plumbing system has recharged with hot magma after a major eruption 3,300 years ago. Recent eruptions come from these hotter magmas which reside at greater depths than the magmas that generated the older eruptions.
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984546848702771
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