Physical Sciences and Mathematics Commons^™

Comparative Geochemical Analysis Of Recent Volcanic Flows On Barva Volcano, Costa Rica, Julie Coulombe

Masters Theses

ABSTRACT

Barva Volcano is a dormant stratovolcano in the Cordillera Central region of Costa Rica, rising above the capital city of San Jose with a population of 347,000. Barva’s recent inactivity and extensive forestation have resulted in fewer investigations of its composition, petrogenesis, and eruptive history. The objective of this research is to analyze the geochemical data from several of the most recent lava flows, evaluate variability between eruptive units, and ascertain physical conditions within the Barva magma storage region. The data collected in this study helps constrain the geochemistry of units seen in the quarry and provides information regarding …

Multiple Generations Of Phlogopite In An Alnöite Diatreme: Insights Into The Petrogenesis Of The Avon Alkaline Igneous Province, Missouri, Nathan Gregory Limbaugh

Masters Theses

“Alkaline Ultramafic Carbonatite (AUC) complexes, although rare, are valued for diamonds and REEs, and as windows into subcontinental and mantle processes as recorded by rock fabrics, mineral spatial relationships, and mineral compositions. We report specifically on olivine and phlogopite petrographic relationships and compositions from the Devonian alnoite diatreme-facies of the Avon Alkaline Igneous Province, Missouri. The diatreme alnoite is a mixture of domains of olivine magmaclasts (OM) set in a crystal-rich melilite matrix. OM are highly fractured, serpentinized olivine pseudomorphs with variable amounts of pristine olivine fragments. Larger olivine domains typically exhibit clear crystal faces and irregular “channels” indicative of …

Petrogenesis And Concentric Zonation Of The Belchertown Intrusive Complex, West-Central Massachusetts, Karen June Van Wagner

Masters Theses

The Belchertown Intrusive Complex is a ~164 km2 Devonian pluton that intruded Paleozoic metasedimentary and metavolcanic rocks in west-central Massachusetts. Intrusion of the pluton was synchronous with Acadian deformation (Ashwal, 1974). The complex is concentrically zoned, with a core of orthopyroxene-biotite monzodiorite, a middle zone of clinopyroxene-hornblende-biotite granodiorite, and an outermost zone of hornblende-biotite granodiorite. Zoning from a more to less hydrous mineral suite from the outside to the inside of the pluton led Ashwal (1974) to suggest that metamorphic hydration most strongly affected the outermost zones of the complex. Basaltic inclusions occur most commonly near the edges of …