Earth Sciences Department Theses and Dissertations

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About the Program

The IUPUI graduate program in Geology leads to a Master of Science degree from Indiana University. Our terminal degree at the IUPUI campus is the Master of Science. As a result, our faculty are able to focus their attention on our Masters program student research. We offer a thesis and non-thesis option; however, typically only thesis-option students are considered for funding. Our thesis option requires 24 credit hours of graduate level courses and 6 credit hours of a research thesis. We have between 8-12 full-time graduate students per year.

Interested students should contact us prior to applying. If applicable, an appointment/visit can be set up for you to see our facilities and meet a few of our faculty. Students can apply with an interest in a specific faculty member or a group of faculty members. Admission decisions are decided by our graduate committee and not individual faculty members. Once you enter the program, you will take a majority of your courses in your first year. Also, you will choose your research advisor and submit your thesis (research) proposal. Your second year (including the summer) is focused on completing your research project and writing your thesis while finishing your course work.

For more information: http://www.geology.iupui.edu/Degree_Programs/Graduate_Studies/index.htm

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Investigating the Effects of Synoptic-Scale Climatic Processes on Local-Scale Hydrology by Combining Multi-Proxy Analyses of Lacustrine Sediments and Instrumental Records
(2022-09) Gibson, Derek Keith; Bird, Broxton; Gilhooly, William, III; Jacinthe, Pierre-André; Licht, Kathy; Wang, Xianzhong
Paleoclimate records from North and South America were used to develop a holistic understanding of global paleo-hydroclimatic drivers across a range of boundary conditions. Here, geophysical analysis of lacustrine sediment stratigraphy at Lago de Tota, Boyaca, Colombia provided evidence for significant lake-level fluctuations through the late Quaternary and produced a record that potentially spans the last 60 ka. Seismic data revealed a series of off-lap and on-lap sequences in the upper ~20 m of sediments that indicated large amplitude changes in lake-level, driven by variability in the mean latitude of the Intertropical Convergence Zone as controlled by insolation- and ocean circulation-driven hemispheric temperature gradients during glacial/stadial and interglacial/interstadial events. In North America, late Holocene flood recurrence in the Midwest and Holocene changes in the mean latitude of the polar front jet stream were investigated through multi-proxy examinations of sediment cores collected from swale lakes in northern Kentucky and southern Indiana, and a glacially formed kettle lake in northern Indiana. These results showed that the midlatitude jet stream was displaced to the south during the late Holocene, which increased the amount of Midwestern precipitation sourced from the northern Pacific and Arctic, especially during prolonged cool conditions. During these cool periods, when atmospheric flow was meridional and a greater amount of precipitation was delivered from the northerly sources, Ohio River flooding increased. During warm conditions, when clockwise mean-state atmospheric circulation advected southerly moisture from the Gulf of Mexico into the Midwest, flooding on the Ohio River decreased. At present, streamflow in the Midwest is demonstrated here to be generally increasing, despite atmospheric conditions typically associated with reduced streamflow in the paleo-record, due in part to increasing precipitation and modern land-use dynamics. Together, these studies demonstrate the sensitivity and vulnerability of local-scale hydrological processes to synoptic climate change.
Quantifying the Responses of Vegetation to Environmental Stresses
(2022-09) Lanning, Matthew L.; Wang, Lixin; Wang, Xianzhong; Novick, Kimberly Ann; Jacinthe, Pierre-André; Gilhooly, William P.
I examined interactions between plants and the environment they live in along the soil-plant-atmospheric continuum and addressed the effects of drought and acid deposition on plant water use. Using a novel stable isotope technique, I showed that plant water source utilization can be modulated in some species based on the soil and atmospheric conditions they experience, whereas others only access a single subsurface water source. By modeling cuticular conductance in multiple plant species, I showed that the variability of cuticular conductance across species is largely related to the changes in leaf water potentials between pre-dawn and midday measurements collected in field studies. I also assessed the individual and combined effects of soil water stress and atmospheric water stress on plant productivity by developing a new methodology, which can be used across scales. In doing so, I found that in deciduous broad-leaf forests, periods of high vapor pressure deficit caused sufficient hydraulic stress to reduce plant productivity more than low soil water content alone, and often reduced productivity to levels equal to periods of both low soil water stress and high vapor pressure deficit. Utilizing historical data from a whole forest acidification experiment, I was able to link the stress of nutrient deficiencies caused by acid deposition (specifically calcium) to increases in plant water utilization. This was the first observation of such an effect at the ecosystem scale and could have significant implications for understanding water availability in the future. Finally, I assessed a common method for extracting cellulose from tree rings for isotope analyses, which is often used to determine the historical water use efficiency of plants. I was able to determine chemical alteration to the cellulose molecule using stable isotope measurements and spectroscopy. The chemical modification seems to be systemic and therefore could be addressed through mathematical corrections to existing data. Having accurate values of plant water use efficiency is extremely important for understanding how different stressors in the past changed the way plants used their water resources. My series of studies provide new insights and tools to evaluate the plant-environment interactions in current and future environments.
Examining Ecosystem Drought Responses Using Remote Sensing and Flux Tower Observations
(2022-09) Jiao, Wenzhe; Wang, Lixin; Novick, Kimberly A.; Filippelli, Gabriel; Wang, Honglang; Li, Lin
Water is fundamental for plant growth, and vegetation response to water availability influences water, carbon, and energy exchanges between land and atmosphere. Vegetation plays the most active role in water and carbon cycle of various ecosystems. Therefore, comprehensive evaluation of drought impact on vegetation productivity will play a critical role for better understanding the global water cycle under future climate conditions. In-situ meteorological measurements and the eddy covariance flux tower network, which provide meteorological data, and estimates of ecosystem productivity and respiration are remarkable tools to assess the impacts of drought on ecosystem carbon and water cycles. In regions with limited in-situ observations, remote sensing can be a very useful tool to monitor ecosystem drought status since it provides continuous observations of relevant variables linked to ecosystem function and the hydrologic cycle. However, the detailed understanding of ecosystem responses to drought is still lacking and it is challenging to quantify the impacts of drought on ecosystem carbon balance and several factors hinder our explicit understanding of the complex drought impacts. This dissertation addressed drought monitoring, ecosystem drought responses, trends of vegetation water constraint based on in-situ metrological observations, flux tower and multi-sensor remote sensing observations. This dissertation first developed a new integrated drought index applicable across diverse climate regions based on in-situ meteorological observations and multi-sensor remote sensing data, and another integrated drought index applicable across diverse climate regions only based on multi-sensor remote sensing data. The dissertation also evaluated the applicability of new satellite dataset (e.g., solar induced fluorescence, SIF) for responding to meteorological drought. Results show that satellite SIF data could have the potential to reflect meteorological drought, but the application should be limited to dry regions. The work in this dissertation also accessed changes in water constraint on global vegetation productivity, and quantified different drought dimensions on ecosystem productivity and respiration. Results indicate that a significant increase in vegetation water constraint over the last 30 years. The results highlighted the need for a more explicit consideration of the influence of water constraints on regional and global vegetation under a warming climate.
A High-Resolution Study of Local Diagenetic Effects on the Geochemistry of the Late Ordovician Kope Formation
(2022-09) Becerra, Evelyn S; Gilhooly, William P., III; Licht, Kathy; Filippelli, Gabriel
The Ordovician (485-444 Ma) was a highly dynamic period, characterized by significant evolutionary and climatic change. Paleozoic fauna which evolved during the Great Ordovician Biodiversification Event (GOBE) populated extensive epicontinental seaways. Major sea level fluctuations during The Hirnantian glaciation are believed to have led to a mass extinction event at the End Ordovician. However, a reassessment of Early Paleozoic fossil assemblages suggests the onset of extinctions began in the mid-Katian, ~3 million years before the Hirnantian. The Kope formation, within the North American succession of the Katian, was deposited during the peak biodiversification of the GOBE at the point which a biological crisis begins. The well-studied series of interbedded shale and fossiliferous limestone beds, deposited within a shallow epeiric sea, provide ideal sedimentological and paleontological context to interpret sediment geochemistry recorded at the onset of a global mass extinction. For a high-resolution section of the Kope, δ34Spyrite show an extraordinary range of variability, up to 64.5‰, with systematic oscillations throughout the core. The isotope signal represents a mix of pyrite formed at the time of deposition and during diagenesis. As sea levels fluctuated, the amount of sediment delivery influenced the connection of sediment porewaters to overlying seawater sulfate and the location of the sulfate reduction zone, which in turn, masked the primary signal. Reactive iron data suggest low oxygen concentrations in the water column, however fossil assemblages found throughout the Kope suggest otherwise. Changes in sedimentation can mask the water column signal, so these data also capture an aggregate signal. δ15Nbulk show an upsection decrease of 4.4‰, followed by a 3.4‰ increase. Though this excursion can be interpreted as a switch to increased denitrification in a low oxygen environment, the fossil record suggests the data capture localized diagenetic reactions that occur below an oxic water column. Perturbations in the ocean-climate system is often based on the interpretation of stable isotope excursions, and although excursions are diagnostic of changes to biogeochemical cycles, they may not fully account for diagenetic reactions that mask primary signals. The results from the Kope demonstrate strong localized, not global, controls on the sediment geochemistry.
New Insights Into Impact Glass Formation and Evolution Using Machine Learning and Aerodynamic Levitation Laser Heating Experiments
(2022-09) Marrs, Ian James; Macris, Catherine; Barth, Andrew; Druschel, Gregory
Impact processes, where a meteor strikes a planetary body’s surface, are ubiquitous in the Solar System. These highly energetic events require study by both computational methods and experimental investigation. An impact process of particular interest to our study is the impact plume, a collection of vaporized rock and superheated gases that is produced during an impact event. Tektites are silica rich (roughly rhyolitic), extremely dry, and often contain both lechatelierite inclusions (amorphous SiO2) and flow textures (schlieren) and are an impact product of particular interest to this study. Tektites likely form either very early in the impact process or within the impact plume itself as condensates, and therefore offer a unique insight into the early stages of the impact cratering process. Here, we present both the results of the statistical analysis of published tektite geochemistry and the geochemical analysis of a variety of glasses produced in an aerodynamic levitation laser furnace. The major findings of the statistical analysis are that the variance of tektite geochemistry is broadly controlled by MgO, CaO, K2O, and Na2O, that the Australasian strewn field (an extensive region of tektite distribution) is best subdivided into five geochemical subgroups, and that random forest classification models can predict the strewn field or geochemical subgroup of an unknown tektite with >94% accuracy. In terms of our heating experiments, in nearly all cases, Na2O and K2O are rapidly lost from the melt due to evaporation, while Al2O3, CaO, and TiO2 become progressively enriched. Volatility is far more dependent on peak heating temperature than on heating time. Additionally, the chemical constituents of basalts are less readily volatilized than those of rhyolites or loess, with few exceptions. We also find that the volatility of the chemical constituents of non-standard samples is far more variable than for standard samples and that oxygen fugacity has a strong influence over elemental volatility in the aerodynamic levitation laser furnace. Changes in oxygen fugacity can either result in variable, exaggerated, or even opposite volatility trends depending on the material and oxide in question.
The Dynamics of the Late Neogene Antarctic Ice Sheets in the Central Ross Sea using a Multianalytical Approach
(2022-06) Mallery, Christopher Wallace; Licht, Kathy J.; Macris, Catherine A.; Gilhooly, William P. III
With the goal of determining ice sheet history in the central Ross Sea since the late Miocene, the provenance of glacial till from IODP expedition 374 site U1522 was assessed using a suite of three analyses. A total of 3,869 zircons, between 250-63 microns in size, from sixteen different cores were measured for U-Pb isotopes via LA-ICP-MS. Zircon data was compared to neodymium isotope and clast lithology datasets from collaborators. Site U1522 shows three distinct provenance shifts from the late Miocene to the Pleistocene, two of which are coincident with Ross Sea Unconformities three and two. Late Miocene samples have abundant Cretaceous zircon populations, radiogenic neodymium values, and clasts interpreted as having a West Antarctic provenance. In latest Miocene samples, zircons are mostly Ross Orogeny age (c. 470 615 Ma) and Cretaceous zircon grains are almost absent, neodymium values are relatively un radiogenic, and dolerite clasts are present signaling a shift to East Antarctic derived ice. Above Ross Sea Unconformity 3, early to mid Pliocene samples show a shift back to West Antarctic provenance with abundant Cretaceous zircons and more radiogenic neodymium values. Late Pliocene to Pleistocene samples, deposited above Ross Sea Unconformity 2, reflect dominant East Antarctic provenance with few Cretaceous zircon dates, relatively un radiogenic neodymium values, and the presence of dolerite clasts. These data are broadly in agreement with ice sheet interpretations suggested by clast analysis from ANDRILL site AND-1B. Permo-Triassic zircon dates suggest the presence of unexposed bedrock of this age beneath the West Antarctic Ice Sheet based on their association with Cretaceous dates that have not been reported from East Antarctica. The zircon dataset also reveals two late Miocene intervals with a previously undocumented Eocene Oligocene magmatic event ~30 40 Ma. The coexistence of Cretaceous dates in these intervals suggests a likely West Antarctic source. The absence of Eocene Oligocene zircons in subsequent Plio Pleistocene sediments may be explained by substantial erosion and offshore deposition of the West Antarctic interior, including volcanic edifices following the Middle Miocene Climatic Transition.
Late Holocene Climate-Flood Relationships on the White River, Indiana, USA
(2022-05) Wright, Maxwell N.; Bird, Broxton; Licht, Kathy; Gilhooly, William, III.
The frequency and magnitude of floods in the midcontinental United States have increased in recent decades due to changing precipitation patterns as global temperatures rise. These trends pose major social and economic risks to the region, which is home to tens of millions of Americans and a global agricultural center. It is therefore critical to understand if current fluvial dynamics are within the scope of past fluvial-climate relationships, or if they represent a novel response to recent climate and land-use changes. Presented is a 1600-year-long flood frequency record for the moderately sized (~29,400 km2 watershed) White River, Indiana. Flood frequencies were determined using 14C-based sediment accumulation rates at Half Moon Pond, an oxbow lake on the lower White River’s floodplain. Comparison with regional paleoclimate data shows that White River flooding was frequent when atmospheric circulation resembled the negative mode of the Pacific-North American (PNA) teleconnection, particularly during the Medieval Climate Anomaly (950-1250 CE) and the Current Warm Period (last ~150 years). During these times, the regional climate was dominated by warm-season precipitation originating from the Gulf of Mexico. Conversely, White River flooding was less frequent during the Little Ice Age (1250-1800 CE) when cold-season precipitation from the North Pacific/Arctic dominated (+PNA-like conditions). The pre-1790 CE White River flood history was antiphased with reconstructed Ohio River flood frequencies from southern Illinois. This dynamic is consistent with discharge in small to moderate sized watersheds being sensitive to rainstorm runoff and large watersheds being sensitive to snowmelt runoff. After 1790 CE, flooding frequencies of both river systems increased to their highest levels, despite a shift to -PNA-like conditions. This change was likely due to extensive Euro-American land-clearance, which increased runoff/erosion by reducing evapotranspiration, interception, and infiltration. While the White River responded strongly to climatic conditions in the past that were similar to present conditions (-PNA-like conditions), recent land-use practices have amplified the effects of the current hydroclimate. Since a warming climate is expected to increase regional average precipitation and extreme rainfall events, and that landscape modifications have lowered surface resilience to hydroclimate events, flooding will likely become more frequent in the coming decades.
Meteoric 10Be as a Tracer for Subglacial Chemical Weathering in East Antarctica
(2021-12) Arnardóttir, Eiríka Ösp; Licht, Kathy; Graly, Joseph; Bird, Broxton; Gilhooly, William
Subglacial chemical processes in Antarctica are potentially significant contributors to global geochemical cycles, but current understanding of their scale and nature is limited. A sequential chemical extraction procedure was developed and tested to investigate the utility of meteoric 10Be as a tracer for chemical weathering processes beneath the East Antarctic Ice Sheet. Subglacial meltwater is widely available under the Antarctic Ice Sheet and chemical constituents within it have the potential to drive geochemical weathering processes in the subglacial environment. Meteoric 10Be is a cosmogenic nuclide with a half-life of 1.39×106 years that is incorporated into glacier ice, therefore its abundance in the subglacial environment in Antarctica is meltwater dependent. It is known to adsorb to fine-grained particles in aqueous solution, precipitate with amorphous oxides, and/or be incorporated into authigenic clay structures during chemical weathering. The presence of 10Be in weathering products derived from beneath the ice therefore indicates chemical weathering processes in the subglacial environment. Freshly emerging subglacial sediments from the Mt. Achernar blue ice moraine were subject to chemical extractions where these weathering phases were isolated and 10Be concentrations therein quantified. Optimization of the phase isolation was developed by examining the effects of each extraction on the sample mineralogy and chemical composition. Experiments on 10Be desorption revealed that pH 3.2-3.5 was optimal for the extraction of adsorbed 10Be. Vigorous disaggregation of the samples before grain size separations and acid extractions is crucial due to the preferential fractionation of the nuclide with clay-sized particles. 10Be concentrations of 2-22×107 atoms g-1 measured in oxides and clay minerals in freshly emerging sediments strongly indicate subglacial chemical weathering in the catchment of the Mt. Achernar moraine. Sediment-meltwater contact in the system was calculated to be on the order of thousands of years, based on total 10Be sample concentrations, local basal melt rates, and 10Be ice concentrations. Strong correlation (R = 0.96) between 10Be and smectite abundance in the sediments indicate authigenic clay formation in the subglacial environment. This study shows that meteoric 10Be is a useful tool to characterize subglacial geochemical weathering processes under the Antarctic Ice Sheet.
Metamorphic P-T Path and Multiple Fluid Events During Burial and Exhumation of the Tso Morari UHP Terrane, NW Himalaya
(2021-11) Pan, Ruiguang; Macris, Catherine A.; Barth, Andrew P.; Gilhooly, William P. III; Moreno, Max Jacobo; Menold, Carrie A.
The Tso Morari terrane within the Himalayan orogenic belt underwent ultrahigh-pressure (UHP) coesite-eclogite metamorphism due to northward subduction of the Indian continent under the Eurasian continent during the early Eocene. In this study we optimized a best protocol for thermodynamically modelling pressure-temperature (P-T) paths of high-grade metabasites using the Tso Morari eclogite as a case study through evaluating the effects of employing commonly used thermodynamic modeling techniques (e.g., programs, thermodynamic datasets, a-X relations). A “fishhook” shaped clockwise P-T path was obtained with a peak pressure of ~28.5 kbar at ~563 °C, followed by a peak temperature of ~613 °C at ~24.5 kbar. The peak pressures predicted by modelling protocols are consistent with the conventional thermobarometry results and petrographic observations from the Tso Morari eclogites. Secondly, thermodynamic modelling using P-M(H2O) pseudosections on Tso Morari UHP rocks indicates three distinct fluid events during the prograde and retrograde metamorphism. Fluid Event 1 caused the fluid-assisted homogenization of prograde garnet cores in eclogite at ~18.5 kbar and ~555 °C; Fluid Event 2 is evidenced by the formation of poikiloblastic epidote (~23.5 kbar and ~610 °C, at the expense of lawsonite) and amphibole (from ~19.0 to ~14.5 kbar at ~610 °C, at the expense of omphacite and talc), and symplectite association (~8.7 kbar and ~625 °C) in the eclogite matrix without external fluid supply. Fluid Event 3 was determined through modelling the amphibolitization of eclogites with external fluid infiltration at ~9.0–12.5 kbar and ~608 °C. This fluid phase most likely derived from the mixing of dehydrated host orthogneiss and/or metasediments during exhumation through the amphibolite-facies zone in the subduction channel. This study demonstrates the need for using careful petrographic observations in parallel with thermodynamic modelling to achieve realistic results.
Evaporating Planetesimals: A Modelling Approach
(2021-10) Hogan, Arielle Ann; Macris, Catherine A.; Barth, Andrew P.; Druschel, Gregory K.
This thesis is a comprehensive investigation into the mechanics of evaporation experienced by planetesimals during accretion, a planet-building process. The evaporation events that these rocky bodies experience govern their chemical evolution, impacting the chemistry of the final body – a planet. Studying these planet-building processes is notoriously difficult (e.g., Sossi et al., 2019). There are still many unknowns surrounding what controls the degree of evaporation these bodies experience, and the resulting chemical signatures. The current study was designed to attempt to define some important parameters that govern silicate melt evaporation. Here, we isolate and evaluate the effects of (1) pressure, (2) oxygen fugacity and (3) the activity coefficient of MgO on evaporating planetesimals through a series of computational models. The model introduced in this study, the ƒO2 Modified KNFCMAS Model, uses a robust stepwise routine for calculating evaporative fluxes from a shrinking sphere. The modelling results are then compared to data from partial evaporation experiments of synthetic chondrite spheres to demonstrate the validity of this model, and to expose unknowns about the physicochemical conditions of high temperature silicate melts experiencing evaporation (in this case, the effective pressure, and the activity coefficient of MgO). Major element-oxide and isotope data from the models yielded two main conclusions concerning planetesimals: (1) the rate of evaporation is controlled by pressure and oxygen fugacity and (2) the chemical composition of the residual melt is controlled by oxygen fugacity and the activity coefficient of MgO. Results from computational modelling and evaporation experiments were used to determine an approximation for the activity coefficient of MgO in a simplified chondritic composition, as well as the effective pressure experienced by the evaporating spheres during the partial evaporation experiments. This study outlines the controls on planetesimal chemistry during evaporation and provides a more accessible means of studying these complex processes.

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