Physical Sciences and Mathematics Commons^™

A Petrologic Study Of The Teanaway Basalt: Eocene Slab Window Volcanism In Central Wa, Liz Roepke

Summer Research

The Teanaway Basalt (TB) includes subaerial basalt to andesite flows, mafic to felsic tuffs, and rhyolite domes in the Central Cascades of Washington State. These volcanics overlie the extensive ~47 Ma Teanaway Dike Swarm (TDS) that cuts the underlying Swauk Formation. Samples were collected from 3 main localities: Easton Ridge (ER) in the west, Liberty Ridge (LR) in the east, and the Middle Fork of the Teanaway River (MF) in the center.

The bimodal TB consists predominantly of basaltic andesite and andesite (45.3–63.1 wt% SiO₂) with subordinate rhyolite (75.9–79.4 wt% SiO₂). The mafic rocks classify as …

A Structural And Paleomagnetic Analysis Of The Basalts Of Summit Creek, Anne Fetrow

Summer Research

This study is a detailed analysis of the structural geology and paleomagnetism of the Basalts of Summit Creek. Located southeast of Mount Rainier, this section of layered basaltic flows formed during the Eocene Epoch (55 to 45 Ma). The exact origin of the Basalts of Summit Creek is unknown, but there appears to be a growing connection between the Basalts of Summit Creek and the Crescent Basalts, which are Eocene flood basalts located on the Olympic Peninsula (Clark, 1989). This study attempts to provide a greater understanding of the emplacement and deformation of the Basalts of Summit Creek and any …