2015


Crystal Burgess

Crystal Burgess


Years participated in RESESS:
2015


Poster
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An Overview

Major: Geology
Academic Affiliation: Alfred University
Research Mentor: Kathryn Snell
Communications Mentor: Karen Alley


Biography

Crystal grew up in New York City, New York. Her passion in geoscience began on a class camping trip in the 7th grade, where learning how flint can be used to start a fire sparked her interest in rocks and their applications. Since then she has focused her interests on soil science and hydrology. She hopes to contribute to these fields by filling in gaps and challenging discrepancies in existing research. For her RESESS project, Crystal is examining whether carbonates in fossilized soils from the Meade Basin, Kansas, have been chemically altered after original soil formation. Because these carbonates hold clues about past environmental conditions, her results will be combined with other data to help interpret environmental impacts on the evolution of rodents in the region.


Abstract

Detection of Diagenesis in Paleosol Carbonate Nodules Using Optical and Cathodoluminescence Microscopy

This study is part of a project evaluating the environmental conditions that affected the evolution of rodent fauna in the Meade Basin, Kansas during the Miocene-Pleistocene. Prior to this study, a suite of isotopic analyses was measured in paleosol carbonates that were previously collected from the region. The stable isotopic values of these pedogenic carbonates can be used to track changes in the relative abundance of plants that used C3 photosynthetic pathway versus C4. However, diagenetic events may change the chemical composition of a carbonate's isotopic signature, making the isotope values a potentially unreliable reflection of paleoclimatic conditions. To investigate this, we used Cathodoluminescence  (CL) and optical microscopy to determine the extent of diagenetic alteration in carbonate nodules collected from the Meade Basin. The CL and petrographic images reveal a range in the extent of preservation and diagenesis throughout the samples. We placed each sample in one of three categories based on the degree of diagenetic fabrics present. The observed fabrics suggest some recrystallization from secondary fluids, likely groundwater. We also found paleoenvironmental proxies in the carbonate nodule samples that suggest that at least one sample formed in a shallow lacustrine environment, rather than in a paleosol. Overall, the addition of CL images to previous stable and clumped isotope analyses helps us to determine the diverse range of fluids (both original and secondary) that affected Meade Basin paleosol carbonates. These findings help us better interpret paleoenvironmental conditions in the region.


Presentation