Physical Sciences and Mathematics Commons^™

Enhancing Our Understanding Of Ancient Oceans Through The Investigation Of Molybdenum Behavior Under Sulfidic Conditions, Rachel Faye Phillips

Open Access Theses & Dissertations

The most abundant trace metal in the ocean today, molybdenum (Mo), exhibits distinct behavior in oxygenated water, where it remains predominantly dissolved, compared to euxinic (i.e., oxygen-free and sulfidic) water, in which it is sequestered into the sediment. This dissimilar behavior allows us to use Mo concentrations and isotopic compositions in sediment to reconstruct marine oxygenation conditions throughout geologic history. However, Mo sequestration mechanisms under euxinic conditions remain unresolved, which limits the accuracy and precision of reconstructions made using Mo signatures in the rock record. For my doctoral research, I experimentally investigated abiotic and biotic Mo sequestration mechanisms under various …

Chemostratigraphic And Paleoclimatic Studies Of Cloverly Formation, Northern Wyoming, U.S.A, Queen Amarachi Kalu

Graduate Theses and Dissertations

The Early – Late Cretaceous transition in Western North America recorded a period of rapid climatic and tectonic change in Earth’s history. Major climate events associated with large igneous province eruptions caused several instances of ocean anoxic events (OAE) and perturbations to the global carbon (C) – cycle. These perturbations to the global C-cycle are observed in the bulk organic C record of both marine and terrestrial deposits and can be used to correlate units across major depositional basins. Major efforts are being made to generate time-constrained palaeontologic and paleoclimate information from the North American Cordilleran foreland basin and C-isotope …

History Of Ice-Rafting In The Arctic Ocean During Glacial Maxima Through Marine Isotope Stage 6, Shannon M. Cofield

OES Theses and Dissertations

Numerous studies attempted to reconstruct Arctic paleoclimate, specifically ice mass timing and locations, during glacial maxima. While some regions, like the Barents-Svalbard Ice Sheet (BSIS) are well-studied, they may benefit from a high-resolution paleo proxy. Other regions are highly contested, such as the East Siberian Sea or the presence of a central Arctic Ocean ice mass.

This research uses an Fe-grain provenance method to (1) define how the BSIS behaved during Marine Isotope Stage (MIS) 2, 4, and 6, and when it retreated; (2) determine the presence and ages of Shelf Ice Masses (SIMs) in the Beaufort Sea and East …

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits well defined …

Paleotemperature Estimates From Diatom Morphometrics In The Amundsen Sea For Marine Isotope Stage 5, Cesar Lopez

Honors Capstones

Because of ever rising temperatures driven by anthropogenic climate change, much attention has been given to the West Antarctic Ice Sheet (WAIS) by the scientific community. This is due to its sensitivity to global climate change and vulnerability for collapse as evidenced by Pleistocene interglacial events. Paleotemperature estimates from the Amundsen Sea are crucial for understanding how global temperature changes impacted WAIS throughout the Pleistocene. Marine Isotope Stage 5 (MIS 5) is of particular interest as it contains different substages and intervals of fluctuating temperatures. This period also is estimated to have had temperatures equal to, or slightly higher than …

Reconstructing Wildfire Regime During The Warm Paleocene-Eocene Climate Using Molecular Biomarkers From The Chuckanut Formation In Northwest Washington, U.S.A., Alexandra Thompson

WWU Graduate School Collection

Wildfires are expected to increase in frequency and severity as climate changes in the Pacific Northwest of North America. To better understand the effect of warming climate on wildfire regimes, I present the first reconstruction of past wildfire frequency and severity during the Paleocene-Eocene transition in northwest Washington state, U.S.A. The Chuckanut Formation is a late Paleocene to Eocene sedimentary unit with a robust paleobotanical record showing the existence of subtropical forests in northwest Washington during the Paleocene, transitioning to a relatively cooler Eocene, dominated by temperate mixed forests. Geochemical records of environmental change coinciding with Paleocene-Eocene climatic change in …