An Overview
Program: RESESS Boulder
Major: Geology and Geography
Academic Affiliation: State University of New York at Oneonta
Mentors: Dr. Ellen Alexander
Biography
Zulliet is a rising senior at State University of New York College at Oneonta and is pursuing a career in geology. Zulliet is a first generation student who became inspired by the geosciences through an earth science class she took in highschool. Coming from the city, she had little to no exposure to nature and became really interested in geology when she went to a suburban college where she was able to explore her surroundings. She soon thereafter expressed interest in volcanology where she pursued research internships at UNAVCO and has been a RESESS intern for two years now. This summer Zulliet will be investigating the changes in crustal density of the Colorado Plateau triggered by the syn-Laramide hydration.
Abstract
2020- Newly digitized structural data from the southern Appalachians and comparisons to subsurface anisotropy from seismic stations
Seismic anisotropy in rocks is the variation of velocity by the direction of passage of the wave. This phenomenon has the potential to be exploited as an imaging tool for exploring the subsurface structure of a landmass. We investigate this phenomenon and the nature of southern Appalachian seismic fabric, specifically targeting the Greenville 1×2 degree quadrangle which spans the Georgia-South Carolina border and lies within the Blue Ridge and Inner Piedmont. The quadrangle also encompasses the locations of several NSF EarthScope USArray (TA) and Flexible Array (SESAME) seismic stations. Digitization of 4 fabric types from the published geologic quadrangle map (bedding, foliation, lineation, and mylonite) was conducted using GeolMapDataExtractor. Subsets of these data were then selected within a 10 km radius of every seismic station and evaluated using stereonet software and ArcGIS Pro. We compared the strikes of mapped planar fabrics to strikes of dipping subsurface crustal interfaces or foliation as inferred from receiver functions to strikes of hexagonal symmetry planes from modeled seismic anisotropy. We conclude that foliation is the largest fabric contributor to the preserved subsurface geologic structure.
2021- Impact of Metasomatism on Colorado Plateau Lower Crustal Density: Insights from Xenoliths from the Moses Rock and Mule Ear Diatremes, Navajo Volcanic Field
The Colorado Plateau has abnormally high topography, with 2 km of post-Cretaceous surface uplift that cannot be explained from shortening during the Laramide orogeny alone. Among several previously proposed mechanisms is a syn-Laramide deep crustal hydration event with fluids potentially sourced from the subducted Farallon slab. The resulting metasomatic alteration could have decreased crustal density, which would result in isostatic uplift and contribute to the excess elevation increase. Lower crustal xenoliths provide important constraints on modern lower crustal conditions, and those from the Navajo Volcanic Field (central Colorado Plateau) contain a petrologic record of lower crustal hydration and associated retrograde metamorphism. Four metasomatized xenoliths from the Moses Rock and Mule Ear diatremes were used to construct pre- and post- hydration density models for discrete lithologies at lower crustal P and T conditions. Density is estimated to have changed by ca. +0.3% to -6.9% with hydration, dependent on lithology and estimated retrograde reactions during hydration. Lithology-dependent changes in density with hydration have consequences for estimating related uplift, and imply better constraints are needed on the lithological makeup of the Colorado Plateau lower crust.