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Articles 331 - 360 of 1536

Full-Text Articles in Geochemistry

Spatiotemporal Variability Of Soil Water Δ18o And Δ2h Reveals Hydrological Processes In Two Floodplain Soils, Amanda Ceming-Barbato Sep 2021

Spatiotemporal Variability Of Soil Water Δ18o And Δ2h Reveals Hydrological Processes In Two Floodplain Soils, Amanda Ceming-Barbato

LSU Master's Theses

The movement of water through soil is preferential and heterogeneous. Subsurface interactions between mobile flows and the soil matrix are not uniform and are therefore difficult to predict through time and space. The use of stable isotopes of hydrogen (2H) and oxygen (18O) as conservative tracers of water movement is improving understanding of soil hydrological processes, yet field-scale observations of isotopic variability remain scarce despite implications for identifying dominant hydrologic processes. We sampled two adjacent soils at a ridge-swale topography floodplain forest to determine soil water isotopic variability at a 20 cm depth resolution in soils …


Sorption Of Metals At The Barite (001)-Water Interface, Inva Braha Sep 2021

Sorption Of Metals At The Barite (001)-Water Interface, Inva Braha

Student Theses

Abstract

Ion desorption processes control the retention of ions, such as Pb2+, at barite surfaces, whereas ion adsorption processes are a likely initial step in the incorporation of divalent cations, such as Sr2+ and Pb2+, into barite. Based on previous studies on samples dominated by flat terraces with relatively few defects, Sr2+ and Pb2+ adsorb and incorporate at the barite (001)-water interface (Bracco et al., 2019; Bracco et al., 2020). Here, I measured how susceptible lead (Pb) is to desorption and the role surface variability plays in its sorption behavior. First, I measured …


Laboratory Capabilities, University Of North Dakota. Energy And Environmental Research Center Sep 2021

Laboratory Capabilities, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet about the Energy & Environmental Research Center’s laboratory capabilities including reservoir characterization, organic geochemistry, fluid sampling, and material analysis. A list of publications and laboratory information is also included.


Palynology And Paleoclimatology Of The Chicxulub Impact Crater In The Early Paleogene, Vann Smith Aug 2021

Palynology And Paleoclimatology Of The Chicxulub Impact Crater In The Early Paleogene, Vann Smith

LSU Doctoral Dissertations

At the end of the Cretaceous Period, a large bolide impacted the Earth and formed the Chicxulub impact crater in the Yucatán Peninsula, Mexico. In 2016, International Ocean Discovery Program (IODP) Expedition 364 Site M0077 drilled into the buried peak ring of the crater, recovering a marine Paleocene to early Eocene post-impact section deposited on top of the impact breccia. Palynological analysis of 195 samples from the post-impact section has yielded the first pre-Holocene vegetational record from inside the Chicxulub impact crater and the first palynological record of the recovery of life following the end-Cretaceous mass extinction from inside the …


Impacts Of Oil And Gas Wastes On Landfill Leachate, Sewage Treatment Plants, And The Environment, Lauren Badertscher Aug 2021

Impacts Of Oil And Gas Wastes On Landfill Leachate, Sewage Treatment Plants, And The Environment, Lauren Badertscher

Electronic Theses and Dissertations

Between January 2011 and March 2021 oil and gas wells in Pennsylvania produced

305,637,795 barrels of liquid waste and 6,992,957 tons of solid waste with the majority from

Marcellus Shale unconventional wells. This waste is not considered hazardous and over 89% of

the solid waste generated by unconventional and conventional oil and gas extraction has been

disposed of in landfills over the past decade. This study examined trends in the quantity of waste

produced and methods of disposal. Landfills accepting this waste were identified and their

general method of leachate treatment, using onsite facilities or offsite at wastewater treatment

plants, …


Geology Of The Clairmont Springs 7.5-Minute Quadrangle And Geochronology Of The Alabama Blue Ridge, Adelie Ionescu Aug 2021

Geology Of The Clairmont Springs 7.5-Minute Quadrangle And Geochronology Of The Alabama Blue Ridge, Adelie Ionescu

Graduate Theses/Dissertations

The Alabama Blue Ridge (USA) of the southern Appalachians contains metamorphic rocks and structures associated with island arc accretion and continent-continent collision that record the Acadian and Alleghenian orogenies. The western Blue Ridge is underlain by Cambrian to Mississippian, clastic and carbonate, low-grade, greenschist facies metamorphic Talladega belt that formed outboard from the Alabama promontory or along the Laurentian margin. The eastern Blue Ridge contains the Neoproterozoic to Paleozoic, lithologically diverse, high grade, middle to upper amphibolite facies Ashland Supergroup. Geologic mapping of the Clairmont Springs 7.5- minute quadrangle unveils tectonic relationships between the eastern and western Blue Ridge and …


Re-Evaluation Of The First Metamorphic P-T Path Using Quig Barometry And Equilibrium Thermodynamics, Sam Couch Aug 2021

Re-Evaluation Of The First Metamorphic P-T Path Using Quig Barometry And Equilibrium Thermodynamics, Sam Couch

Boise State University Theses and Dissertations

Quartz in garnet (“QuiG”) barometry is a relatively new technique that uses physical properties of minerals to estimate the pressure of garnet nucleation and growth history independent of chemical equilibrium. QuiG barometry was used to determine pressures of garnet growth and compared to thermodynamically calculated P-T conditions for two samples (FH-1M and Z3H) from the Lower Shieferhülle (Formation), Tauern Window, Austria. FH-1M was the first sample for which a P-T path was calculated through inversion of chemical zoning in garnet (Selverstone et al., 1984). Mineral Assemblage Diagrams (MADs) and geothermobarometric techniques were used to determine P-T conditions for garnet nucleation …


Understanding The Chemical Weathering Rate And Element Mobility Of Soils: Using U-Series, Nd-Sr Isotopes Ree And Quantum Chemistry Computational Simulation, Jiye Guo Aug 2021

Understanding The Chemical Weathering Rate And Element Mobility Of Soils: Using U-Series, Nd-Sr Isotopes Ree And Quantum Chemistry Computational Simulation, Jiye Guo

Open Access Theses & Dissertations

Soil played as the central role in the interaction of biosphere, hydrosphere, lithosphere and atmosphere and is the heart of earth's critical zone study. The weathering and element mobility of soils have drawn considerable attention in soil studies since the complexity of these processes and the critical influence towards the earth and humanity, e.g., the global carbon cycles and fertilization. However, the interaction between soils and various factors including precipitation, bedrock ages, altitude is not well understood. Basse-Terre Island at French Guadeloupe, a small volcanic tropical island that has steep environmental gradients of bedrock ages, topography and precipitation, can be …


Develop A Multi-Functional Green Pervious Concrete (Mgpc) Pavement With Polycyclic Aromatic Hydrocarbons (Pahs) Removal Function., Hong Shang Aug 2021

Develop A Multi-Functional Green Pervious Concrete (Mgpc) Pavement With Polycyclic Aromatic Hydrocarbons (Pahs) Removal Function., Hong Shang

Electronic Theses and Dissertations

Stormwater runoff induced Polycyclic Aromatic Hydrocarbons (PAHs) contaminant increasingly imperils the groundwater quality and the sustainable development of human society due to the potential carcinogenic risks. Pavement can be considered as the first line of defense for contaminant removal of the stormwater runoff. New construction materials with stormwater runoff quantity and quality control are in urgent demand for updating the existing pavement system. An innovative material called Multi-functional Green Pervious Concrete (MGPC) was developed in the department of Civil and Environmental Engineering at University of Louisville. This material uses organoclay as the amendment to enhance the PAHs removal capacity of …


Reconstructing 1856-7 California Mining Patterns From Placer Gold Recovered From The Wreck Of The Ss Central America, Kathryn Ruth Vonsydow Aug 2021

Reconstructing 1856-7 California Mining Patterns From Placer Gold Recovered From The Wreck Of The Ss Central America, Kathryn Ruth Vonsydow

Electronic Theses, Projects, and Dissertations

The discovery of the SS Central America 1857 shipwreck site provides a time capsule that can be used to address questions about the spatial and temporal patterns of placer mining in California during the peak of the gold rush. Samples of placer gold in the collections of museums and private individuals can have uncertain pedigree due to labeling issues and alterations by cleaning and curatorial processes. However, placer gold from the 1857 shipwreck could only have come from the Mother Lode Country of California, as no other gold districts had yet been found in western North America. I compared the …


New Perspectives On Prolific And Voluminous Rhyolite Volcanism Of The Mahogany Mountain--Three Fingers Rhyolite Field, Eastern Oregon, Robert Andrew Jackson Jul 2021

New Perspectives On Prolific And Voluminous Rhyolite Volcanism Of The Mahogany Mountain--Three Fingers Rhyolite Field, Eastern Oregon, Robert Andrew Jackson

Dissertations and Theses

Voluminous silicic volcanism of the Mahogany Mountain--Three Fingers rhyolite field (MM--TFrf) is spatially and temporally associated with mid-Miocene flood basalts of the Columbia River Basalt province. Early studies of the area advocated for a two-caldera model consisting of the Mahogany Mountain and the slightly younger Three Fingers caldera with pre- and post-caldera effusive rhyolite eruptions. Although close in time, the calderas were thought to be spatially offset producing the tuff of Leslie Gulch and the tuff of Spring Creek. Finding that the tuff of Spring Creek, that is exposed in Leslie Gulch, is an altered product of the tuff of …


Petrology And Geochemistry Of Evolved Achondrites: Planetesimal Mantles And Crusts, Zoltan Vaci Jul 2021

Petrology And Geochemistry Of Evolved Achondrites: Planetesimal Mantles And Crusts, Zoltan Vaci

Earth and Planetary Sciences ETDs

Melting and differentiation are fundamental to early solar system evolution on planetary bodies that accreted enough material to heat up radioactively or through impacts and breach their solidi. Partially and fully melted material is present in the meteorite record in the form of primitive achondrites and achondrites, which are fragments of planetesimals that underwent heating events in the first few million years of solar system history. Although the vast majority of this material is mafic or ultramafic, new evolved samples, recovered in the last few decades, are pushing the petrologic and geochemical boundaries of planetesimal melting, differentiation, and crust formation. …


Computer Simulations Of Diffusional Isotope Effects And Dynamical Properties Of Silicate Melts, Haiyang Luo Jul 2021

Computer Simulations Of Diffusional Isotope Effects And Dynamical Properties Of Silicate Melts, Haiyang Luo

LSU Doctoral Dissertations

Silicate melts have served as transport agents in the chemical and thermal evolution of Earth. Diffusional isotope effect in silicate melts is the key to interpret isotope variations in lots of geological samples. Isotopic mass dependence of diffusion is commonly expressed as (Di/Dj)=(mj/mi)^β, where Di and Dj are diffusion coefficients of two isotopes whose masses are mi and mj. However, how the dimensionless empirical parameter β depends on temperature, pressure, and composition remains poorly constrained. Viscosity and electrical conductivity are two fundamental dynamical properties of silicate melts needed to constrain melt distribution in Earth's interior but remain unclear for most …


Barriers To And Uncertainties In Understanding And Quantifying Global Critical Mineral And Element Supply, Brian A. Mcnulty, Simon M. Jowitt Jul 2021

Barriers To And Uncertainties In Understanding And Quantifying Global Critical Mineral And Element Supply, Brian A. Mcnulty, Simon M. Jowitt

Geoscience Faculty Research

The critical minerals and elements are natural substances that are essential to modern life but have insecure supply. This lack of a secure supply clashes with the increasing importance of these elements, especially given their use in technologies needed to reduce global CO2 emissions and mitigate against anthropogenic climate change. In this contribution we review the by-product nature of the critical minerals and elements and the inherant uncertainties in reported critical mineral and element annual production as well as the relationships between these commodities and main-product metals and associated concentrates. We explore the geological and geographical barriers to critical mineral …


Geological And Geochemical Analysis Of Phosphorus Bearing Minerals And Natural Glasses On Earth And In Meteorites: Implications Of The Origin Of Life, Tian Feng Jun 2021

Geological And Geochemical Analysis Of Phosphorus Bearing Minerals And Natural Glasses On Earth And In Meteorites: Implications Of The Origin Of Life, Tian Feng

USF Tampa Graduate Theses and Dissertations

Phosphorus is a key element in biogenic molecules and the mineral schreibersite is a major reactive phosphorus source for organic compounds on the prebiotic Earth. In this dissertation, a suite of reactions of phosphorus species, which originate from schreibersite minerals on chondrite meteorites and on the early Earth, have been studied to determine the intermediate geochemical pathways between phosphides and common minerals on meteorites and on the early earth.

I first investigated a unique blue fulgurite that was studied to clarify if this blue color was caused by rich phosphorus content, as has been reported for impact glasses that also …


Ware And Tear In Ancient Tampa Bay: Ceramic Elemental Analyses From Pinellas County Sites, Mckenna Loren Douglass Jun 2021

Ware And Tear In Ancient Tampa Bay: Ceramic Elemental Analyses From Pinellas County Sites, Mckenna Loren Douglass

USF Tampa Graduate Theses and Dissertations

This research tested a null hypothesis on whether ceramics from a variety of archaeological sites around the Pinellas County peninsula were sourced locally for their materials. The sites in this study include Weeden Island (8PI1-5-6-A/B/C/D), Bayshore Homes (8PI41), Yat Kitischee (8PI1753), and Maximo Point (8PI19). Since there were multiple sites that I assessed in the Tampa Bay, Florida area, I focused on one cultural period, Safety Harbor (AD 900-1500), and the ceramics created during it at the various locations. My research questions included: Were materials locally sourced for ceramic production at each of these sites? If not, what is the …


Archaeology And Seasonality Of Stock Island (8mo2), A Glades-Tradition Village On Key West, Ryan M. Harke Jun 2021

Archaeology And Seasonality Of Stock Island (8mo2), A Glades-Tradition Village On Key West, Ryan M. Harke

USF Tampa Graduate Theses and Dissertations

Later Glades-period cultures (ca. 500–1760 CE) of south Florida and the Florida Keys are understudied and thus poorly understood, especially those that pre-date the arrival of Spaniards to the New World. Recent archaeological models of their sociopolitical organization suggest that by the Glades I-II transition (750/800 CE), south Florida peoples were organized into what appear to be regional population centers (e.g., Pineland and Mound Key, Granada, Turner River) and smaller hinterland towns in the Everglades (e.g., Cane Patch, Bear Lake) and the Florida Keys (e.g., Stock Island, Clupper Site). Smaller towns are hypothesized to be sedentary, heterarchically-organized, simple chiefdoms from …


Calcium Isotope Cosmochemistry, Maria C. Valdes, Katherine R. Bermingham, Shichun Huang, Justin I. Simon Jun 2021

Calcium Isotope Cosmochemistry, Maria C. Valdes, Katherine R. Bermingham, Shichun Huang, Justin I. Simon

Geoscience Faculty Research

The past decade has seen significant advancements in analytical capabilities and with it a marked increase in the use of Ca isotopes to advance our understanding of the Solar System's and Earth's evolution. Here, mass-dependent and non-mass-dependent Ca isotopic variations in bulk meteorites and chondrite components are discussed. This contribution also examines how Ca isotopes record nebular processes, including evaporation/condensation and mixing of chemically and isotopically distinct reservoirs in the protoplanetary disk. The applicability of non-mass-dependent Ca isotopic variations to tracing the nature and timing of stellar mass contributions to the parental molecular cloud is discussed. This includes the constraints …


Characterization Of Surface Geology And Hydrogeology In The Upper Ulua River Basin, Honduras, C. Renee Sparks, Issac J. Jacques, Cheryl L. Verbree, Thomas J. Timmermans, Stuart Dykstra May 2021

Characterization Of Surface Geology And Hydrogeology In The Upper Ulua River Basin, Honduras, C. Renee Sparks, Issac J. Jacques, Cheryl L. Verbree, Thomas J. Timmermans, Stuart Dykstra

The Compass: Earth Science Journal of Sigma Gamma Epsilon

This research includes a hydrogeologic assessment in and around La Union, Honduras to determine the contribution of groundwater to the surface water system and understand the geological control of groundwater storage and movement. Field methods were employed and focused on spring characterization, geochemical signatures, and structural data. Field data was gathered, and locations determined using cellular-integrated GPS signal and the Fulcrum mapping software mobile application. During the summer of 2017, data on 111 geologic points and 34 water points were collected to understand the hydrogeology of the region. Streams and springs were monitored for pH, flow characteristics and conductance as …


Past Ice-Ocean Interactions On The Sabrina Coast Shelf, East Antarctica: Deglacial To Recent Paleoenvironmental Insights From Marine Sediments, Kara J. Vadman May 2021

Past Ice-Ocean Interactions On The Sabrina Coast Shelf, East Antarctica: Deglacial To Recent Paleoenvironmental Insights From Marine Sediments, Kara J. Vadman

USF Tampa Graduate Theses and Dissertations

The East Antarctic Ice Sheet (EAIS) contains ~53 meters of sea level equivalent (SLE) ice, and observations suggest it is sensitive to ongoing and past climate change. The EAIS has traditionally been considered insensitive to climate perturbations because it is largely grounded above sea level. However, aerogeophysical surveys, oceanographic observations, and models indicate that large areas of the EAIS are grounded below sea level and contain 19.2 m SLE. Marine-based parts of the EAIS are thought to be located on inland-sloping beds that drain through marine terminating outlet glaciers, indicating large areas of the EAIS may be more sensitive to …


The Impact Of Burning On The Structure And Mineral Composition Of Bat Guano, Joyce Lundberg, Donald A. Mcfarlane May 2021

The Impact Of Burning On The Structure And Mineral Composition Of Bat Guano, Joyce Lundberg, Donald A. Mcfarlane

International Journal of Speleology

Here we addressed the question of whether burning of guano produces a characteristic suite of morphological changes and/or unique mineralogical products. The changes observed in our experimental burning of guano (both fresh and decayed) included colour change (blackening), grain size and morphological change (grain size generally reduced, morphology rendered generally less distinct), alteration of minerals by dehydration (e.g., gypsum to anhydrite, brushite to whitlockite), and production of new minerals or compounds (e.g., augelite, bayerite, giniite, graphite, oldhamite, strontium apatite, tridymite). The key morphological feature we found that may be diagnostic of burning was severe damage to crystals from rapid dehydration …


Carbonate Paleothermometry In Fayetteville Green Lake, New York, Micah Wiesner May 2021

Carbonate Paleothermometry In Fayetteville Green Lake, New York, Micah Wiesner

Theses - ALL

Lacustrine carbonates are important paleoclimate archives, but unknowns in the seasonal timing and depth of precipitation obscure the interpretation of temperatures associated with them. The clumped isotope paleothermometer records the formation temperature T(D47) of carbonates. This study examines a set of lacustrine carbonates formed in the water column, in addition to carbonate from a sediment core, to better understand the depth and seasonality of carbonate formation in a lacustrine setting. We test that, regardless of season and formation temperature, lacustrine carbonates form in isotopic equilibrium with respect to D47 and d18O fractionation. Further, we account for the effect of our …


Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-Temperature Magmatic Conditions And Non-Laurentian Origin Of Earth's Most Zircon Fertile Magmas, Kyle Makovsky May 2021

Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-Temperature Magmatic Conditions And Non-Laurentian Origin Of Earth's Most Zircon Fertile Magmas, Kyle Makovsky

Dissertations - ALL

The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to and after the Grenville. To investigate this further, Mesoproterozoic basement rocks were sampled along the axis of the current Appalachian Mountains from western North Carolina north to southern New York, as well as from the northern Andes in southern Colombia. Zircon was extracted from these rocks to exploit its propensity to incorporate several isotopic tracers useful in determining …


Carbonate Paleothermometry In Fayetteville Green Lake, New York, Micah Wiesner May 2021

Carbonate Paleothermometry In Fayetteville Green Lake, New York, Micah Wiesner

Theses - ALL

Lacustrine carbonates are important paleoclimate archives, but unknowns in the seasonal timing and depth of precipitation obscure the interpretation of temperatures associated with them. The clumped isotope paleothermometer records the formation temperature T(D47) of carbonates. This study examines a set of lacustrine carbonates formed in the water column, in addition to carbonate from a sediment core, to better understand the depth and seasonality of carbonate formation in a lacustrine setting. We test that, regardless of season and formation temperature, lacustrine carbonates form in isotopic equilibrium with respect to D47 and d18O fractionation. Further, we account for the effect of our …


Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-Temperature Magmatic Conditions And Non-Laurentian Origin Of Earth’S Most Zircon Fertile Magmas, Kyle Makovsky May 2021

Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-Temperature Magmatic Conditions And Non-Laurentian Origin Of Earth’S Most Zircon Fertile Magmas, Kyle Makovsky

Dissertations - ALL

The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to and after the Grenville. To investigate this further, Mesoproterozoic basement rocks were sampled along the axis of the current Appalachian Mountains from western North Carolina north to southern New York, as well as from the northern Andes in southern Colombia. Zircon was extracted from these rocks to exploit its propensity to incorporate several isotopic tracers useful in determining …


Changes In Tropospheric Ozone Associated With Strong Earthquakes And Possible Mechanism, Feng Jing, Ramesh P. Singh May 2021

Changes In Tropospheric Ozone Associated With Strong Earthquakes And Possible Mechanism, Feng Jing, Ramesh P. Singh

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The index of ozone anomaly (IOA) has been proposed to detect changes in tropospheric ozone associated with strong earthquakes. The tropospheric ozone prior and after the 2008 Wenchuan earthquake has been analyzed using IOA. Atmospheric infrared sounder ozone volume mixing ratio (O3 VMR) at different pressure levels (600, 500, 400, 300, 200 hPa) for an 18-year period 2003–2020 has been considered to identify the unique behavior associated with the strong earthquakes. Our results show distinct enhancement in tropospheric ozone occurred 5 d (7 May 2008) prior to the main event and distributed along the Longmenshan fault zone. An enhancement in …


Local- And Regional-Scale Forcing Of Glacier Mass Balance Changes In The Swiss Alps, Saeideh Gharehchahi, Thomas J. Ballinger, Jennifer L.R. Jensen, Anshuman Bhardwaj, Lydia Sam, Russell C. Weaver, David R. Butler May 2021

Local- And Regional-Scale Forcing Of Glacier Mass Balance Changes In The Swiss Alps, Saeideh Gharehchahi, Thomas J. Ballinger, Jennifer L.R. Jensen, Anshuman Bhardwaj, Lydia Sam, Russell C. Weaver, David R. Butler

Research, Publications & Creative Work

Glacier mass variations are climate indicators. Therefore, it is essential to examine both winter and summer mass balance variability over a long period of time to address climate-related ice mass fluctuations. In this study, we analyze glacier mass balance components and hypsometric characteristics with respect to their interactions with local meteorological variables and remote large-scale atmospheric and oceanic patterns. The results show that all selected glaciers have lost their equilibrium condition in recent decades, with persistent negative annual mass balance trends and decreasing accumulation area ratios (AARs), accompanied by increasing air temperatures of +0.45 C decade 1. The controlling factor …


Interaction Of Aqueous U(Vi) With Goethite, Montmorillonite, And Uo2(S), Anshuman Satpathy May 2021

Interaction Of Aqueous U(Vi) With Goethite, Montmorillonite, And Uo2(S), Anshuman Satpathy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Uranium contamination in subsurface environments is a matter of great concern throughout the world. Fate and transport of uranium in the subsurface can be controlled by U(VI) adsorption and reduction onto common iron (oxy)hydroxides and clay minerals. Aqueous U(VI) can also exchange uranium atoms with solids comprised of uranium which can potentially lead to changes in the morphology of the uranium-containing solids and affect their stability. First, the performance of multiple surface complexation models (SCMs) on adsorption of U(VI) onto goethite was analyzed for a broad range of input conditions. Individual models could fit the data for which they were …


Dolomite Stoichiometry As A Proxy For Fluid Chemistry, Cameron J. Manche May 2021

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 …


A Triple Oxygen Isotope Analysis Of Altered Oceanic Crust And Its Buffering Effect On The Steady State Oxygen Isotope Composition Of Seawater, Jesse P. Mcgunnigle May 2021

A Triple Oxygen Isotope Analysis Of Altered Oceanic Crust And Its Buffering Effect On The Steady State Oxygen Isotope Composition Of Seawater, Jesse P. Mcgunnigle

Earth and Planetary Sciences ETDs

The secular chemical marine sediment trend showing an increase in δ18O over geologic time has traditionally been investigated using δ18O modelling of ancient ocean compositions, ocean surface temperatures, and sample diagenetic alteration. This study presents a triple oxygen isotope mass balance for the oceans using high precision δ18O and Δ'17O measurements of altered oceanic crust. The mass balance model predicts an ice-free seawater with δ18O = -0.29‰ and Δ’17O = -0.002‰ with steady state reached at approximately (0.5 to 1)×109 years. Modifications to the hydrothermal alteration and …