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Petrology Of The Eocene Goble Volcanics, Southwest Washington: An Early Phase Of The Cascade Arc, Clara Phipps, Jeffrey H. Tepper
Petrology Of The Eocene Goble Volcanics, Southwest Washington: An Early Phase Of The Cascade Arc, Clara Phipps, Jeffrey H. Tepper
Summer Research
The Eocene Goble Volcanics (GV), comprised of >1000 km2 of subaerial lavas and tuffs, are one of the most voluminous igneous formations in SW WA. Whole rock K-Ar ages of 45 to 32 Ma (Beck and Burr, 1979) suggest these rocks are an early expression of the Cascade arc, but their location is anomalous, lying between oceanic Crescent Fm basalts of the Siltezia terrane to the west and younger arc rocks to the east. The goals of this research are to determine the chemical and Sr-Nd isotopic traits of the GV and better establish the tectonic setting in which …