Geochemistry Commons^™

Hydrogeophysical Assessment Of Groundwater And Saltwater–Freshwater Interface In A Quaternary– Neogene Coastal Aquifer, Kilwa Kisiwani Island, Southeast Tanzania, Simon R. Melchioly

Tanzania Journal of Science

This study aims to identify and explore new potential sites of groundwater resources using geophysical methods, and to demarcate the depth to the saltwater-freshwater interface. Kilwa Kisiwani Island is geologically covered mostly by Neogene and Quaternary alluvial sediments, sand and gravel. The geophysical techniques employed during the research include Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), and Transient Electromagnetics (TEM). The Island has the potential for groundwater occurrences, but the layer with fresh water is shallow and thin. Out of the 18 VES sites, 2 (11%) points have shown non-potential, but the remaining 16 (89%) of the VES sites …

Minerals Rock!: Improving Audience Engagement And Interest In Stem Through Enhancement Of The In-Person And Online Mineral Collection At Ursinus College, Juliette Lyons

Environment and Sustainability Summer Fellows

Museums are a vital source of educational resources for the general public. They provide information on a variety of topics and disciplines and encourage visitors to be excited about and engaged in learning something new. As we work to comprehend key topics such as climate change, it is especially important for the broader public to better understand science, including geology. While the geological collection at Ursinus, Pieces of Earth’s History, is not in a museum, implementing methods that museums use can improve the reception of the collection. Through the application of research gathered through articles, journals, books, and talking with …

Hydrogeochemical Characterization Of Groundwater In Fractured Crystalline Basement Aquifers In Dodoma, Central Tanzania: Implications On Water Quality For Domestic And Irrigation Applications, George J. Ishabairu, Simon R. Melchioly, Charles H. Kasanzu, Gabriel D. Mulibo

Tanzania Journal of Science

Assessment of groundwater hydrogeochemistry characteristics of aquifers plays a vital role in establishing water quality status and its suitability for human and industrial use. The main objective of this research was to carry out hydrogeochemical characterization of groundwater and assess its impacts on water quality and spatial variability of groundwater geochemistry in Dodoma, Tanzania. The methods used include groundwater sampling, laboratory analysis to determine physico- chemical parameters and data processing to classify the groundwater hydrochemical facies. The results show that the average value for pH is 7.2, for electrical conductivity (EC) is 1108 µS/cm and for total dissolved solids (TDS) …

Exploring Paleoproterozoic Marine Redox States In A Young Banded Iron Formation From The Needle Mountains, Jaya Sharma

Earth Sciences Undergraduate Senior Theses

Banded iron formations (BIF) are redox-dependent chemical sedimentary rocks that have served as proxies for marine and atmospheric oxygen and iron conditions throughout Earth's history. While abundant in the Archean and early Proterozoic, the widespread deposition of BIFs declined following the Great Oxidation Event, as oxygenated surface waters prevented the accumulation of ferrous iron. However, the Needle Mountains, located in southwestern Colorado, house an anomalously young BIF deposited between 1786±10 Ma - 1801±6 Ma given existing geochronology. Here, we use rare earth element (REE) systematics, bulk chemistry, and petrographic analysis to determine the depositional conditions under which this BIF was …

Constraining Magmatic Processes In The Central American Arc Using Melt Inclusion Vapor Bubble Analysis And Triple Oxygen Isotope Modeling And Exploration Of Volatile Contributions To The Production Of Continual Radio Frequency (Crf) Lightning Events, John M. Hamilton

Earth and Planetary Sciences ETDs

Magmatic volatiles are key to determining the processes happening in the subsurface that we cannot directly sample. Advances in measuring volatile and isotope contents from erupted volcanic samples have given us the ability to understand magmatic processes, mixing components that produce the bulk magma composition and potentially precursors to eruptive hazards, such as lightning.

Through analysis of melt inclusions that sample the melt at depth and triple oxygen isotope quantification of olivine crystals from multiple volcanic edifices, the three following studies display how I have utilized these analytical techniques to help unravel processes happening in the subsurface that lead volcanic …

Preservation Of Sedimentary Rubidium Isotopic Signatures In Subduction Zones: Insights From The Schistes Lustrés Hp-Uhp Metasediments, Western Alps, Mary Clarich

UNLV Theses, Dissertations, Professional Papers, and Capstones

When oceanic plates bend and sink into the mantle at subduction zones, they carry sediments from the surface down into the mantle. The recycled sediments contain elements, that are depleted in the mantle, thereby influencing the composition of the mantle wedge and the formation of arc magmas, which are the building blocks of juvenile continental crust. However, it remains poorly constrained how much these elements, particularly fluid-mobile elements such as rubidium (Rb), are lost into fluids during metamorphic dehydration, and how much is transported to sub-arc depths where arc magmas are generated. Rubidium in subducting sediments is mainly hosted in …

Elemental And Mineralogical Characterization Of Permo-Carboniferous Coal In The Ngaka Coalfield, Southwest Tanzania: Implications For Coal Quality Variation, John W. Gama, Justina J. Saroni, Remigius L. Gama

Tanzania Journal of Science

Coal from heterolithic seams exhibits distinct chemical characteristics due to interbedded non-coal beds, which influence its quality and usability. Despite extensive research in these settings, the elemental and mineralogical characteristics of the heterolithic sequences of the Mchuchuma Formation (K2) in the Ngaka Coalfield remain poorly documented. This study provides the first detailed assessment of K2 seams across five active mine sites. Eleven representative samples were analyzed using proximate, elemental, and mineralogical techniques, supported by Pearson correlation, binary analysis, and Principal Component Analysis. Proximate analysis revealed that ash content varies across mine sites, with values ranging from 9.17 to 25.03%, volatile …

Effect Of Light Elements On The Melting Behavior Of Liquid Iron Alloys Under Earth’S Inner Core Boundary Conditions, Olaniyi Anisere

LSU Master's Theses

The temperature at Earth’s inner core boundary (ICB) is set by the melting temperature of the iron-rich outer core at core pressures, yet this remains uncertain because melting depends strongly on composition and pressure. Light elements are required to explain the core’s density deficit, but the identity, abundance, and combined influence of these elements on melting under ICB conditions are still debated. This thesis quantifies how candidate light elements modify the melting behavior of iron alloys at ICB-relevant pressures and uses these composition-dependent melting relations to constrain ICB temperature.

Melting relations were determined using molecular dynamics simulations in VASP accelerated …

Response Of Botovskaya Cave To Local And Regional Environmental Dynamics, Jade Margerum, Oksana Gutareva, Franziska Lechleitner, Maria Box, Stuart Umbo, Anton Vaks, Hanno Meyer, Aleksandr Kononov, Aleksander Osintsev, Dimitri Sokol'nikov, Norbert Marwan, Ola Kwiecien, Sebastian Breitenbach

International Journal of Speleology

Speleothems from caves in near-permafrost regions can provide unique insights into the climatic history of temperature-sensitive environments. These regions are often remote and only seasonally accessible, which makes cave monitoring – a requirement for speleothem-based proxy interpretation – challenging. We document ventilation, the infiltration regime, and the isotopic composition of dripwater in Botovskaya Cave in southern Siberia, a host to speleothems previously used to reconstruct Quaternary permafrost dynamics in continental Eurasia. We explore surface and cave temperature records, cave air CO₂ concentration data and stable isotopes in precipitation and dripwater and evaluate infiltration conditions and the sensitivity of speleothems …

Exceptional Variety Of Baryte-Celestine-Series Speleothems In Lechuguilla Cave (New Mexico, Usa), Max Wisshak, Johannes Birkenstock, Andrea Schröder-Ritzrau, Norbert Frank, Hazel A. Barton, Harvey R. Duchene

International Journal of Speleology

An inventory of speleothems primarily composed of the closely related sulfate minerals baryte (BaSO₄) and celestine (SrSO₄) in Lechuguilla Cave (New Mexico, USA) has revealed an extraordinary variety. This includes subaerial stalactites, stalagmites, flowstone, coralloids, wall crusts, floor crystals, snow, frostwork, and subaqueous pool crystals. Large baryte and celestine crystals have also been documented in hydrothermal veins in the host rock, predating the cave and truncated when intersected by it. The respective carbonate mineral phases witherite (BaCO₃) and strontianite (SrCO₃), in contrast, were found to be rare in the studied speleothem samples, …

Exploring Mesoproterozoic Marine Redox States In A Young Banded Iron Formation From The Needle Mountains, Jaya Sharma, Brenhin Keller

Wetterhahn Science Symposium Posters

Banded iron formations (BIF), as redox-dependent chemical sedimentary rocks, have served as proxies for marine and atmospheric oxygen and iron conditions throughout Earth history. While abundant in the Archean and early Proterozoic, the widespread deposition of BIFs declined following the Great Oxidation Event, as oxygenated surface waters prevented the accumulation of ferrous iron. However, the Needle Mountains, located in southwestern Colorado, houses an anomalously young BIFs deposited between 1.786±10 - 1.801±6 Ga given existing geochronology. Here, we use rare earth element (REE) systematics, bulk chemistry, and petrographic analysis to determine the depositional conditions under which this BIF was formed. We …

Timing, Orbital Pacing, And Provenance Of Late Paleogene Loess In The Western United States, Xiangwei Guo

Earth & Environmental Sciences Dissertations - Archive

This project examines the timing of loess emergence, the nature of the fluvial–eolian transition, orbital forcing on dust accumulation, and sediment recycling in the late Paleogene White River Formation (Group) of Wyoming and Nebraska, western United States. By integrating traditional sedimentology with machine learning–enhanced grain-size analysis, this research shows that loess accumulation at Flagstaff Rim in central Wyoming began during active fluvial deposition at approximately 35.8 Ma, indicating a gradual transition from fluvial to eolian conditions. Machine learning complements field sedimentology and granulometric interpretation while enabling the development of new, testable hypotheses. Extending this framework eastward to Toadstool Geologic Park …

The Effects Of A Microplate On Plume-Ridge Interactions: Constraints From Comparing Easter And Juan Fernandez Microplates In The Eastern Pacific Ocean, Katherine Ames, Jennifer Georgen

OES Faculty Publications

This study investigates the nature of plume-ridge interactions near a tectonic microplate using mantle Bouguer anomaly (MBA) gravity calculations. The focus of this investigation is a comparison of the Easter and Juan Fernandez microplates, which are located in the eastern Pacific Ocean along the Pacific, Nazca, and Antarctic plate boundaries. The microplates have several similar characteristics, including general size, time of formation, and clockwise rotation within the larger bounding mid-ocean ridge systems. Unlike the Juan Fernandez microplate, however, the Easter microplate is located near a mantle plume (Easter/Salas y Gomez). Previously published geochemical data suggest that material from this plume …

Supplemental Bibliographic Details. From 2001 Mars Odyssey To Earth’S Climate Crisis: Integrating Gamma Spectroscopy, Martian Soil Simulants, And Plant Genomes For Agroecology, Anchored In Sri Lanka’S Mars-Context Serpentinites, Suniti Karunatillake, Maheshi Dassanayake, Carlos Gary Bicas

Planetary Science Lab

Bibliographic details follow to supplement hyperlinked citations in the multinational GANGOTRI-supporting project conceived by Karunatillake, Dassanayake, and Gary-Bicas

Understanding The Drivers Of Marine Sediment Diagenesis In Carbonate-Bearing Sediments, Alex Reis

Theses and Dissertations--Earth and Environmental Sciences

Marine sediments serve as an important geochemical record used to study how the Earth’s climate and oceans have changed throughout geologic time. As such, it is critical to understand how these sediments can be altered following deposition on the seafloor. This dissertation targeted two key geochemical archives, carbonate and pyrite, to link changing burial conditions with the resulting marine sediment chemistry. In particular, primary carbonate minerals record several indicators of past ocean chemistry, while pyrite preserves information related to the redox state of the sediment during deposition and burial. Additionally, secondary processes associated with changes in pore fluid chemistry and …

Supplementary Material For Experimental Constraints On Rock And Mineral Alteration By Magmatic Gas: Implications For Mars (Safari Et Al., In Review), Natalie Zimmermann

Geosciences Research Data

This file contains supplemental data for the JGR manuscript Experimental Constraints on Rock and Mineral Alteration by Magmatic Gas: Implications for Mars (Safari et al., in review). It includes SEM images and associated EDS spectra of altered targets and phase coatings produced in gas-rock alteration experiments.

Hydrogeochemical And Redox Controls On Nitrate And Arsenic Co-Occurrence In The Western Kansas High Plains Aquifer (Usa): A Composite Health Risk Assessment And The Case For Risk-Informed Private Well Governance, Jonathan Kuffour Owusu

Master's Theses or Doctor of Nursing Practice

Fifty-one private domestic wells across western Kansas were sampled to quantify nitrate and arsenic occurrence, identify geochemical controls, and evaluate carcinogenic and non-carcinogenic health risks for adult and child receptors in a region where groundwater serves as the primary drinking water source with no routine regulatory oversight. Samples were analyzed for major ions, nutrients, and trace elements by ICP-MS, ion chromatography, and UV-Vis spectrophotometry. Shapiro-Wilk testing confirmed non-normal distributions for both contaminants; inter-county comparisons were therefore conducted using Kruskal-Wallis tests with Dunn's post-hoc correction. Health risk was quantified via chronic daily intake (CDI), hazard quotient (HQ), HQ-based Water Quality Index …

Paleoflood Chronology For The West Branch Of The Susquehanna River Using Abandoned Chute Channel Sediments, Pennsylvania, Usa, Juliette A. Vanluven

Honors Theses

Anthropogenic climate change is altering the hydrologic cycle, increasing flood frequency and severity, with associated increased risks in population exposure. This is associated with increasing risks to the population of the Susquehanna River Valley, which supports over 600,000 people today. However, our understanding of the frequencies of large floods is limited by relatively short instrumental records. By studying sediments from an abandoned chute channel in the Robert Allen Natural Area near Williamsport, PA, we can extend the existing flood records using paleoflood slackwater sediments along the West Branch of the Susquehanna River.  Sylvan Dell is an abandoned chute channel that …

Deep Crustal Boundaries As Fluid Conduits: A Geochemical Investigation Of Mvt Mineralization In Kentucky And Beyond, Dairian Boddy M. Boddy

Theses and Dissertations--Earth and Environmental Sciences

Critical minerals are vital to the United States economy and national security, yet their supply chains are at risk. Common minerals in Mississippi Valley-type (MVT) deposits, such as sphalerite, galena, fluorite, and barite, host critical metals such as barium, gallium, germanium, and zinc, which are essential for energy technologies. An investigation of three MVT mineral districts in Kentucky elucidated previously unrecognized systematics, genetic relationships, and sources of ore components using stable and radiogenic isotope geochemistry, particularly from galena, sphalerite, barite, and gangue minerals (e.g., carbonates). The localization and dominant type of mineralization in each district are potentially influenced by deep …

Pre-Eruptive Timescales Via Olivine Diffusion Chronometry For Lava And Tephra Of The Schreibers Meadow Cinder Cone Eruption, Mount Baker (Kulshan), Wa, Sabrina Ansari

All Master's Theses

Mount Baker is a very-high threat Cascade volcano and is located near densely populated areas in northern Washington, putting many at risk if an eruption were to occur. Schreibers Meadow cinder cone is located on the southern flank of Mount Baker and produced the Sulphur Creek (SC) tephra and lava 9.8 ka. Previous work on the SC eruption used petrology and geochemistry to reconstruct the pre-eruptive magmatic architecture beneath Mount Baker Volcanic Field, including olivine-hosted melt inclusions to determine crystallization pressures, as well as plagioclase- and clinopyroxene-derived diffusion timescales to determine magma storage timescales of several months and recharge-to-eruption timescales …

Investigation Of Reey Concentrations In Argillaceous Rocks Associated With Coal Beds In Southwestern West Virginia, Alyssa Cameron Long

Theses, Dissertations and Capstones

Rare earth elements (REEs) and Yttrium are classified as “critical minerals” that are used in many industries and are typically extracted from carbonatites and related alkaline plutonic rocks. The limited availability of REE+Y requires finding alternate sources such as coal fly ash, tonstein, fireclays, and shales. This study investigates the potential enrichment of shales, fireclays, and siltstones interbedded with coal from southwestern WV in REEY, and the mechanisms of such enrichment. Using ICP-AES analysis of various rock types shows that shales, silty shales, and siderite nodules interbedded with Fire Clay and Chilton Coal beds in the Kanawha Formation record the …

Constraining The Tectono-Climatic Evolution Of The Northern Rocky Mountains: Insights From Volcanic Glass, Leaf Water, And Leaf Wax Hydrogen Isotopes, Rijumon Nandy

Earth & Environmental Sciences Dissertations

The Eocene-Oligocene period in the North American Cordillera represents a period of great intrigue with complex interactions among tectonics, climate, and surface processes. Although this period is generally associated with synorogenic extension associated with gravitational collapse of the Cordillera, the paleotopographic history remains debated. Existing studies offer conflicting interpretations, suggesting either sustained elevations or modest uplift during this time. Notably, recent reconstructions based on volcanic glass δD values have proposed renewed uplift during the early Oligocene, which needs to be tested with a more extensive and robust dataset. Concurrently, global cooling and aridification during this interval may have been amplified …

Origin Of The World-Class Eagle, Eagle East, And Tamarack Ni-Cu-Pge Deposits And Comparative Analysis With Other Midcontinent Rift- And Siberian Trap-Related Intrusions, Robert M. Nowak

Dissertations, Master's Theses and Master's Reports

The 1.1 Ga Mesoproterozoic Midcontinent rift hosts the Eagle, Eagle East, and Tamarack Ni-Cu-PGE deposits and Embayment Prospect. These deposits are hosted by ultramafic igneous rocks and have some of the highest Ni-Cu grades on Earth. We use new bulk-rock data and published datasets (bulk-rock, mineral chemistry, and isotopic analyses) to examine major, minor, and trace element trends of both Midcontinent rift-related alkaline and tholeiitic intrusions. In addition, we compare the geochemical data to local kimberlite-hosted lower-crustal xenoliths and local igneous (Archean) and sedimentary (Paleoproterozoic) country rocks. We found the peridotite magma compositions dominantly consist of primitive mantle compositions with …

Non-Destructive Characterization Of Variously Colored Gypsum And Aragonite/Calcite Speleothems From The Cigalère Cave (Ariège, France), Martin Vlieghe, Johan Wouters, Gérald Fanuel, Jean-François Drion Du Chapois, Anne Gallez, Stéphane Pire-Stevenne, Gaëtan Rochez, Johan Yans

International Journal of Speleology

The Cigalère Cave is a 21 km-long karstic cave located in the Ariège Department, in the French Pyrenees, and underlies directly the Bentaillou Pb-Zn-Fe sulfide ores. The cave hosts abundant gypsum mineralizations, some of them exhibiting various colorations including blue, yellow, purple, orange and black. Due to strict preservation policies, these colored mineralizations have not been studied much. Here we propose a non-destructive characterization of five distinct gypsum or carbonate speleothem structures from the Cigalère, exhibiting different colorations. To comply with the preservation policies, no sample was taken from the cave, and all speleothems were analyzed in situ using portable …

Reconstructing Central American Hydroclimate Changes Across Time From Isotopic Signatures In Modern And Paleo-Rainfall Records, Giuseppe Lucia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Tropical monsoon rainfall is a key component of Earth’s climate system and supports the livelihood and economy of billions of people. Yet, projections of future monsoons remain highly uncertain, particularly in regions with distinct physiography and complex land-ocean-atmosphere interactions like Central America, where long and continuous high-resolution paleoclimate data to test climate model simulations are still limited. This series of studies aims to reconstruct monsoon dynamics and underlying forcing controls in Central America on multiple timescales by the analysis and integration of stable isotope data in modern and paleo-rainfall records from Guatemala.

In Chapter 2, I present a daily-resolution, two-year-long …

The Depositional Environment Of The Triassic Cow Branch Formation, Dan River Basin Of Virginia And North Carolina Through Petrographic Study And Geochemical Analysis, And In Relation To Taphonomic Processes And Vertebrate Morphology, Gina M. Workman

All Graduate Reports and Creative Projects, Fall 2023 to Present

The Upper Triassic Cow Branch Formation of the Dan River Basin, located in southern Virginia and northern North Carolina, has long captivated generations of geoscientists. Since the 1970s, researchers have sought to unravel the mystery surrounding the depositional environment of this ancient lake system. This world-class lagerstätte hosts a diverse assemblage of fossil fauna and flora, with a notable preservation bias toward fossil vertebrates, most prominently the archosauromorph, Tanytrachelos ahynis. The geology of the Cow Branch strata continues to evoke a persistent question: Are these sediments representative of a shallow or deep lake?

I undertook a petrographic and geochemical study …

An Investigation Of Paleoclimate Through A Sedimentological Lens In The Gulf Of Mexico And Western North Pacific, Sarah Monica

Dissertations

This dissertation explores the use of sediment cores as proxy data for the reconstruction of paleoclimatic and environmental conditions. Human-caused climate change is leading to dramatic shifts in the global climate. As the instrumental record of climate is relatively short compared to the amount of time Earth has experienced weather, this work aims to extend our knowledge of climate beyond the instrumental record, thereby improving our holistic understanding of the climate system. In Chapter one, sediment cores from the central Texas inner shelf are used to produce a record of intense tropical cyclone (TC) activity over a ~4500-year period. X-Ray …

Pre-Calibration Of Δ18O For Paleoclimatic Interpretations Using Stalagmites In Cueva Ensueño, Puerto Rico, Gabriel Enrique López Borobia, Ny Riavo G. Voarintsoa, Ricardo Sánchez-Murillo, Pablo Antonio Llerandi Román

International Journal of Speleology

Stalagmites are invaluable archivers of past climate conditions, as their oxygen isotopic composition (δ¹⁸O_c) closely mirrors the isotopic signature of the drip water (δ¹⁸O_w) from which they precipitate. This isotopic relationship is governed by the fractionation factor (1000ln¹⁸α), which is temperature dependent. In this research, we studied 1000ln¹⁸α within Cueva Ensueño, a cave situated in Puerto Rico’s northern karst region, as a step toward calibrating δ¹⁸O_c for paleoclimate interpretations using stalagmites. We collected drip waters, measured their temperature in situ, and sampled carbonates from ten selected stations within the cave. Sampling was conducted in December …

Orphan Basalts: Understanding The Origins Of Unassigned Eastern Oregon Basalts, Angela Rae Stetson

Dissertations and Theses

For more than a century, scientists have studied the geologic stratigraphy of eastern Oregon, which chronicles a rich history of volcanic activity spanning millions of years. Recent and ongoing geologic mapping of the northeastern Harney Basin -- along a corridor east of Highway 395 between the towns of Burns and John Day -- provides a more detailed understanding of an area originally mapped only in reconnaissance during the 1960s. At that time, geologic units were poorly delineated, often with entire quadrangles mapped as a single unit. For example, over 90% of the Calamity Butte quadrangle was previously mapped as 'Tba' …

Compound-Specific Isotope Records Of Dust Provenance And Hydroclimate In The North Pacific And Marginal Seas Of East Asia: Integrating N-Alkane Δ13c And Δd With Standardized Analytical Frameworks, Julian W. Traphagan

LSU Doctoral Dissertations

This dissertation presents advancements in compound-specific isotope analysis (CSIA) through methodological innovation and paleoclimate reconstruction in Central and East Asia. Utilizing plant wax n-alkanes from International Ocean Discovery Program (IODP) and Ocean Drilling Program (ODP) sediment cores, this research reconstructs atmospheric circulation shifts responding to tectonic evolution and climate transitions since the Late Miocene.

Chapter 1 investigates hydrogen isotope compositions (δD_wax) from IODP U1430 (Sea of Japan), ODP 886, and ODP 1208 (North Pacific) to trace dust provenance and hydroclimate changes since ~13 Ma. Results reveal persistently segmented source-to-sink systems: the Sea of Japan dominated by westerly …