Geochemistry Commons^™

Dolomite Stoichiometry As A Proxy For Fluid Chemistry, Cameron J. Manche

Dissertations

The origin of massive dolomites is a contentious issue in geology. Because modern dolomite is rare, interpretation of ancient dolomites requires the use of proxy resources, most of which provide ambiguous information. High-temperature dolomite synthesis experiments have shown that dolomite stoichiometry, the degree of cation ordering, and reaction rate are controlled by Mg:Ca, temperature, molarity, and salinity of the formative solution. Thus, it is posited here that dolomite stoichiometry may be a useful proxy for fluid chemistry, as are stable isotope and trace element composition of ancient dolomites. High-frequency sample intervals (cm-scale) from the Cretaceous Upper Glen Rose Formation (Comanche …

369— Comparison Of Wilkins Creek And Spring Creek Stream Chemistries, Victoria Taylor, Brooke Stickles

GREAT Day Posters

A stream's chemistry and health can be affected by seasonal fluctuations, environment and land usage. Wilkins Creek and Spring Creek are tributaries of Conesus Lake located in Livonia, New York. The two streams flow through varying terrain. Wilkins Creek flows predominantly through wetlands, residential and agricultural land. Spring Creek runs through the village of Livonia. The different environments may result in altered stream chemistries. An analysis of water chemistry was taken at different points in Wilkins Creek and Spring Creek before they converged. Alkalinity, chloride, oxygen, pH, conductivity, and water temperature were measured at each location. Samples were collected and …

200— Chemical Analysis Of Slag From Standish, Ny, Maria Leonard, Dori Farthing

GREAT Day Posters

From 1883 to 1907, magnetite was smelted in Standish, NY. During this time, a large amount of slag, a byproduct of smelting, was created. The slag is now in a pile that covers ~13 acres in the northeastern region of the Adirondacks. The slag at the site has been classified into 6 broad types based on their physical properties. Exemplars of select types were crushed and analyzed by X-ray fluorescence spectroscopy (XRF). Both major elements and trace element data was collected for these samples. The XRF results indicate that all Standish slag is dominated by SiO2, CaO, and Fe2O3(t) regardless …

Diversity – Independent Factors Predict Elevated Extinction Rates, Dustin Perriguey, Corinne Myers, Jason Moore, Louis Scuderi

Earth and Planetary Sciences ETDs

Multiple linear regression was used to determine the relationships between diversity-independent factors (i.e., abiotic, climatic) 2, 5, and 10 Myrs-prior to the most elevated Phanerozoic extinctions. We constructed five abiotic variables from Phanerozoic proxy records1–5 to compare to extinction rates: mean temperature, temperature instability, carbon cycle instability, continental weathering rates, and habitat instability. All three models were statistically significant (P < 0.05) and explained > 70% of the variation in Alroy’s6 three-timer generic extinction rates. However, the 2 Myr-prior model explained the most variance in extinction rates and had the most predictive power, based on adjusted and predictive R2 (~ 72% and 41%, respectively). Carbon …

Diversity – Independent Factors Predict Elevated Extinction Rates, Dustin Perriguey

Earth and Planetary Sciences Faculty and Staff Publications

Multiple linear regression was used to determine the relationships between diversity-independent factors (i.e., abiotic, climatic) 2, 5, and 10 Myrs-prior to the most elevated Phanerozoic extinctions. We constructed five abiotic variables from Phanerozoic proxy records1–5 to compare to extinction rates: mean temperature, temperature instability, carbon cycle instability, continental weathering rates, and habitat instability. All three models were statistically significant (P < 0.05) and explained > 70% of the variation in Alroy’s6 three-timer generic extinction rates. However, the 2 Myr-prior model explained the most variance in extinction rates and had the most predictive power, based on adjusted and predictive R2 (~ 72% and 41%, respectively). Carbon …

Manganese Oxides In Martian Meteorites Northwest Africa (Nwa) 7034 And 7533, Yang Liu, Woodward W. Fischer, Chi Ma, John R. Beckett, Oliver Tschauner, Yunbin Guan, Usha F. Lingappa, Samuel M. Webb, Vitali B. Prakapenka, Nina L. Lanza, Carl B. Agee

Geoscience Faculty Research

We report the discovery of indigenous Mn-oxides in Martian regolith breccias Northwest Africa (NWA) 7034 and 7533. These Mn-oxides occur in Mn-rich regions as nanocrystals mixed with silicates, FeOOH, and possible phosphates. The Mn-rich regions contain up to 34 wt% Mn and typically display large chemical gradients on the scale of 10–20 μm. The Martian origin of Mn-oxides was established by the presence of Mn-rich glass (4.8–5.6 wt% Mn) in the fusion crust that crosscuts a Mn-oxides-bearing monzonite clast and by the absence of Mn-oxides on the environmentally exposed surfaces (exterior and fractures) of the meteorites. Manganese K-edge X-ray absorption …

Chemical Mapping To Evaluate Post-Depositional Diagenesis Among The Earliest Ceramics In The Teotihuacan Valley, Mexico, Wesley D. Stoner, Barry J. Shaulis

Anthropology Faculty Publications and Presentations

Chemical and mineral sourcing techniques are commonly employed in archaeology to reconstruct patterns of ceramic exchange and raw material procurement practices for the past, but the effects of post-depositional diagenesis are still often ignored despite a number of key studies warning that the composition of ceramics from archaeological deposits often diverges greatly from their original composition at the time of production. This current study on diagenesis derives from a large chemical and petrographic analysis of some of the earliest ceramics (1500-100 cal Before Common Era [BCE]) in the Basin of Mexico at a time when the development of ceramic trade …

Characterization Of Uranium, Lead, And Rare Earth Element Pollution In Natural Soils And Sediments, Hope Rasmussen

Civil and Environmental Engineering Theses and Dissertations

Heavy metals in the environment add to the global burden of pollution, negatively impacting public health and ecosystem resilience. This study included projects regarding uranium (U), lead (Pb), and rare earth elements (REE) in natural samples, due to their known toxicity, ubiquity, and relevance in context to recent pollution trends. The first project focused on testing the potential of using a hydroxyapatite product as a remediation solution for U-contaminated groundwater and soil at an EPA Superfund site. The results showed that the U was sequestered in a highly crystalline mineral form within the solids, guiding the EPA to specify the …

Increasing Analysis Efficiency Through Automation Of Inductively Coupled Plasma Mass Spectrometry (Icp-Ms) Data Reduction Process Using Python, Grace Abigail Martin

Undergraduate Research Symposium Posters

The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) provides elemental analysis through ionization of samples. Numerous geochemistry laboratories utilize the ICP-MS and has become a community standard. The ICP-MS data reduction process is time intensive and involves correction for blank contribution and sensitivity drift during measurement, as well as construction of standard calibration lines based on measurements of standard solutions. We look to decrease turnaround time and increase efficiency through automation of the data reduction process using Python. The ICP-MS data reduction process was 3 hours or more, in our observations. Python packages such as Openpyxl and Pandas, allow us to …

Reconstructing Surface Water Carbonate Ion Concentration Changes In The Eastern Equatorial Pacific Across Glacial Transitions, Lenzie Gail Ward

OES Theses and Dissertations

Today, the eastern equatorial Pacific (EEP) plays a critical role in the global CO₂ budget as a major source of CO₂ to the atmosphere, but recent studies suggest the region may shift to a sink for atmospheric CO₂ under different climate states. Here, I focus on two transitional periods, the last deglaciation (25 kyr to present) and last glaciation (the Marine Isotope Stage (MIS) 5a-4 transition, 96 to 60 kyr), to investigate how the carbon system in the EEP responds to major climate changes. I measured B/Ca ratios in the planktic foraminifera Globigerina bulloides from core MV1014-17JC …

Investigating The Impact Of Meteoric Diagenesis On The Geochemistry Of Carbonate Eolianites, Eleuthera And Water Cay, The Bahamas, Graham S. Bonnot

LSU Master's Theses

The geochemical signatures imparted in major, minor, and trace elements, combined with light isotopes, suggest promising applications regarding the stabilization of meteorically altered limestone eolianites. Previous high-resolution studies have indicated that elements associated with carbonate diagenesis such as Mg and Sr can be valuable proxies for salinity and aragonite dissolution, respectively. In addition to testing these proxies, the analyses of several temperature-, diagenetic-, bioactive-, and redox-sensitive elements were evaluated using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to identify additional indicators during carbonate diagenesis. Two geochemical drivers of U were identified; (1) aragonite dissolution similar to Sr and (2) oxidation …

Application Of Compound-Specific Stable Isotopes And Molecular Biomarkers To Paleoclimatic And Paleoecological Reconstructions, Mingqiu Hou

LSU Doctoral Dissertations

Compound-specific stable isotope analysis and biomarker-based paleothermometry have been increasingly applied to for paleoclimate and paleoecology studies. The first project aims to reconstruct the paleoclimate in the Qaidam Basin during the last glacial period. Qaidam Basin in the Northern Tibetan Plateau is a critical eolian factory located at a unique geographic location that links the Westerlies and the Asian summer monsoons. However, how the interactions of two climatic systems influence the paleohydrology that in turn impacts the eolian production in the Qaidam Basin has been seldom explored. Our compound-specific hydrogen isotope and U^K ₃₇ temperature data found that the …

On The Genesis Of Aluminum-Rich Speleothems In A Granite Cave Of Nw Spain, Jorge Sanjurjo-Sanchez, Carlos Arce Chamorro, Juan Ramón Vidal Romaní, Marcos Vaqueiro-Rodríguez, Victor Barrientos, Joeri Kaal

International Journal of Speleology

Granite massifs often contain caves, with dimensions ranging from a few meters up to 1,000 m, also referred to as pseudokarst. The speleothems in such caves are mostly composed of either Si-rich (commonly opal-A) or Al-rich authigenic mineraloids. Whereas the formation and geochemical composition of opal-A biospeleothems have been studied and are fairly well understood, knowledge on the Al-rich analogues is scarce. This work reports for the first time a study on the composition, accretion process, age and growth rate of an Al-rich speleothem type flowstone from the A Trapa Cave System (Galicia, NW Spain), developed in a granite cave. …

Frozen In Time: A Numerical Modeling Approach To The Study Of Ice Bearing Planetesimals Through Carbonaceous Chondrites, Jasmine M. Bayron

Dissertations, Theses, and Capstone Projects

Icy planetesimals are significant objects of study for meteoritics, planetary science, and astrobiology due to their connections to the origins of life and liquid water on Earth. An existing closed system aqueous alteration model was adapted to simulate several scenarios involving early Solar System geologic processes occurring in an icy planetesimal interior. The model described in this work has been developed not only to test the validity of constraints currently thought to apply to CM1 parent bodies, but to directly compare the implications of these constraints for the isotopic composition and the modal mineralogy of carbonaceous chondrites. Isotopic ratios of …

Coastal Watershed Monitoring And Management: Geomorphology, Geochemistry, And Hydrologic Modeling Of Los Peñasquitos Creek, Ca, Ravleen Khalsa-Basra

Theses

Rivers in semi-arid climates are directly influenced by local geographic and hydrologic conditions and impacted by modifications to hydrology via urbanization. Changes can influence erosion, morphology, habitat sustainability, and watershed health. In highly urbanized southern California coastal regions, these rare open spaces provide vital ecosystem services. Los Peñasquitos Creek in San Diego County is one such watershed. Using stream surveying and laboratory methods we quantified channel characteristics, grain size distribution, total metal concentration [M], organic carbon (%OC), and phosphate to longitudinally characterize the creek for improved management. Results identified three distinct reaches in the watershed (upper, middle, lower). Downstream, depth …

Reassessing Hydrothermal Heat Discharge And The Relationship Of Hot Springs In The North Oregon Cascades, Aaron Alexander Orr

Dissertations and Theses

Reservoir temperatures of hydrothermal systems in the Pacific Northwest reflect the feasibility of geothermal energy production and the tectonic framework of the region. Multicomponent geothermometry techniques were applied to new and historic water chemistry data in the north-central Oregon Western Cascades and the lower Wind River Valley in southern Washington in order to recalculate reservoir temperatures. Revised reservoir temperatures, water chemistry, and isotope data were used to determine relationships between hot springs in the north-central Oregon Cascades. Geothermal reservoir temperatures were estimated for the lower Wind River Valley (98.44 ± 0.96°C) and for Austin and Bagby Hot Springs (100.10 ± …

A Record Of Vapour Pressure Deficit Preserved In Wood And Soil Across Biomes, Adrian Broz, Gregory J. Retallack, Toby M. Maxwell, Lucas C.R. Silva

Biology Faculty Publications and Presentations

The drying power of air, or vapour pressure deficit (VPD), is an important measurement of potential plant stress and productivity. Estimates of VPD values of the past are integral for understanding the link between rising modern atmospheric carbon dioxide (pCO₂) and global water balance. A geological record of VPD is needed for paleoclimate studies of past greenhouse spikes which attempt to constrain future climate, but at present there are few quantitative atmospheric moisture proxies that can be applied to fossil material. Here we show that VPD leaves a permanent record in the slope (S) of least-squares …

Nickel Isotopic Evidence For Late-Stage Accretion Of Mercury-Like Differentiated Planetary Embryos, Shui Jiong Wang, Wenzhong Wang, Jian Ming Zhu, Zhongqing Wu, Jingao Liu, Guilin Han, Fang Zhen Teng, Shichun Huang, Hongjie Wu, Yujian Wang, Guangliang Wu, Weihan Li

Geoscience Faculty Research

© 2021, The Author(s). Earth’s habitability is closely tied to its late-stage accretion, during which impactors delivered the majority of life-essential volatiles. However, the nature of these final building blocks remains poorly constrained. Nickel (Ni) can be a useful tracer in characterizing this accretion as most Ni in the bulk silicate Earth (BSE) comes from the late-stage impactors. Here, we apply Ni stable isotope analysis to a large number of meteorites and terrestrial rocks, and find that the BSE has a lighter Ni isotopic composition compared to chondrites. Using first-principles calculations based on density functional theory, we show that core-mantle …

Atmosphere/Landscape Co2 Interactions In Mammoth Cave National Park: Hydrochemistry Of Cascade River, Great Onyx Cave, Jessica Williams

Mahurin Honors College Capstone Experience/Thesis Projects

High-resolution analysis of water/CO₂/carbonate rock geochemistry was conducted at the Great Onyx Groundwater Basin in Mammoth Cave National Park. The purpose of this work has been to undertake hydrochemical characterization of the karst groundwater in Cascade River, the largest cave stream in the upper level of Great Onyx Cave, which is below a relatively pristine karst landscape.

Hydrochemical monitoring of Cascade River at Biz Falls using field, laboratory, and high-resolution electronic data-sonde measurements has provided a detailed picture of the stream’s behavior with respect to the transport and influence of carbon dioxide in the surface and groundwater system …

Soils And Paleosols, Daniel R. Muhs

United States Geological Survey: Publications

This article reviews the nature of modern and ancient soils. Soils are naturally occurring bodies that mantle most of the land surface of the Earth. They are found on virtually every part of the Earth’s land surface, other than areas covered by water bodies (lakes and rivers), glacial ice, or steep slopes in mountainous terrain. Soils occur at the interface of the geosphere, hydrosphere, biosphere, and atmosphere and are the medium of growth for much of the Earth’s plant and animal life. The study of soils as naturally occurring bodies on the Earth’s surface is called pedology (in contrast to …