Open Access. Powered by Scholars. Published by Universities.®

Geochemistry Commons

Open Access. Powered by Scholars. Published by Universities.®

1,217 Full-Text Articles 2,437 Authors 255,399 Downloads 100 Institutions

All Articles in Geochemistry

Faceted Search

1,217 full-text articles. Page 1 of 44.

Chemical Weathering Of Deposits From The 1980 Mount St. Helens Eruption And Its Effect On Stream Water Chemistry, Darlene Gilroy, Dr. Carmen Nezat 2020 Eastern Washington University

Chemical Weathering Of Deposits From The 1980 Mount St. Helens Eruption And Its Effect On Stream Water Chemistry, Darlene Gilroy, Dr. Carmen Nezat

2020 Symposium Posters

Chemical weathering is an ongoing natural phenomenon that aids in the breakdown of solid rocks and contributes to the chemistry of natural waters and soils. Therefore, studying chemical weathering in a given area may provide a better understanding of the natural influencers on nearby water chemistry. The eruption of Mount St. Helens (MSH) in 1980 provides a unique opportunity to study the chemical weathering of young rocks which typically weather more rapidly than older rocks.

The aim of the study was to determine the relative resistance of the volcanic rocks from the 1980 MSH eruption to chemical weathering by using ...


Analysis Of Cryptotephra At Whitney Mesa Nature Preserve, Henderson, Nevada, Alex Newsom 2020 University of Nevada, Las Vegas

Analysis Of Cryptotephra At Whitney Mesa Nature Preserve, Henderson, Nevada, Alex Newsom

Calvert Undergraduate Research Awards

Advanced Undergraduate Winner

Cryptotephra (small volcanic shards ranging 20-80 microns in size) were discovered within Unit X of the Las Vegas Formation at Whitney Mesa Nature Preserve, Henderson, Nevada. Cryptotephra are deposited soon after a volcanic eruption and can be used as a dating tool to create narrow time constraints for surrounding sediments. Cryptotephra have many applications but are mainly useful as a dating tool. Their study has important implications for the understanding of the timing of palaeoclimatological and paleoenvironmental events as well as for archaeological studies to date important events in human history.

The Whitney Mesa cryptotephra were correlated ...


Seeing Through The Ottawan Overprint, Adirondack Mtns., Ny: Integrating Microstructural Analysis, Geothermobarometry, And In-Situ Monazite Petrochronology, Justin Mistikawy 2020 University of Massachusetts Amherst

Seeing Through The Ottawan Overprint, Adirondack Mtns., Ny: Integrating Microstructural Analysis, Geothermobarometry, And In-Situ Monazite Petrochronology, Justin Mistikawy

Masters Theses

Integrating field observation with petrochronology is critical for understanding the tectonometamorphic evolution of the North American Grenville Province. Despite methodological advances in geothermobarometry and geochronology, incorporating these data into larger models of the Adirondack Mountains remains particularly challenging due to the presence of multiple generations of deformation, primarily related to the ca. 1190 – 1140 Ma Shawinigan and ca. 1090 – 1020 Ma Ottawan Orogenies (McLelland et al.,2013). The Rock and Bear Ponds area is a dome of tight-to-isoclinally folded metapelites in structural contact with orthogneiss. Fold generations are orthogonal and partitioned such that the northern area is dominated by an ...


Geochemical Analyses Of Base Metals In Sediments And Stream Water Black Cypress Bayou, Marion County, Texas, Melanie L. Ertons 2020 Stephen F Austin State University

Geochemical Analyses Of Base Metals In Sediments And Stream Water Black Cypress Bayou, Marion County, Texas, Melanie L. Ertons

Undergraduate Research Conference

Black Cypress Bayou is a primary tributary of Caddo Lake watershed in eastern Texas. The watershed is underlain by Eocene-aged strata from the Wilcox and Claiborne groups, which represent transgressive/regressive shoreline fluctuations that deposited interbedded friable sandstones and mudstones. The Wilcox Group is of special interest because it contains lignite coal, which has a direct link to heavy metals in sediment and natural waters. Caddo Lake has been listed on the Texas Commission on Environmental Quality 303(d) list for impairment due to mercury in edible tissue since 1995 and Black Cypress Bayou has been listed for impaired waters ...


Geochemical Tracers Of Arctic Ocean Processes: A Study Of Gallium, Barium, And Vanadium, Laura M. Whitmore 2020 University of Southern Mississippi

Geochemical Tracers Of Arctic Ocean Processes: A Study Of Gallium, Barium, And Vanadium, Laura M. Whitmore

Dissertations

The Arctic Ocean is linked to the global oceans and climate through its connectivity with the North Atlantic Ocean and the regional thermohaline deep water formation sites. It’s also a region undergoing rapid environmental change. To inform the community of potential changes in geochemical and biogeochemical cycles, this dissertation addresses three dissolved geochemical tracers (gallium, barium, and vanadium) as indicators of Arctic Ocean processes. Gallium is tested as a replacement for nutrient-type tracers in an effort to deconvolve Pacific and Atlantic derived waters in the Arctic Ocean basins. These water masses carry different heat and salt content and can ...


Characterization Of Magma Storage And Dynamics At Akutan, Semisopochnoi, And Okmok Volcanoes From Analytical And Numerical Models Of Geodetic, Seismic, And Petrologic Data, Kimberly DeGrandpre 2020 Southern Methodist University

Characterization Of Magma Storage And Dynamics At Akutan, Semisopochnoi, And Okmok Volcanoes From Analytical And Numerical Models Of Geodetic, Seismic, And Petrologic Data, Kimberly Degrandpre

Earth Sciences Theses and Dissertations

Volcanic eruptions can cause significant socioeconomic loss, but a better understanding of the processes and dynamics influencing the evolution of volcanic plumbing systems will advance the development of eruption forecasting models that will ultimately mitigate hazards and risks associated with eruptive events. Geologic and geophysical data must be integrated in 3D, finite- element, multiphysical, numerical models to define the coupled evolution of magmatic and crustal stress regimes in volcanic environments, but in data limited regions this is not always an option. The remote nature of the Aleutian Island Arc restricts ground-based monitoring and sampling efforts, and due to sparse temporal ...


Thermal Analysis, Compressibility, And Decomposition Of Synthetic Bastnäsite-(La) To Lanthanum Oxyfluoride, Richard L. Rowland, Barbara Lavina, Kathleen E. Vander Kadeen, Lisa R. Danielson, Pamela C. Burnely 2020 Los Alamos National Laboratory

Thermal Analysis, Compressibility, And Decomposition Of Synthetic Bastnäsite-(La) To Lanthanum Oxyfluoride, Richard L. Rowland, Barbara Lavina, Kathleen E. Vander Kadeen, Lisa R. Danielson, Pamela C. Burnely

Geoscience Faculty Publications

Understanding basic material properties of rare earth element (REE) bearing minerals such as their phase stability and equations of state can assist in understanding how economically viable deposits might form. Bastnäsite is the most commonly mined REE bearing mineral. We synthesized the lanthanum-fluoride end member, bastnäsite-(La) (LaCO3F), and investigated its thermal behavior and decomposition products from 298 K to 1173 K under ambient pressure conditions through thermogravimetric analysis, differential scanning calorimetry, evolved gas analysis, and high temperature powder X-ray diffraction. We also investigated the compressibility of bastnäsite-(La) via single crystal X-ray diffraction in diamond anvil cells at an ...


Rare-Metal Alkaline Granite From The Arabian Shield, Saudi Arabia, Abdullah A. Aseri 2020 The University of Western Ontario

Rare-Metal Alkaline Granite From The Arabian Shield, Saudi Arabia, Abdullah A. Aseri

Electronic Thesis and Dissertation Repository

Mineral deposits of high field strength elements (HFSE) and rare earth elements (REE) are commonly within granites that have experienced strong post-magmatic alterations. There has been a long debate on whether the mineralization is due to magmatic and/or hydrothermal processes. The Arabian Shield hosts several economical rare-metal alkaline granites that are poorly understood. This work aims to evaluate the nature of the mineralization in three rare-metal granites from the Arabian Shield, showing distinct mineralization styles ranging between disseminated mineralization at Al-Ghurayyah, pegmatite and hematized granite at Jabal Sayid, and quartz veins at Dyaheen.

The granites from all three areas ...


Active Growth Of Non-Hydrothermal Subaqueous And Subaerial Barite (Baso4) Speleothems In Lechuguilla Cave (New Mexico, Usa), Max Wisshak, Hazel A. Barton, Katey E. Bender, Harvey R. DuChene 2020 Senckenberg am Meer, Marine Research Department

Active Growth Of Non-Hydrothermal Subaqueous And Subaerial Barite (Baso4) Speleothems In Lechuguilla Cave (New Mexico, Usa), Max Wisshak, Hazel A. Barton, Katey E. Bender, Harvey R. Duchene

International Journal of Speleology

Barite (BaSO4) speleothems have been reported from caves around the globe and interpreted to have chiefly formed in phreatic, hypogene, hydrothermal settings. Here we report two contrasting types of barite speleothems (bluish tabular crystals in a shallow pool and actively dripping greenish stalactites), which today form at lower temperatures in the non-hydrothermal and vadose environment of Lechuguilla Cave, New Mexico, USA. Scanning electron microscopy analysis, along with energy- and wavelength-dispersive X-ray spectroscopy (EDS, WDS), as well as X-ray diffraction (XRD), characterize the habit and chemical composition as barite. Fractionation of the minor element calcium is related to growth along ...


Abiotic Formation Of Dissolved Organic Sulfur In Anoxic Sediments Of Santa Barbara Basin, Hussain A. Abdulla, David J. Burdige, Tomoko Komada 2020 Old Dominion University

Abiotic Formation Of Dissolved Organic Sulfur In Anoxic Sediments Of Santa Barbara Basin, Hussain A. Abdulla, David J. Burdige, Tomoko Komada

OEAS Faculty Publications

Sulfurization has been found to enhance organic matter preservation and petroleum formation in marine sediments. However, we do not yet have a comprehensive understanding of sulfurization mechanisms. In this study, we investigated several possible mechanisms of dissolved organic sulfur (DOS) formation in the top 4.5 m of anoxic sediments of Santa Barbara Basin (SBB), California Borderland. Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS), we identified chemical formulas of potential dissolved organic matter (DOM) precursors to these DOS compounds. We also examined how the formulas of abiotically formed DOS changed as a function of depth across a major ...


Crystalline Architecture And Stratigraphy Of Coral Skeletal Density Banding: A Geobiological Record Of Changing Coral Reef Ecology, Kyle Fouke 2020 Bucknell University

Crystalline Architecture And Stratigraphy Of Coral Skeletal Density Banding: A Geobiological Record Of Changing Coral Reef Ecology, Kyle Fouke

Honors Theses

Coral skeletal density banding (CSDB), composed of alternating high density band (HDB) and low density band (LDB) layers that comprise the CaCO3 (aragonite) skeleton of scleractinian corals, are used as chronometers for global paleoclimatic reconstructions of sea surface temperature (SST). Scleractinian coral skeletons have been intensively studied for centuries with detail analysis of the macro- and microscale skeletal structure to establish taxonomic and evolutionary relationships of coral species, mechanisms of biomineralization, and seafloor physical, chemical and biological alteration (diagenesis) of the skeleton. This study is the first to determine the crystalline architecture of HDBs and CSDB stratigraphic sequences in ...


The Dynamics And Speciation Of Arsenic In Drinking Water Wells In Eastern Wisconsin, Evvan Plank 2019 University of Wisconsin-Milwaukee

The Dynamics And Speciation Of Arsenic In Drinking Water Wells In Eastern Wisconsin, Evvan Plank

Theses and Dissertations

Arsenic typically develops in Eastern Wisconsin groundwater as a result of oxidation of sulfide bearing minerals in the limestone bedrock (Schreiber et al. 2000). Naturally occurring arsenic exists in groundwater as oxyanions which have two oxidation states, As(III) and As(V). Under ambient pH conditions As(V) is primarily present as an anion (i.e., H2AsO4-) while As(III) tends to be uncharged (i.e., H3AsO3), making it much more difficult to remove through the existing treatment techniques such as adsorption and reverse osmosis (RO). Although many studies exist establishing arsenic concentrations across Wisconsin, there is a lack of ...


Groundwater Investigations To Support Irrigated Agriculture At La Grange, Western Australia: 2013–18 Results, Robert J. Paul, Gregory Paul Raper, Richard J. George Dr, Nicholas J. Wright, Adam M. Lillicrap, Peter S. Gardiner 2019 Department of Agriculture and Food, Western Australia

Groundwater Investigations To Support Irrigated Agriculture At La Grange, Western Australia: 2013–18 Results, Robert J. Paul, Gregory Paul Raper, Richard J. George Dr, Nicholas J. Wright, Adam M. Lillicrap, Peter S. Gardiner

Resource management technical reports

The Broome Sandstone aquifer is the main aquifer and groundwater resource in the La Grange area, near Broome in the West Kimberley, Western Australia. Land use is dominated by cattle grazing on pastoral stations, dispersed mining and tourism. Irrigated agriculture has developed at a small scale, with about 470 hectares under cultivation in 2014. Groundwater abstraction is licensed under the La Grange groundwater allocation plan (Department of Water 2010) and managed by the Department of Water and Environmental Regulation. The La Grange groundwater allocation area is split into the La Grange North subarea and La Grange South subarea, with groundwater ...


A Granger Causality Analysis Of Groundwater Patterns Over A Half-Century, Nitin K. Singh, David M. Borrok 2019 Missouri University of Science and Technology

A Granger Causality Analysis Of Groundwater Patterns Over A Half-Century, Nitin K. Singh, David M. Borrok

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Groundwater depletion in many areas of the world has been broadly attributed to irrigation. However, more formal, data-driven, causal mechanisms of long-term groundwater patterns have not been assessed. Here, we conducted the first Granger causality analysis to identify the "causes" of groundwater patterns using the rice-producing parishes of Louisiana, USA, as an example. Trend analysis showed a decline of up to 6 m in groundwater level over 51 years. We found that no single cause explained groundwater patterns for all parishes. Causal linkages were noted between groundwater and area harvested, number of irrigation wells, summer precipitation totals, and drought. Bi-directional ...


Evidence Of Variable Climate And Resources During The Late Pleistocene And Holocene At Gona, Ethiopia, Marie White 2019 Murray State University

Evidence Of Variable Climate And Resources During The Late Pleistocene And Holocene At Gona, Ethiopia, Marie White

Steeplechase: An ORCA Student Journal

The African Humid Period (AHP) spanned a period of approximately 15 to 5 thousand years ago (ka) and resulted in Northern and Eastern Africa being wetter than today. This climate change event impacted flora, fauna, and humans to an unknown extent. Much of the work on the AHP across Eastern Africa utilizes lacustrine and marine proxies rather than river-based (fluvial). Gona, located in the Afar region of Ethiopia, is known for its extensive archaeological and fossil records in fluvial deposits. However, the paleoenvironment of the AHP at Gona has not been investigated. This study uses stratigraphy, geochronology, and paleopedology to ...


Chemostratigraphic Correlations Across The First Major Trilobite Extinction And Faunal Turnovers Between Laurentia And South China, Jih-Pai Lin, Frederick A. Sunberg, Ganqing Jiang, Isabel P. Montanez, Thomas Wotte 2019 National Taiwan University

Chemostratigraphic Correlations Across The First Major Trilobite Extinction And Faunal Turnovers Between Laurentia And South China, Jih-Pai Lin, Frederick A. Sunberg, Ganqing Jiang, Isabel P. Montanez, Thomas Wotte

Geoscience Faculty Publications

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower–middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2–Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of ...


Petrogenesis Of Basaltic Lavas In Iceland And The Springerville Volcanic Field, U.S.A.: The Influence Of Tectonic Setting, Depth Of Melting And Volatiles, Marissa Mnich 2019 University of Massachusetts Amherst

Petrogenesis Of Basaltic Lavas In Iceland And The Springerville Volcanic Field, U.S.A.: The Influence Of Tectonic Setting, Depth Of Melting And Volatiles, Marissa Mnich

Doctoral Dissertations

Icelandic basalts were long thought to be low in water (e.g. Gunnarsson et al., 1998), but more recent studies suggest that hotspots, like the Iceland mantle plume, may be a source of hydrous basaltic melts (Nichols et al., 2002). To explore a possible link between location, volatile concentration and resulting petrogenetic implications, samples were collected from eleven volcanic centers throughout Iceland. Water concentrations were measured in melt inclusions and phenocrysts using Fourier transform infrared (FTIR) spectroscopy. Results for a subset of samples indicate variable water in melt inclusions ranging from approximately 50 ppm to over 3000 ppm. Samples from ...


The Potential Of Radium-224 As A Tracer Of Timescales Of Gulf Of Mexico Crude Oil Exposure To The Marine Environment, Matthew T. Kurpiel 2019 Coastal Carolina University

The Potential Of Radium-224 As A Tracer Of Timescales Of Gulf Of Mexico Crude Oil Exposure To The Marine Environment, Matthew T. Kurpiel

Electronic Theses and Dissertations

Petroleum pollution in the marine environment can be deleterious to coastal and marine ecosystems and can have sustained effects for years. While oil slicks on the surface of the ocean are tracked with relative ease using satellite-based technology, deep sea, neutrally-buoyant hydrocarbon plumes remain exceedingly difficult to track. We provide evidence for the utility of Ra-224 as a potential hydrocarbon tracer to determine the marine exposure time of crude oil. We employed time course incubations to constrain a time dependent Ra-224 release signature and tested a variety of timescales, temporal resolutions, oil sources, seawater, and experimental treatments to determine potential ...


#22 - A Calorimetric Study Of The Adsorption Of Oxalate On Hematite Nanoparticle, Natasha Clarke 2019 Georgia State University

#22 - A Calorimetric Study Of The Adsorption Of Oxalate On Hematite Nanoparticle, Natasha Clarke

Georgia Undergraduate Research Conference (GURC)

Many chemical and biological reactions in soils are impacted by the presence of natural organic matter (NOM) that often enhances the bioavailability of nutrient and overall soil fertility. In soils, NOM is strongly correlated with the Al and Fe-oxides content of soils. Therefore, it is important to study the surface interactions of organic molecules with Fe-oxides, particularly at various pH conditions that might control whether organic acids are retained in solid or released to nearby aquatic systems. To that end, this research aims to study the interaction of oxalate, a low molecular weight organic acid with hematite nanoparticles that are ...


Boron Variation And The Subducted Sediment Component In The Volcanics From The Bifurcated Portion Of The Lesser Antilles Island Arc (Laia), Ami Margret Ngo Ward 2019 University of South Florida

Boron Variation And The Subducted Sediment Component In The Volcanics From The Bifurcated Portion Of The Lesser Antilles Island Arc (Laia), Ami Margret Ngo Ward

Graduate Theses and Dissertations

North of Martinique island the Lesser Antilles volcanic arc bifurcates, creating a double arc. Here volcanic activity has migrated up to 50 km westward with time, resulting in two volcanic lines that are distinct in age. The eastern line, commonly referred to as the old arc, was active from Early Eocene to Mid-Miocene (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al., 1988). The western line, commonly referred to as the recent arc, has been active since the late Pliocene, ~6 Ma ago (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al ...


Digital Commons powered by bepress