Abstract by Levi De Crescenzo
Levi De Crescenzo
The History of Yellowstone Lavas: X-Ray Diffraction in the Kimberly Core
The Kimberly Core represents a series of igneous deposits along the Snake River Plain, which tracks the movement of the North American plate over the Yellowstone hotspot. The core is made of rhyolite and basalt lavas and tuffs that span 1,982 m below the surface. The Kimberly Member, which ranges from depths of 427-610 m, consists of brecciated rhyolites with some vitrophyric and perlitic textures. Anomalously high δ18O values are found in altered parts of this member as well as a general increase in δ18O in the core with decreasing depth. Initial examination suggested that clay minerals could explain these isotopic values. X-ray Diffraction (XRD) of the Kimberly member found no evidence of clay minerals but revealed large amounts of secondary zeolite minerals, but the presence of zeolites is consistent with the highest δ18O, as zeolites preferentially incorporate 18O. XRD was also useful in identifying the mineralogy of magmatic phenocrysts and devitrified groundmass but the increasing δ18O through the lower member remains under investigation.