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Full-Text Articles in Geology
Using Trace Element Concentrations In Volcanic Ash To Elucidate Magma Sources To Koma Kulshan’S (Mount Baker) Most Recent Explosive Eruption – The 6.7 Ka Ba (Black Ash) Tephra, Stone Machel
Geology Graduate and Undergraduate Student Scholarship
Koma Kulshan (Mount Baker) is an active stratovolcano in the northern Washington Cascades. Kulshan’s most recent magmatic eruption at 6.7 ka was explosive, producing the ~0.2 km3 BA tephra (black ash) from the edifice (Scott et al. 2019). Comprehensive geochemical data for the BA tephra were previously limited to major elements from one whole rock lapillus (silicic andesite) and several in situ glass analyses (dacite), despite being Kulshan’s most voluminous Holocene tephra. Here, I present the first extensive major and trace element study of the pyroxene- and plagioclase-bearing BA tephra glass to determine magma source and eruption processes. My …
Shared Roots: A Geochemical Investigation Of Basaltic Andesites To Understand Magmatic Cogenesis At The Middle Sister And South Sister Volcanoes, Central Oregon, Sean Francis Halstead
Shared Roots: A Geochemical Investigation Of Basaltic Andesites To Understand Magmatic Cogenesis At The Middle Sister And South Sister Volcanoes, Central Oregon, Sean Francis Halstead
WWU Honors College Senior Projects
The Middle Sister and South Sister volcanoes, near Bend, Oregon, are overlapping, active Cascade Arc stratovolcanoes which share a complex, contemporaneous eruptive history. This history is characterized by an extreme compositional diversity of lavas erupted in alternating phases of high activity from one neighboring volcano to the other, with both vents producing material ranging from basaltic andesite to rhyolite. This system is understood to be predominantly fed by basaltic andesites fractionated from partial mantle melts within the lower crust, but magma compositions are additionally impacted by mixing, assimilation, and crustal contamination while in transit to the surface. Thus, the subterranean …
Using Crystal Zoning, Thermobarometry, And Melts To Elucidate Koma Kulshan’S (Mt. Baker) Transcrustal Magma Storage System, Northern Cascade Arc, Brendan Garvey
Using Crystal Zoning, Thermobarometry, And Melts To Elucidate Koma Kulshan’S (Mt. Baker) Transcrustal Magma Storage System, Northern Cascade Arc, Brendan Garvey
WWU Graduate School Collection
Koma Kulshan (Mt. Baker) is classified as a high-threat volcano due to its past eruptive history and its proximity to populations, yet its eruptive products are understudied. Combining mineral chemistry from complexly zoned crystals with thermobarometry and thermodynamic modeling (MELTS) is a powerful way to provide constraints on magmatic processes beneath an active volcano. Up to four populations each of pyroxene, plagioclase, and olivine occur as phenocrysts and crystal clusters in the youngest (9.8 ka) lava flow at Koma Kulshan and represent four co-crystallizing assemblages derived from distinct magmas. These co-crystallizing assemblages are defined by petrologic observations and mineral chemistry …