Files and links (1)
PDFOpen Access (License Unspecified), Open Access
Dissertation
Insights into the Magmatic System and Degassing Structures of Volcanoes on Bioko Island (Equatorial Guinea) from Fluid Geochemistry and Seismology
Doctor of Philosophy (Ph.D.), Drexel University
Oct 2023
DOI:
https://doi.org/10.17918/00001866
Abstract
The origins of Cameroon Volcanic Line (CVL) are elusive and hotly debated. The vast majority of investigations have been conducted on the continental portion of the line, biasing the interpretations. Bioko Island, Equatorial Guinea, straddles the edge of the continental shelf and represents the transition of the CVL from continental to oceanic crust. This work represents the first in-depth, multidisciplinary investigation of an offshore CVL volcanic system. Here, I employ soil CO₂ surveys, mineral chemistry, Raman spectroscopy and noble gas isotopic analyses of fluid inclusions, and seismic receiver functions to explore the Pico Basile volcanic system on Bioko Island. The results show that surface degassing is controlled by ~35° N striking primary structures of the CVL and shallower secondary structures. Mantle-derived CO₂ ([delta]13C-CO₂ of -3[per mille] vs V-PDB) is the dominant surface gas species followed by thermogenic CH4 ([delta]13C-CH4 of -34.8[per mille] vs V-PDB). Noble gases from surfaces emissions are isotopically similar to those of fluid inclusions (~5 to 6.8Ra), analyses of which indicate fractional equilibrium degassing in the presence of additional radiogenic He from the crust. CO₂ densimetry from Raman spectroscopy reveals a zone of magmatic underplating beneath the Moho at 12-14 km. This is supported by the presence of a low velocity zone (LVZ) of similar depth and thickness suggested by seismic receiver functions. Crustal structures were difficult to resolve in this study, and characteristics of eruptive products imply an absence of shallow (< 1 km) storage and rapid ascent of magma from depth, which has important implications for volcano monitoring.
Metrics
47 File views/ downloads
54 Record Views
Details
- Title
- Insights into the Magmatic System and Degassing Structures of Volcanoes on Bioko Island (Equatorial Guinea) from Fluid Geochemistry and Seismology
- Creators
- Christine Ruth Sealing
- Contributors
- Loÿc Vanderkluysen (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- viii, 96 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES); College of Arts and Sciences; Drexel University
- Other Identifier
- 991021230111704721