The Clarno Formation is a series of volcanic, volcaniclastic, and related intrusive rocks located in central Oregon. It is the westernmost extent of a broader Eocene magmatic belt that covers much the western United States. The magmatic belt stretches eastward from Oregon to western South Dakota, and from the Canadian...
Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop...
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2. Magma evolution and dynamics in a continental caldera-relatedmagma system:
The 3.49 Ma
Three broadly interrelated problems of critical significance to the proper interpretation of melt inclusion (MI) data are addressed in this thesis. The first issue, the petrogenesis of anorthitic plagioclase phenocrysts in MORB lavas, has relevance due to the presence of numerous MI in many high-An feldspars. This problem was addressed...
Inheritance from pre-existing mantle domains and fluid and melt contributions from active subduction together produce the geochemical signatures of mantle-derived arc basalts. In this context, this work evaluates the evolution of Cascadia mantle sources by documenting the isotopic and compositional characteristics of primitive basalts along a transect across the Eocene-Oligocene...
This dissertation reports on four related, though separate projects. The first project details the process of carrying out a digitally augmented soil mapping (DSM) effort alongside an ongoing survey in Oregon's Ochoco National Forest (ONF) using a Random Forest algorithm. The second chapter describes a initial soil survey in Oregon's...
The Pastos Grandes Caldera Complex (PGCC) in southwest Bolivia has produced two large-volume (≥800 km³ DRE) dacite ignimbrites from a nested caldera source over a period of 5.5 Myr. In addition to the large-volume ignimbrites, a small-volume ignimbrite shield and post-climactic lavas define this composite system. Based on detailed field...
The 4.59-4.18 Ma Caspana ignimbrite, found within the Altiplano-Puna Volcanic Complex (APVC), is the result of an ~8km3 eruption that took place during the Neogene Ignimbrite Flare-up in the N. Chilean Andes. While most of the eruptions during this flare up are large, monogenetic eruptions, the Caspana that is characterized...
We report new geochemical data for boninites and backarc basin-type basalts recovered from the northern termination of the Tonga trench and Lau Basin. Boninitic pillow lavas, ranging from high-Mg compositions to andesites and dacites, have been erupted within large submarine volcanic edifices (calderas and volcanoes) associated with active rifting of...
New seafloor mapping and sampling demonstrates that the eruption of the high-Ca boninites is clearly associated with rifting of the northern Tonga ridge and the northern Lau Basin at the northern termination of the Tonga Trench. There is very strong evidence for OIB plume related mantle sources involved in the...