9628575 Vallance This study will focus on the dating and correlation of tephra layers and their association with downstream debris flows and pyroclastic flows with the goal of delineating the postglacial volcanic history of Mount Rainier and the behavior of the volcano during eruptive cycles. It will have as secondary goals the development and refinement of geochemical correlation techniques for andesitic tephras, and the magmatic evolution of the volcano during postglacial time at Mount Rainier volcano. The goals of the project will be met through traditional field methods and through geochemical fingerprinting and correlation techniques. Traditional methods include basic stratigraphy, radiocarbon dating, and component analysis of ferromagnesian minerals. Geochemical fingerprinting will be accomplished by analyzing whole rock and groundmass glass for major and trace elements and by microprobing groundmass glass and ferromagnesian minerals for major and minor elements then applying statistical analysis of similarity and variation coefficients to test possible correlations. The proposed study would greatly improve the hazard assessment at Mount Rainier by synthesizing stratigraphic sequences of past eruptions into genetic packages. Once understood, past eruptions can be used as models for potential behavior at the volcano if it becomes active.
