Physical Sciences and Mathematics Commons^™

Platinum Decoupling From Pge In Peridotitic Sulfides From The St. Elena Ophiolite In Costa Rica, Jessica A. Holm

Theses and Dissertations

The platinum group elements (Os, Ir, Ru, Rh, Pt, Pd) are important petrogenetic tracers of mantle processes and the Re-Os isotope system an important tool for tracing ancient depletion and refertilization processes in the mantle. A key characteristic of these elements is that they are siderophile and chalcophile, and their abundance in the Earth’s mantle is thought to be controlled by sulfides. Existing thermodynamic data suggests that at reducing conditions similar to those found at the early stages of serpentinization, PGE may exist as alloys in the mantle. While numerous studies report on the bulk peridotite PGE and sulfide PGE …

Behavior Of Rare Earth Elements And High-Field Strength Elements During Peridotite - Seawater Interaction, Carl Pasquale Frisby

Theses and Dissertations

Serpentinized abyssal peridotites are evidence for active communication between the Earth’s hydrosphere and the upper mantle, where exchange and retention of both major and trace elements occur. Rare earth elements (REE) and high-field strength elements (HFSE: Ti, Zr, Hf, Nb, Ta) are generally thought of as immobile during serpentinization. In partially serpentinized abyssal peridotites, clinopyroxenes typically retain radiogenic Nd and Hf isotopic signatures that have been used to infer the composition and high temperature processes in the upper mantle. However, bulk rock Nd isotopes in some serpentinized abyssal peridotites less radiogenic values that approach that of seawater, which has been …

Neuro-Fuzzy Classification Of Felsic Lava Geomorphology At Alarcon Rise, Mexico, Christina Hefron Maschmeyer

Theses and Dissertations

The Alarcon Rise is the only submarine oceanic spreading ridge setting where rhyolitic lavas have been found. This intermediate-rate spreading ridge provides a unique natural laboratory for studying the geomorphology of felsic submarine lava flows at oceanic spreading ridges. Seafloor observations of felsic lava indicate the flow morphology differs from typical submarine basaltic lava at the few other oceanic spreading ridges where differentiated compositions have been recorded. Morphologic variation between mafic and felsic lava flows, especially rhyolites, was also observed at Alarcon Rise.

The Monterey Bay Aquarium Research Institute conducted mapping surveys with autonomous underwater vehicle D Allan B. in …