Earth and Planetary Sciences ETDs
Publication Date
8-30-2011
Abstract
This study focuses on high-frequency, subtidal-carbonate cycles (1-8 m thick) within the Woodhurst Member of the Lower Mississippian Lodgepole Formation of southwest Montana. We combined conodont-oxygen isotopes (δ18Oapatite¬) and carbonate-carbon isotopes (δ13Ccarb) with cyclostratigraphy of Woodhurst cycles to test the hypothesis that the cycles developed in response to glacial eustasy, evaluate the timing and initiation of the Late Paleozoic Ice Age (LPIA), and to better understand the carbon budget in response to cycle formation. δ18Oapatite trends across targeted cycles support the hypothesis of glacial eustatic origins along with cooling surface seawater temperatures. High-resolution δ13Ccarb analysis of whole-rock limestones within eleven cycles reveal invariant or nonsystematic δ13Ccarb trends, but the long term trend confirms a major positive excursion reported in previous studies of coeval deposits, values peak at ~ 7.5 ° in the upper S. isosticha conodont Zone.
Degree Name
Earth and Planetary Sciences
Level of Degree
Masters
Department Name
Department of Earth and Planetary Sciences
First Committee Member (Chair)
Atudorei, Viorel
Second Committee Member
Fawcett, Peter
Language
English
Keywords
Early Mississippian, Conodonts, Lodgepole Formation, Cycles
Document Type
Thesis
Recommended Citation
Wallace, Zachary. "Investigating evidence of high frequency glacial eustacy in the Lower Mississippian (Tournasian) Lodgepole Formation of southwest Montana : insights from conodont oxygen isotopes." (2011). https://digitalrepository.unm.edu/eps_etds/97