Faculty Advisor

Jeffrey, Tepper

Area of Study

Science and Mathematics

Publication Date

Summer 2011


The Cascade Range is a classic example of a continental magmatic arc, a belt of igneous activity resulting from subduction of the oceanic Juan de Fuca plate beneath the western margin of the North American plate. The Cascade arc, which started forming about 38 million years ago, is unique in that extensive uplift and erosion have exposed plutonic and volcanic rocks of similar age. This study will focus on the Mt. Persis area in the North Cascades, where a pluton of the Index batholith is surrounded by near-source volcanic rocks and suggests that the volcano may have originated from the same magma chamber as the batholith. Specific goals of this study are to determine whether the plutonic and volcanic rocks near Mt. Persis are genetically related to each other, and to collect and analyze geochemical data to better understand how and why Cascade arc rocks vary in composition through both space (along the length of the arc) and time (over the past 38 Ma). Examples of parameters that have changed over the last 38 Ma, and that may have affected magma chemistry, include rate of subduction and the thickness of the overlying crust. Combining geochemical data gathered from the Mt. Persis area with data from other studies will allow a better understanding of what processes have caused spatial and temporal changes in the composition of the Cascade arc.


University of Puget Sound

hanson_summer_2011_poster.ppt (3422 kB)
Poster in MS Powerpoint format

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