Multi-Proxy Records of Climate and Carbon Cycle Perturbations in the Paleozoic: Integrating Isotope Geochemistry and Sedimentology

Abstract

Carbonate rocks are a valuable archive of past environmental conditions. To glean robust information from this archive, we must understand how carbonate sediments form, ensure our analytical techniques are optimized, and consider how inherently local deposition of sediments can communicate information about global changes in climate. Chapter 1 proposes a new conceptual model for the formation of ooids that suggests that these small carbonate grains could form while buried in the shallow sediment pile during certain intervals of Earth history. Chapters 2 and 3 calibrate the clumped isotope paleothermometer for calcite, dolomite, and apatite, resolving significant discrepancies in calculated paleotemperatures. Chapter 4 applies clumped isotope thermometry to Early Mississippian strata and demonstrates a ~5ºC global cooling and substantial ice volume expansion coincident with a major perturbation to the global carbon cycle. Chapter 5 examines the extent to which diagenesis and facies- and phase-specific effects drive a major Early Mississippian carbon isotope excursion. In aggregate, this thesis outlines a roadmap for assessing changes to climate and the carbon cycle for carbonate rocks in the Paleozoic.