The Effects of Weathering on Rare Earth Element (REE) Uptake: A Study of Pleistocene and Eocene Fossil Material
Open Access
Author:
Grimm, Brittany L.
Area of Honors:
Geosciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Russell W Graham, Thesis Supervisor Russell W Graham, Thesis Supervisor Dr. Maureen Feineman, Thesis Honors Advisor David Martin Bice, Faculty Reader
Keywords:
Rare earth elements geochemistry bone Pleistocene Megalonyx
Abstract:
Rare earth element (REE) geochemistry has been used as a paleontological tool for several decades to extract information from bone and tooth remains. Previous studies include using REE signatures to determine age, provenance, degree of reworking, and depositional environment. While a few studies have found depth-related variations in REE patterns in bones, there is a lack of research studying weathering-related variations in REE signatures. This study presents a differentially weathered Pleistocene Megalonyx jeffersonii rib and Eocene brontothere and rhinoceros specimens from the Bones Galore site that each have a different degree of weathering. After assigning a weathering stage to each bone or section, the bones were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The Pleistocene rib shows increasing weathering from its proximal to distal end, and a corresponding increase in REE concentrations is observed. The most weathered section of the rib on the medial side is five times more enriched in REEs than the least weathered section. The Bones Galore specimens are expected to show a similar trend of increasing REE concentrations with greater weathering rates once the data is made available. This study has significant implications for the use of REE signatures in paleontology, as all studies must now look closely at the weathering present in the bones before relying on REE analysis.
