Terrestrial carbonates, like those that form in palustrine (wetland) and lacustrine (lake) settings, are important archives of climate and tectonics in the geologic past. However, they often preserve both primary depositional heterogeneity and secondary alteration. Stable isotope geochemistry and terrestrial sedimentology can be used to parse apart the effects of climate fluctuations and tectonic deformation recorded by these archives. For example, the Sevier Orogeny generated significant tectonic deformation in the western USA during the Cretaceous. It is unknown, however, when this region developed high surface elevations and how it responded to a global hothouse climate. I combine sedimentology and stable isotope geochemistry data from the mid-Cretaceous Newark Canyon Formation (NCF), Nevada to add to our understanding of paleoclimate during the Cretaceous and the timing and extent of surface uplift in the western USA (Figure 1-1).
In Chapter 1, I explore the sedimentological evolution of the NCF and find that changes in the sedimentary style were principally driven by regional tectonic deformation caused by the on-going Sevier Orogeny rather than global climate changes (Fetrow et al., 2020). In Chapter 2, I generated δ13C, δ18O, Δ47, and Δ48 records to constrain the paleoclimate conditions of the mid-latitude western USA. As well, I explore the effects of diagenesis from hydrothermal fluids and possible dual clumped isotope (Δ48 vs Δ47) disequilibrium to evaluate which carbonate facies are representative of overall environmental conditions. The lower (~113–112 Ma) and the upper NCF type section (~112–103 Ma) preserve average warm season water temperatures of 41.3°C (± 3.6°C, 2s.e.) and 37.7°C (± 2.5°C, 2s.e), respectively. In Chapter 3, I use a subset of NCF geochemical data to estimate the paleoelevation of the NCF depositional basin. I compare ∆47 temperature and δ18Owater estimates from the NCF (~114 to 112 Ma) to those from the coeval, low elevation Cedar Mountain Formation (~118 to 117 Ma). Similar ∆47 temperatures and δ18Owater values between the two formations indicate that the Sevier hinterland had not experienced uplift by the mid-Cretaceous. These findings provide a critical boundary condition to the Sevier hinterland surface uplift history by confining uplift to the Late Cretaceous.</p
