Date of Graduation
Master of Science in Geology (MS)
Second Committee Member
clumped isotopes, weathering indices, Moenave Formation, carbon cycle, climatic record, CO2 increase
The Triassic is a period of abrupt climate change bracketed by mass extinctions including one driven by the eruption of the Central Atlantic Magmatic Province (CAMP) in the Late Triassic. The Moenave Formation (MF) of Utah and Arizona is ideal to investigate effects of the CAMP on continental strata distal to the eruptive center. This study focuses on the C-isotopic composition of bulk carbonate C from two localities, Blacks Canyon, Zion National Park, UT and Olsen Canyon within Warner Valley, UT. The data collected was used to document a chemostratigraphic record to compare to globally established records and bulk organic C records from the formation. This study also documents paleoclimatic proxies including clumped isotope-derived temperatures, weathering index-derived mean annual precipitation, and atmospheric pCO2 values. When combined with recent detrital zircon geochronologic studies, we record significant climatic changes that can be attributed to the CAMP. Although bulk organic C-isotopes record CIEs similar to those documented in other C-isotope records, the carbonate C-isotope record is more obscure, with minor C-isotope excursions within the Olsen Canyon record. Organic C-isotope results were paired with some clumped isotope analysis to identify changes in temperature during these organic C-isotope excursions. Clumped isotope samples were collected from both sections and sampled for calcite cements. Resulting temperatures ranged from 40ºC to 55 ºC in Olsen Canyon. In Blacks Canyon the temperatures ranged from 35 ºC to 55 ºC. Weathering indices such as CIA-K and CALMAG were used in this study to calculate mean annual precipitation (MAP). The MAP ranged from 220 to 300 mm/yr. Major elemental concentrations were also used to calculate mean annual temperatures (MAT) salinization temperatures which ranged from 20 to 25 ºC and clayeyness temperatures which ranged from 15 to 20 ºC. pCO2 during the CAMP was calculated using measured parameters and estimated S(z) values. pCO2 increases 2-2.5x post excursion and followed by a downward trend afterwards following previous studies in different basins.
Mmasa, D. (2021). Effects of the Triassic-Jurassic Central Atlantic Magmatic Event Recorded in Continental Strata in Western Pangea: The δ13C Record of Warner Valley & Zion National Park. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/4092