Geochemistry Commons^™

Evaluation Of Heavy Metal Pollution, Water Quality, And The Effectiveness Of Remedial Sediment Dredging In The Lower Passaic River, New Jersey, Oluwafemi Soetan

Theses, Dissertations and Culminating Projects

Toxic metal pollution is a leading environmental concern for aquatic systems globally and remedial dredging has been widely employed to mitigate its harmful impacts. In terms of the short-term impacts of remedial dredging, mixed results are reported in several studies. Despite its immediate negative impacts including saturation of water with toxic metals, increased turbidity, and sediment resuspension, positive impacts can be recorded over a stabilization period of 6 – 24 months after dredging. Nevertheless, the sustainability of these recorded positive effects cannot be ascertained as some studies have reported long-term regression in remediated sites’ conditions. Evaluation of success determinants, site-measure …

Investigating Changes In Surface Water Chemistry Across The Llano Uplift And The Balcones Fault Zone In Central Texas Using Strontium And Uranium Isotopes, Hao Tuan Pham

Open Access Theses & Dissertations

The landscape of central Texas is shaped by over one billion years of Earth's history. An array of lithology lies within central Texas along with two large geological structures. The Llano Uplift, characterized by Proterozoic metamorphic and igneous rocks dating back to 1.37 billion years ago, is encircled by Paleozoic and Mesozoic sedimentary rocks. To the southeast of the Llano Uplift lies the Balcones Fault Zone (BFZ), an extensional structural system of mostly normal faults that delineates the transition between Paleozoic-Mesozoic sedimentary rocks and Cenozoic sedimentary cover, which are influential to the regional hydrogeology. This study investigates the hydrogeological dynamics …

Introduction To Nuclear Magnetic Resonance Spectroscopy In A Geochemical Setting, Evan Mack

University Honors College

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool that is heavily employed in organic chemistry, but lacks use in geochemistry. The technique is most useful for characterization and structural analysis of analytes, but also sees use in kinetics analysis, speciation, and detection. This work aims to answer these questions regarding NMR spectroscopy’s use in geochemical settings: Which nuclei are studied? For what purposes is each nucleus studied? What affects the scope of the technique and has caused it to not be widely used? How often is NMR spectroscopy used? What trends are there in the technique’s use? The …

Determining The Climatic Effects Of The Central Atlantic Magmatic Province Across The End Triassic Mass Extinction In The Elliot Formation, Southern Africa, Danielle Elizabeth Oberg

Graduate Theses and Dissertations

Understanding the intricate relation between carbon-cycle perturbations, climate change, and biodiversity stability is crucial in the face of ongoing anthropogenic greenhouse-gas emissions. This thesis explores the impacts of rapid climate change induced by carbon-cycle perturbations and their potential repercussions on global climate. Large igneous provinces, particularly the Central Atlantic Magmatic Province, offer a lens through which to examine the nexus of volcanic activity, mass extinctions, and climate change. The emplacement of Central Atlantic Magmatic Province, covering vast regions across continents, emitted substantial amounts of carbon dioxide, profoundly impacting global climate and ecosystems. The end-Triassic Mass Extinction, attributed to Central Atlantic …

Investigating Controls On Temporal And Spatial Variation Of Dissolved Uranium At Springs In Horn Creek Drainage, Grand Canyon National Park, Arizona, Usa, Collin Davidson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is a critical resource in the Grand Canyon, providing water to local communities, millions of annual visitors, and ecosystems. One major concern for this critical resource is the potential for uranium contamination in conjunction with uranium mining efforts. Upper Horn Bedrock Spring (UHB) in the Horn Creek drainage of the Grand Canyon sits below the oldest uranium mine in the region, Orphan Lode mine. UHB spring contains the highest concentration of dissolved uranium in the region, eclipsing the Maximum Contaminant Level (MCL) set by the USEPA by an order of magnitude on average. This research and recent collaboration with …

Geochemical Analysis Of Basement Rock As A Potential Metal Source In Mississippi Valley-Type Ores, Southern Midcontinent U.S.A., Mackenzie Moorhead

Graduate Theses and Dissertations

Mississippi Valley-Type (MVT) ores are epigenetic, sedimentary hydrothermal base metal deposits that exist worldwide with type localities in the midcontinent United States. These Permian-aged sulfide ores represent an extraordinary concentration of economic metals, Pb and Zn. Ore deposits occur in vast districts that have a rich mining history. The Pb and Zn from these deposits account for 24% of worldwide reserves. The geologic processes responsible for MVT ore genesis are not fully understood, especially the sourcing of ore constituents. In the midcontinent, the Ouachita Orogeny expelled saline hydrothermal brines in response to high rates of subsidence. These fluids migrated through …

Terrestrial Exchange Of Atmospheric Metals: Insights From Fallout Radionuclides, Joshua D. Landis

Dartmouth College Ph.D Dissertations

Forests mediate the exchange of gases and particulate matter (PM2.5 and PM10) between terrestrial ecosystems and the atmosphere over 30% of global land area. Because forest foliage efficiently absorbs PM with persistent pollutants including metals Pb and Hg, as well as CO₂ and gaseous elemental mercury (GEM), this exchange profoundly influences the composition of the atmosphere as well as terrestrial biogeochemical cycles. The processes by which PM is absorbed remain enigmatic, however, due to the complexity of micrometeorological physics and submicron physical scale of the interaction. Here, measurements of fallout radionuclides (FRNs) beryllium-7 and lead-210, which are quintessential tracers …

Evaluating Reclaimed Mines And Heavy Metal Soil Contamination, Torin A. Matthews

ATU Scholars Symposium

Arkansas has a rich history of lead and zinc mining. While there are still some active mines, many historical mines have been abandoned and/or reclaimed. Although most reclamation procedures result in the burial and containment of target minerals, accessory minerals and elements can be leached out of waste materials/tailings piles and include heavy metals (i.e., Pb, As, Cd). We aim to evaluate the soil and watershed of a few abandoned/reclaimed mines in Pope County, AR, for the presence of heavy metals/source minerals. Soil and stream sediment geochemistry will be conducted using a portable x-ray fluorescence analyzer. Field work and sampling …

Investigation Of Temporal Variation In Sediment Deposition Within The Tropical Wouri Estuary Cameroon Using Fourier Transform Infrared Spectroscopy, Olumide Ajulo, Dr. Henry Agbogun, Dr. Hendratta Ali

SACAD: Scholarly Activities

In this study, Fourier Transform Infrared Spectroscopy (FTIR) was employed to qualitatively analyze organic and mineral components of the sediment core collected from the Wouri Estuary. The FTIR spectra revealed distinct transmittance corresponding to different organic and mineral phases, allowing for the characterization of sediment composition. The FTIR spectra showed changes and variation progressively from the bottom to the top. These sediments are proxies for time this can be inferred to say deposition in the Wouri Estuary has always changed.

Qualitative Analysis Of Selected Hydrocarbon Produced In Kansas Using Ftir: An Oil-Oil Correlation Study, Oluwaseun Omoyemi, Henry Agbogun, James Titah

SACAD: Scholarly Activities

Hydrocarbons have been produced in Kansas since the 1860s, however, the properties and characteristics of the produced oil are still poorly understood.

An oil-oil correlation analysis has been conducted on twelve hydrocarbon samples from three subbasins and from five producing intervals within the State of Kansas. Fourier Transform Infrared Radiation (FTIR) was used to characterize the organic functional groups present within the samples and Thin Layer Chromatography (TLC) was used to assess the hydrocarbon fractions in the samples. The FTIR spectrum of all the samples exhibit similar peaks implying similar functionally groups were present in all the samples. The TLC …

Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato

LSU Doctoral Dissertations

The Coos Bay Basin on the southwestern coast of Oregon is a forearc basin that contains exceptionally preserved Eocene to Miocene, tidal to wave-dominated, shallow deltaic to deep marine sediments of the Coaledo Delta. Coastal depositional environments are known to host source, reservoir, and seal rocks. Climate, topographic relief, and geographical position all play an important role in regional vegetation development and oceanic setting. This study assesses 84 outcrop and 12 core samples from Coos Bay for their organic geochemical characteristics and microfossil assemblage to provide source rock characterization information, organofacies descriptions, environmental reconstructions, and age control.

Results indicate the …

Unearthing The Past: A Comprehensive Study Of Natural And Anthropogenic Changes At An Archaeological Site Through Hydrogeologic Connectivity Utilizing Gis, Mehlich Ii Phosphorus Extractant, And Ph, Dana L. F. Herren

Theses

This thesis aims to thoroughly analyze the Mehlich II Phosphorus Extractant and pH levels at the Bains Gap Village Site in Anniston, AL., while examining the impact of various environmental factors and human activities on them. Phosphorus is often used in archaeology as an indicator of human activity. Soil core samples were collected to analyze anomalies in phosphorus levels.

To establish any relationships, phosphorus and pH levels from soil cores were correlated with findings from past excavation units and features. The potential effects of hydrogeologic connectivity on soil phosphorus and pH levels were investigated. Geospatial technologies were used to manage …

Transport Of Multi-Phase Multi-Component Fluids In The Shallow Subsurface Influenced By Soil And Surface Boundary Conditions: Experimental And Numerical Study With Application To Natural Gas Leakage, Navodi Jayarathne

Civil and Environmental Engineering Theses and Dissertations

With the increased use of Natural Gas (NG) as a source of fuel, underground leak-related events are increasingly reported, and some are fatal. Subsurface migration and development up to flammable limits are highly dependent on leak characteristics, soil, atmospheric variables, and other surface and subsurface structural complexities. Although few studies have characterized the transient behavior of leaked NG in the shallow subsurface, the underlying mechanisms and their interactions are not well understood, which prevents prediction of the impact of environmental and operating conditions on gas migration. The study conducted a series of field scale-controlled release experiments and numerical simulations to …

Remote Sensing Techniques To Determine Volcanic Gas Components And Fluxes: Application For Lascar, Chile And Fagradalsfjall, Iceland Volcanos., Felipe S. Rojas Vilches

Earth and Planetary Sciences ETDs

Volcanic plumes allow us to understand different aspects of a volcanic system including magma movements, dynamics, mass transfer, overall gas emissions to the atmosphere, and many processes that impact human life. However, the H₂O gas is poorly constrained due to the intrinsic difficulties of this gas, with high background values and easily dispersed/integrated into the background. In this work we study the gas emissions from Lascar volcano, and Fagradalsfjall volcano, in Chile and Iceland, respectively, using a combination of different ground-based remote sensing techniques and in situ plume measurements, we measure H₂O, SO₂, CO₂, CO, and H₂S from longer and …

Subaqueous Carbonate Speleothems As Paleotemperature Archives – Clumped Isotope Thermometry And Stable Isotope Compositions Of Inclusion-Hosted Water, Attila Demeny, Ágnes Berentés, László Rinyu, Ivett Kovács, Gergely Surányi, Magdolna Virág

International Journal of Speleology

Clumped isotope measurements of carbonates and stable isotope analyses of water trapped in fluid inclusions are both promising techniques to determine carbonate formation temperatures. Cave-hosted carbonate deposits (speleothems) are excellent targets for such studies, but kinetic fractionations and diagenetic influences frequently deteriorate the temperature data obtained from these methods. However, subaqueous carbonate deposits may provide reliable data, as kinetic fractionations are less significant in underwater environments. In this study, subaqueous speleothems, whose formation temperatures were directly measured in the water, were investigated. Additionally, temperatures calculated from the oxygen isotope fractionations between calcite and fluid inclusion-hosted water were compared with clumped …

Correlation Of Geochemical Zones In Great Onyx Cave, Mammoth Cave National Park, To Surficial Geological Units, William Strehl

Mahurin Honors College Capstone Experience/Thesis Projects

Cave passages in Great Onyx Cave, developed within the Girkin and Ste. Genevieve Limestones of Mammoth Cave National Park, contain a variety of secondary features on cave walls, including speleothems such as stalactites, stalagmites, and flowstone, evaporite minerals, and dissolution features such as pits and domes. What secondary features are present on the walls of a cave passage depends on the flow and geochemistry of capillary water that has interacted with the cave passage. In the Mammoth Cave aquifer, five distinct geochemical zones have been broadly defined and each typically contains a particular set of secondary features. Geochemical zonation in …

Nanoscale Studies Of Magnesium Carbonate Precipitation At Ambient Conditions, Ian Shortt

Material Science and Engineering Dissertations - Archive

Currently approximately 8% of global greenhouse gas emissions can be attributed to the construction industry; of these emissions, a little over half of these emissions are due to the production of traditional calcium-based cements. Magnesium carbonate cements present a promising alternative to traditional calcium-based cements, both in terms of emission reductions and in terms of strength. The primary drawback to magnesium carbonate cements is that ambient curing is not yet viable. The objective of this dissertation is to therefore develop greater understanding of the precipitation pathways undertaken by hydrated magnesium carbonates under near-ambient conditions. In the first section of this …

Petrologic And Geochemical Constraints On The Pre-Eruptive Storage Conditions Of Magmas Erupted During The ~12.5 Ka Flare Up Of Medicine Lake Volcano, Ca, Regina M. Khoury

Cal Poly Humboldt theses and projects

The Medicine Lake Volcano (MLV) system in the California Cascades is composed of a large shield volcano with numerous basaltic to rhyolitic vents on and around the flanks, many of which are aligned with N-S trending normal faults. A significant portion of the post-glacial volcanic activity at MLV is comprised of the ~12.5 ka “flare up” eruptions of basalt and basaltic andesite magmas from seven discrete flank vents. Prior work documented surface areas (0.02-198 km²), volumes (0.0001-4.35 km³), and eruption styles (Hawaiian to Strombolian; Donnelly-Nolan, 2010) of the ~12.5 ka deposits. This study uses new geologic …

Global Subterranean Estuaries Modify Groundwater Nutrient Loading To The Ocean, Stephanie J. Wilson, Amy Moody, Tristan Mckenzie, M. Bayani Cardenas, Elco Luijendijk, Audrey H. Sawyer, Alicia Wilson, Holly A. Michael, Bochao Xu, Karen L. Knee, Hyung-Mi Cho, Yishai Weinstein, Adina Paytan, Nils Moosdorf, Chen-Tung Aurthur Chen, Melanie Beck, Cody Lopez, Dorina Murgulet, Guebuem Kim, Mathew A. Charette, Hannelore Waska, J. Severino P. Ibánhez, Gwénaëlle Chaillou, Till Oehler, Shin-Ichi Onodera, Mitsuyo Saito, Valenti Rodellas, Natasha Dimova, Daniel Montiel, Henrietta Dulai, Christina Richardson, Jinzhou Du, Eric Petermann, Xiaogang Chen, Kay L. Davis, Sebastien Lamontagne, Ryo Sugimoto, Guizhi Wang, Hailong Li, Américo I. Torres, Cansu Demir, Emily Bristol, Craig T. Connolly, James W. Mcclelland, Brenno J. Silva, Douglas Tait, Bsk Kumar, R. Viswanadham, Vvss Sarma, Emmanoel Silva-Filho, Alan Shiller, Alanna Lecher, Joseph Tamborski, Henry Bokuniewicz, Carlos Rocha, Anja Reckhardt, Michael Ernst Böttcher, Shan Jiang, Laura M. Hernández-Terrones, Suresh Babu, Beata Szmczycha, Mahmood Sadat-Noori, Felipe Niencheski, Kimberly Null, Craig Tobias, Bongkeun Song, Iris C. Anderson, Isaac R. Santos

OES Faculty Publications

Terrestrial groundwater travels through subterranean estuaries before reaching the sea. Groundwater-derived nutrients drive coastal water quality, primary production, and eutrophication. We determined how dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved organic nitrogen (DON) are transformed within subterranean estuaries and estimated submarine groundwater discharge (SGD) nutrient loads compiling > 10,000 groundwater samples from 216 sites worldwide. Nutrients exhibited complex, nonconservative behavior in subterranean estuaries. Fresh groundwater DIN and DIP are usually produced, and DON is consumed during transport. Median total SGD (saline and fresh) fluxes globally were 5.4, 2.6, and 0.18 Tmol yr⁻¹ for DIN, DON, and DIP, …

Submarine Groundwater Discharge As A Major Nutrient Source In River-Fed Vs. Tidally Dominated Estuaries, Stephanie J. Wilson, Joseph J. Tamborski, Bongkeun Song, Peter Bernhardt, Margaret R. Mulholland

OES Faculty Publications

The tidal tributaries of the lower Chesapeake Bay experience seasonally recurring harmful algal blooms and the significance of submarine groundwater discharge (SGD) as a nutrient vector is largely unknown. Here, we determined seasonal SGD nutrient loads in two tributaries with contrasting hydrodynamic conditions, river-fed (York River) vs. tidally dominated (Lafayette River). Radon surveys were performed in each river to quantify SGD at the embayment-scale during spring and fall 2021. Total SGD was determined from a ²²²Rn mass balance and Monte Carlo simulations. Submarine groundwater discharge rates differed by a factor of two during spring (Lafayette = 11 ± 17 cm …

Geographically Dependent Thermodynamic And Geochemical Evolution In The Post-Batholith Upper Mantle Beneath The Sierra Nevada: Analysis Of The Blue Knob Xenoliths, Eleanor Ruos

Scripps Senior Theses

Xenoliths entrained in recent (Miocene) volcanics from the Sierra Nevada provide insights into a continuously evolving upper mantle during post-batholith generation periods (early Cenozoic–present). Hypothesized mantle refertilization followed by subsequent delamination of the lithospheric root beneath the Sierra provides a contextual framework for analyzing how the upper mantle responds to such events. This study contributes new geochemical data from the ultramafic xenoliths of Blue Knob, including bulk-rock major and trace element data, thin-section petrography, mineral chemistry and thermobarometry, and oxygen isotopes (delta¹⁸O). Blue knob (Eastern Sierra) data are compared to previous works on xenoliths from Chinese Peak and …

Migrating Whooping Crane Activity Near U.S. Air Force Bases And Airfields In Oklahoma, David A. Brandt, Aaron T. Pearse, Mark T. Bidwell, John Conkin, Matthew Butler

United States Geological Survey: Publications

The Aransas-Wood Buffalo population of Grus americana (Linnaeus, 1758; whooping cranes) migrates through the United States Great Plains, encountering places substantially altered by human activity. Using telemetry data from 2017 to 2022, we investigated whooping crane migration behavior around U.S. Air Force bases in Oklahoma. Our study focused on potential collision risks between whooping cranes and aircraft, a substantial concern for aviation safety. We determined that activity was greatest at Kegelman Air Force Auxiliary Airfield, near whooping crane critical habitat. On average, 61 percent of marked whooping cranes used locations west of Kegelman Air Force Auxiliary Airfield and Vance Air …

Water Quality Contaminants Long-Term Spatial Analysis Along The Upper Clark Fork River Superfund Site Between Warm Springs And Garrison, Montana, Raegan Michele Osentowski

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Long-term data of heavy metal contaminants, cadmium, copper, lead, arsenic, and zinc were compiled from the Montana Department of Environmental Quality, DEQ, and the United States Geological Survey, USGS, to investigate the effects of remediation on water quality along the upper Clark Fork River superfund site. Long-term data sets were analyzed at CFR-03A, CFR-27H, CFR-34, and SS-25 along the upper Clark Fork River and Silver Bow Creek. CFR-03A and CFR-27H had full remediation in the immediate vicinity, SS-25 had on-going remediation in the immediate vicinity, and CFR-34 had no remediation in the immediate vicinity. Analysis of heavy metal contaminants is …

Microstructural, Mineralogical, And Chemical Characterization Of The Handys Bend And Flax Creek Meteorites, Kentucky: Relevance For The Iron Meteorite Record, Ethan S.L. Davis

Theses and Dissertations--Earth and Environmental Sciences

Iron meteorites remain the only material view into planetary cores. Despite their scientific relevance, iron meteorites are relatively rare. In June 2021 and March 2022, the Kentucky Geological Survey received requests to identify two metallic specimens discovered in central Kentucky. The specimens were given the provisional names Handys Bend (3175.2 g) and Flax Creek (286.2 g). The goal of this project is to confirm meteoritic origin, characterize their structures and chemistry, assign genetic classifications, and examine potential relations to previous discoveries. Petrography was conducted using scanning electron microscopy. Mineral phases were examined using X-Ray diffraction crystallography. Chemical compositions were determined …

Thermal Alteration Of The Mineralogy Of Calcium Sulfoaluminate Cements: Implications For The Performance Of Rapid Repair Materials, Jillian Cavellier

Theses and Dissertations--Earth and Environmental Sciences

Calcium sulfoaluminate (CSA) was developed in part to lessen the environmental impact of cementitious materials compared to traditional Portland cements. CSA was first put into production in the 1970s and has been undergoing various performance testing to investigate its durability. Yet to be evaluated is CSA’s response to a rapid, high temperature event. In this study, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectrometry and scanning electron microscope imaging were used to analyze alterations in the mineralogy due to such an event. As found in previous studies, after ~125°C, ettringite has been completely dehydrated. Ettringite decomposes into bassanite and calcium …

High Resolution Sedimentary Investigations Of Extant Lakes In North America, John Dilworth

Theses and Dissertations--Earth and Environmental Sciences

Investigation of past lake environments forms the discipline of paleolimnology. Paleolimnological studies seek to evaluate geophysical, geochemical, and ecological proxies and indicators contained within lake sediment archives. Using these potential stores of high-resolution environmental information, questions regarding climate, biological, and geochemical changes experienced by a lake and its watershed can be investigated. This dissertation research utilized lake sediment records from two lakes within North America to study different aspects of environmental change. This dissertation consists of three separate studies presented in three chapters.

Chapter Two presents a retrospective environmental assessment of Jackson Lake, Wyoming to investigate the impacts of dam …

Utilizing Isotope Tracing To Assess Land Use Implications To Tap And Stream Water Chemistry, Katrina Alexis Mcfadden

Theses and Dissertations--Biosystems and Agricultural Engineering

Water quality is an issue that continues to be worsened by extreme flooding, specifically in Eastern Kentucky. The most recent 2022 flooding event in Eastern Kentucky resulted in loss of human life, over $23.3 billion in damaged infrastructure, and impaired human health. Infrastructure failures, such as leaky pipes, are a growing challenge in these regions as rebuilding has occurred. Therefore, the goal of this project was to evaluate water quality in two of the counties most impacted by the 2022 flood in Kentucky, Breathitt and Perry Counties, using sulfur isotopes as a novel tracer to identify potentially failures in distribution …

Water Column Controls On Magnetic Mineral Formation And Preservation, Josephine Benson

Dartmouth College Master’s Theses

Iron-bearing minerals in the sedimentary record are frequently used to reconstruct past depositional environments. This is accomplished through geochemical, magnetic, and mineralogical analyses placed in geological context. These interpretations, however, depend on our understanding of how iron minerals form in nature. To better understand the formation of magnetic iron minerals in redox-stratified depositional settings, the study of modern analogs is crucial to unraveling environmental context no longer available from geological deposits. In this study, I utilized four anoxic and sulfidic stratified lakes within a 100-mile radius to examine the effects of small variations in lake properties on magnetic mineral formation …

An Experiment To Determine Mineral-Associated Organic Matter Turnover In A Sandy Clay Loam, Samantha Abel

All Master's Theses

Soil is an important terrestrial carbon sink. Through regenerative land management, which includes minimizing soil disturbance, the carbon content of soil can be raised towards preindustrial levels. This feat requires effectively storing carbon in a natural system that is inclined to cyclicity. The most stable form of soil organic matter is mineral-associated organic matter (MAOM). This carbon labelling experiment was designed to identify short-term CO₂ fluxes within the soil-plant-atmosphere system, particularly those related to MAOM turnover in the rhizosphere. Basil (Ocimum basilicum) was planted on a plot at the campus farm at Central Washington University. Another plot …

Eruption Initiation Mechanisms And Timescales At A Very-High-Threat Washington Volcano: Clues From Crystal Cargo In Lavas From Mount Baker (Koma Kulshan), Emily Yoder

All Master's Theses

Understanding the timescales of pre-eruptive processes is key for improving forecast models of future eruptions. Mount Baker (Koma Kulshan), WA, is part of the northern Cascade volcanic arc and classified as a very high threat volcano. However, we lack an understanding of the duration of time between the final magmatic process before eruption (potentially the process that initiated the eruption) and the eruption itself. This study focuses on (1) estimating eruption initiation timescales via diffusion chronometry and (2) determining eruption initiation mechanisms for three andesitic lava flows from Mount Baker: Dobbs Creek (~119 ka), Dobbs Cleaver (~105 ka), and Swift …