Mineral textures in the Auckland Volcanic Field: Insights into ascent processes.
Date
2023
Authors
Coker, J. L.
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Abstract
The Auckland Volcanic Field, a prominent monogenetic basaltic field, is characterized by rapid magma ascent from source to surface, yielding a landscape of diverse volcanic morphologies. Despite being extensively studied, the fundamental processes governing this field remain largely enigmatic. This study aims to shed light on these mysteries by scrutinizing mineralogical textures and chemistry at a scale representative of the entire volcanic field.
To achieve this, we employed advanced techniques, including Scanning Electron Microscope (SEM) image analysis, Electron Microprobe chemical analysis, equilibrium testing, and thermobarometry. Through these methods, we scrutinized various minerals and identified compelling evidence suggesting fluctuations in magma ascent rates. Notably, we observed variable normal zoning rates in olivine, oscillatory zoning in clinopyroxenes, and the presence of lamellae exsolution, surrounded by unexsolved crystallization of Fe-Ti oxides. These mineralogical features offer crucial insights into the dynamic processes taking place during the ascent of magma beneath the Auckland Volcanic Field.
The implications of these findings extend beyond geological curiosity. Understanding the changes in magma ascent rates carries significant implications for the forecasting and early detection of moving magma beneath Auckland. If magmas can be identified during slower ascent stages, this knowledge could serve as an essential precursor to the potentially hazardous rapid ascent phase. This insight is not only valuable for understanding the volcanic field's monogenetic nature but also for enhancing the safety and preparedness of the Auckland region in the face of volcanic activity.
In conclusion, our research unveils critical mineralogical evidence of variable ascent rates within the Auckland Volcanic Field, enriching our understanding of this complex geological system. Furthermore, the potential implications for volcanic hazard mitigation underscore the practical significance of this study, as it has the potential to improve volcanic forecasting systems and protect the well-being of the Auckland community.
School/Discipline
School of Physical Sciences
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Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
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