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

Geochemistry Commons

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

1,784 Full-Text Articles 3,379 Authors 562,452 Downloads 120 Institutions

All Articles in Geochemistry

Faceted Search

1,784 full-text articles. Page 38 of 67.

Walker Lake Basin Data, Larry Benson, Steve P. Lund 2017 U.S. Geological Survey

Walker Lake Basin Data, Larry Benson, Steve P. Lund

Data Sets for USGS Research

Walker Lake Basin Data

Name Date modified Time modified Size MB Extension

Walker Lake Core 84-8 isotope and age data.xls 27.01.2018 15:25:52 0.03 xls

Walker Lake core WL002 PSV age and chemical data.xlsx 09.02.2018 20:04:50 0.03 xlsx

In the Walker Lake Basin folder:

Depth, 14C age (not corrected for reservoir effect), 18O, 13C data for core 84-8 are reported in:

Benson, L.V., 1988, Preliminary paleolimnologic data for the Walker Lake subbasin, California and Nevada: U.S. Geological Survey Water-Resources Investigations Report 87-4258, 50p. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 240, p. 497-507.

Depth, PSV age, TIC , 18O, 13 …


Pyramid Lake Core Data, Larry Benson 2017 U.S. Geological Survey

Pyramid Lake Core Data, Larry Benson

Data Sets for USGS Research

Pyramid Lake Core Data

14C and calibrated ages for core PLC08-1.xlsx 01.03.2014 19:45:30 0.01 xlsx

14C and calibrated ages for core PLC92B.xlsx 04.03.2014 16:41:30 0.01 xlsx

14C and calibrated ages for core PLC97-3.xlsx 01.03.2014 19:50:48 0.01 xlsx

CalKa Depth TOC TIC 18O 13C for PLC97-1.xlsx 09.11.2017 20:51:22 0.04 xlsx

Depth 14CAge Corrected 14C AGE CAL Age PLC98-4.xlsx 15.11.2017 18:26:12 0.01 xlsx

Depth 180 13C TOTC TOC TIC porosity CYBP Box Core PLB98-2.xlsx 01.03.2014 20:00:46 0.01 xlsx

Depth CalAge TIC TOTC TOC 13C 18O PLC98-4.xlsx 02.03.2014 00:32:20 0.05 xlsx

Depth Equivalent Depth in PLC08-1 PSV age 180 13C TIC TOC for …


A Geochemical Investigation And Comparison Between Organic-Rich Black Shales And Mississippi Valley-Type Pb-Zn Ores In The Southern Ozarks Region, Bryan Michael Bottoms 2017 University of Arkansas, Fayetteville

A Geochemical Investigation And Comparison Between Organic-Rich Black Shales And Mississippi Valley-Type Pb-Zn Ores In The Southern Ozarks Region, Bryan Michael Bottoms

Graduate Theses and Dissertations

Mississippi Valley-type (MVT) deposits are base metal sulfide deposits that are important economic sources of both Pb and Zn, accounting for 24% of the global Pb and Zn reserves. They are found all over the world, often hosted in platform carbonates on the flanks of sedimentary basins, and often in proximity to hydrocarbons. They are epigenetic, not related to igneous activity, and thought to be sourced from low temperature, highly saline basinal brines that are expelled from sedimentary basins during compaction and/or in conjunction with an orogenic event. The basinal lithologies responsible for providing the metals for the ores are …


Rock Magnetic Investigation Of The Michigan Basin Soils And Sediments Overlying The Oil-Bearing Silurian Pinnacle Reefs, Jake Tresnak 2017 Michigan Technological University

Rock Magnetic Investigation Of The Michigan Basin Soils And Sediments Overlying The Oil-Bearing Silurian Pinnacle Reefs, Jake Tresnak

Dissertations, Master's Theses and Master's Reports

A relationship between the hydrocarbon migration and magnetic properties of near-surface sediments was investigated from several hundreds of samples collected over the hydrocarbon-bearing Silurian pinnacle reef belt of the Michigan Basin. The collected samples were investigated using several rock magnetic methods and optical microscopy. The investigation has not revealed a straightforward relationship between the magnetic susceptibility and hydrocarbon reservoirs within the reef belt; both anomalously high and low susceptibility values were observed. The elevated values are associated with newly formed magnetite in the form of spheroidal grains produced by hydrocarbon-related diagenesis while the extremely low susceptibilities may reflect dissolution of …


Gypsum, Calcite, And Dolomite Caprock Fabrics And Geochemistry From The Gypsum Valley Salt Diapir, Paradox Basin, Southwestern Colorado, Kevin Lerer 2017 University of Texas at El Paso

Gypsum, Calcite, And Dolomite Caprock Fabrics And Geochemistry From The Gypsum Valley Salt Diapir, Paradox Basin, Southwestern Colorado, Kevin Lerer

Open Access Theses & Dissertations

Caprocks are found on top of or in a lateral position relative to salt diapirs. The caprocks predominantly comprise sulfate minerals such as anhydrite or gypsum, which presumably accreted during the dissolution of salt from evaporite sediments. In some cases, the sulfate minerals are replaced by carbonate minerals, referred to as "carbonate caprock". Carbonate caprocks associated with salt diapirs are important because they can act as reservoirs or conduits for hydrocarbons, and because they can be easily misidentified as carbonate lithologies belonging to the stratigraphy of the sedimentary sequences adjacent to the diapir, which can jeopardize the accurate interpretation of …


Genesis Of Unique Carbonate Fans In A Pre-Salt Reservoir Analogue, Indio Mountains, West Texas, Andre Llanos 2017 University of Texas at El Paso

Genesis Of Unique Carbonate Fans In A Pre-Salt Reservoir Analogue, Indio Mountains, West Texas, Andre Llanos

Open Access Theses & Dissertations

Hydrocarbon exploration in pre-salt sediments of rift basins on the South Atlantic Margin have proven to be successful major oil plays. Located on the western margin of the rift, the Brazilian pre-salt reservoirs of the Santos, Campos, and Espirito Santo Basins are hosted by lacustrine/marine-influenced carbonates that comprise laterally extensive, laminated microbialite facies. The Indio Mountains, located in West Texas, provide well-exposed outcrops of Lower Cretaceous marine and non-marine rift basin strata that can be considered a reservoir-analog to the South Atlantic Margin pre-salt facies. Of particular interest for hydrocarbon exploration are unique carbonate features that have been discovered in …


Evaluation Of Cryptic Sulfur Cycling In Marine Sediments, Michael Ngari Mathuri 2017 University of Texas at El Paso

Evaluation Of Cryptic Sulfur Cycling In Marine Sediments, Michael Ngari Mathuri

Open Access Theses & Dissertations

Despite the importance of marine sediments as a carbon sink and many efforts to integrate microbiological with geochemical and geological data, the understanding of microbial organic carbon mineralization processes in marine sediments remains incomplete. There is growing evidence for the existence of an unrecognized oxidative sulfur cycling (cryptic sulfur cycling) above, within and below of the main sulfate reduction zone. For example, sulfate exists in supposedly sulfate-free methanogenic marine sediments from the Aarhus Bay and Black Sea. This implies that sulfur cycling is an ongoing process in the deep biosphere. Quantification of cryptic sulfur cycling is a major challenge because …


Cycling Of Gypsiferous White Sands Aerosols In The Shallow Critical Zone At White Mountain, New Mexico, Patrick Richard Rea 2017 University of Texas at El Paso

Cycling Of Gypsiferous White Sands Aerosols In The Shallow Critical Zone At White Mountain, New Mexico, Patrick Richard Rea

Open Access Theses & Dissertations

Dry deposition significantly affects evolution of the critical zone by nutrient supply and contributing to soil genesis. Dust influx and cycling in soils are difficult to quantify because dust sources can be chemically similar to local soils. White Sands, New Mexico, emits gypsum dust with a unique chemical and isotopic signature, providing an opportunity to investigate dust deposition and its movement in soils. This study evaluated the mobility of White Sands dust particles in the critical zone at White Mountain, New Mexico, a highland 100 km downwind. Four soil profiles were collected over limestone, igneous, mixed limestone and dolostone, and …


Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole 2017 The University of Akron

Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole

Williams Honors College, Honors Research Projects

A series of three sediment cores were collected in Lake Tanganyika, Africa, and were analyzed for mercury concentrations. For all three cores, a decrease in mercury (Hg) levels was observed from the 1600’s (appx. 20 ng/g) until concentrations reached a minimum during the mid-1800’s (appx. 10 ng/g). The mid-1800’s marked a change from decreasing mercury levels to an increase over the following century. The core tops (circa 2006) have concentrations greater than 70 ng/g. The onset of the rise in mercury concentrations coincides with the beginning of the Industrial Revolution in the mid to late 18th century. Relationships between …


Dam Removal In The Usa: Effects On River Water Quality, Michael A. Kruge 2017 Montclair State University

Dam Removal In The Usa: Effects On River Water Quality, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Dam removal decisions should ideally be made after a thorough cost-benefit analysis. If dam obsolescence, structural safety, harm to fisheries, maintenance costs, and reservoir eutrophication are among the primary concerns, decommissioning would likely be favored. On the other hand, dams provide considerable benefits including water storage for agricultural and urban consumption, renewable electricity generation, support of navigational canal systems, flood control, and lakes for recreation. Because of these competing factors and interests, dam removal decision-making in the United States is often a slow process fraught with controversy, as in the case of the Klamath River.

Dams provided mechanical water power …


Isotope Investigation Of Nitrate In Soils And Agricultural Drain Waters Of The Lower Yakima Valley, Washington, Dallin Jensen 2017 Central Washington University

Isotope Investigation Of Nitrate In Soils And Agricultural Drain Waters Of The Lower Yakima Valley, Washington, Dallin Jensen

All Master's Theses

Nitrate in the groundwater of the Lower Yakima Valley, Washington has long been known to frequently exceed the EPA maximum contaminant level standard for potable water (10 mg/L), adversely impacting communities with disadvantaged socio-economic status. In this research, nitrogen and oxygen isotopic signatures were determined for nitrate soil leachates and irrigation return flow collected in the Lower Yakima Valley, Washington and compared to previous isotopic studies of nitrate in Central Washington. δ15N, δ18O and Δ17O values are used to constrain sources of to groundwater. Isotope signatures for nitrate from soil leachate largely overlapped with …


Community Production Modulates Coral Reef Ph And The Sensitivity Of Ecosystem Calcification To Ocean Acidification, Thomas M. Decarlo, Anne L. Cohen, George T. F. Wong, Fuh-Kwo Shiah, Steven J. Lentz, Kristen A. Davis, Kathryn E. F. Shamberger, Pat Lohmann 2017 Old Dominion University

Community Production Modulates Coral Reef Ph And The Sensitivity Of Ecosystem Calcification To Ocean Acidification, Thomas M. Decarlo, Anne L. Cohen, George T. F. Wong, Fuh-Kwo Shiah, Steven J. Lentz, Kristen A. Davis, Kathryn E. F. Shamberger, Pat Lohmann

OES Faculty Publications

Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals, and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a 2 week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the nonbleaching period was ~8.5, significantly elevated above that of the surrounding open ocean (~8.0-8.1) as …


Effects Of Nonaerated Circulation Water Velocity On Nutrient Release From Aquaculture Pond Sediments, Xiangju Cheng, Dantong Zhu, XiXi Wang, Deguang Yu, Jun Xie 2017 Old Dominion University

Effects Of Nonaerated Circulation Water Velocity On Nutrient Release From Aquaculture Pond Sediments, Xiangju Cheng, Dantong Zhu, Xixi Wang, Deguang Yu, Jun Xie

Civil & Environmental Engineering Faculty Publications

Sustaining good water quality in aquaculture ponds is vital. Without an aerator, the dissolved oxygen in ponds comes primarily from mass transfer at the water-ambient atmosphere interface. As sediment can seriously affect water quality, this study used indoor experiments to examine the nutrient (nitrogen and phosphorus) release mechanisms and fluxes from sediment in aquaculture ponds with moving water but no aeration. The results showed that the ammonia nitrogen (NH3-N) concentration in the overlying water was inversely proportional to flow velocity and that a higher flow velocity tended to result in a lower concentration in the overlying water, a …


Introducing Global Peat-Specific Temperature And Ph Calibrations Based On Brgdgt Bacterial Lipids, B.D.A. Naafs, G. N. Imglis, Y. Zheng, M. J. Amesbury, H. Biester, R. Bindler, J. Blewett, M. A. Burrows, D. del Castillo Torres, F. M. Chambers, P. G. Hatcher 2017 Old Dominion University

Introducing Global Peat-Specific Temperature And Ph Calibrations Based On Brgdgt Bacterial Lipids, B.D.A. Naafs, G. N. Imglis, Y. Zheng, M. J. Amesbury, H. Biester, R. Bindler, J. Blewett, M. A. Burrows, D. Del Castillo Torres, F. M. Chambers, P. G. Hatcher

Chemistry & Biochemistry Faculty Publications

Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (−8 to 27 °C) and pH (3–8) range …


A Miniaturized Spectrophotometric In Situ Ph Sensor For Seawater, Reuben C. Darlington 2017 The University Of Montana

A Miniaturized Spectrophotometric In Situ Ph Sensor For Seawater, Reuben C. Darlington

Graduate Student Theses, Dissertations, & Professional Papers

Since the Industrial Revolution, the world's oceans have absorbed increasing amounts of CO2 and the resultant changes to the marine carbonate chemical system have reduced the pH by > 0.1 units (~ 30%) in surface waters. This acidification of the oceans has many far reaching impacts on marine life and there is great need of quality instrumentation to assess and follow the changing carbonate system. This MIS project aims to develop a low cost pH sensor with high precision and accuracy for open sea measurements with special emphasis on reduced size and cost. Design effort is based on the commercially available …


Effects Of Titanomagnetite Reordering Processes On Thermal Demagnetization And Paleointensity Experiments, Julie A. Bowles, Mike J. Jackson 2016 University of Wisconsin-Milwaukee

Effects Of Titanomagnetite Reordering Processes On Thermal Demagnetization And Paleointensity Experiments, Julie A. Bowles, Mike J. Jackson

Geosciences Faculty Articles

Titanomagnetite (Fe3-xTixO4, 0≤x≤1) is a common, naturally occurring magnetic mineral critical to many paleomagnetic studies. Underlying most interpretations is the assumption that, lacking chemical alteration, Curie temperature (Tc) remains constant. However, recent work has demonstrated that Tc of many natural titanomagnetites varies strongly as a function of thermal history, independent of chemical alteration. This is inferred to arise from reordering of cations and/or vacancies in the crystal structure, and changes occur at temperatures and times relevant to standard paleomagnetic thermal treatments. Because changes take place at Tc, …


An Evaluation Of The Lithologies And Geochemistry Of The Upper Beaver Deposit Of The Kirkland Lake Area, Katherine E. Feick 2016 The University of Western Ontario

An Evaluation Of The Lithologies And Geochemistry Of The Upper Beaver Deposit Of The Kirkland Lake Area, Katherine E. Feick

Electronic Thesis and Dissertation Repository

The Upper Beaver Cu-Au deposit contains a unique style of mineralization in the Larder Lake and Kirkland Lake areas in terms of mineralization, alteration style, and age. This study aims to use company-provided data, supplemented with focused data collection, to evaluate what information can be attained from company-provided geochemical data. The evaluation uses a combination of hand sample, petrographic, geochemical, statistical, and microprobe analytical methods.

Lithogeochemical analyses indicated that the altered igneous host rock is calc-alkaline in composition and is most likely part of the diorite-monzonite suite. Further, exploratory data analysis of Au and Cu mineralization identified that there are …


Geothermometry Of Two Cascade Geothermal Systems, Donnel Alexander Malkemus 2016 Portland State University

Geothermometry Of Two Cascade Geothermal Systems, Donnel Alexander Malkemus

Dissertations and Theses

For this thesis I applied classical and multi-component geothermometry techniques to new water chemistry data from Breitenbush Hot Springs, Oregon and the Wind River Valley, Washington. A total of 20 well, spring, and stream samples from Breitenbush Hot Springs and 4 spring samples from the Wind River Valley were collected and analyzed for major, minor, and select trace anions and cations, as well as stable oxygen and hydrogen isotopes. I used two computer programs, GeoT and RTEst, to conduct multi-component geothermometry reservoir condition estimation on each water sample. Water chemistry data from Breitenbush Hot Springs indicates a range of thermal, …


Sedimentology And Geochemistry Of The Mixed Carbonate-Siliciclastic Espanola Formation, Paleoproterozoic Huronian Supergroup, Bruce Mines-Elliot Lake Area, Ontario, Canada, Mansour H. Al-Hashim 2016 The University of Western Ontario

Sedimentology And Geochemistry Of The Mixed Carbonate-Siliciclastic Espanola Formation, Paleoproterozoic Huronian Supergroup, Bruce Mines-Elliot Lake Area, Ontario, Canada, Mansour H. Al-Hashim

Electronic Thesis and Dissertation Repository

The Espanola Formation of the Paleoproterozoic Huronian Supergroup is a mixed carbonate-siliciclastic succession. Detailed sedimentological analysis of the formation in the Bruce Mines-Elliot Lake region reveals 17 sedimentary lithofacies, which comprise three distinct lithofacies associations. The lithofacies associations represent, in ascending order, shoreface, offshore, and nearshore (or lagoon) depositional environments along a wave- and storm-dominated shallow siliciclastic marine shelf. Major, trace, and rare earth element analyses of the siliciclastic component indicate derivation from a mainly granodioritic Archean upper continental crust with some contributions from mafic volcanic and/or sedimentary rocks. The results show that the source rocks were subjected to relatively …


Temporal Co2 Variations And The Influence Of Bat Colonies In Speleogenesis: Continuous Co2 Monitoring In War Eagle Cavern, Arkansas, Ginny Sue Holcomb 2016 University of Arkansas, Fayetteville

Temporal Co2 Variations And The Influence Of Bat Colonies In Speleogenesis: Continuous Co2 Monitoring In War Eagle Cavern, Arkansas, Ginny Sue Holcomb

Graduate Theses and Dissertations

Dissolved concentrations of CO2 in a karst aquifer are a major control on calcite dissolutional processes, as CO2 combines chemically with water to form carbonic acid. As increasing amounts of CO2 are added to the system, greater resultant water aggressivity generates greater rates of dissolution. Spatial and temporal variations in carbon flux through the system may occur over a range of time scales, and high-resolution data collection is needed to truly understand and characterize such variability. Continuous CO2 monitoring in War Eagle Cavern, Arkansas, will suggest a number of influential parameters with varying degrees of importance throughout an annual cycle. …


Digital Commons powered by bepress