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

Geochemistry Commons™

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

1,546 Full-Text Articles 3,127 Authors 825,274 Downloads 110 Institutions

All Articles in Geochemistry

Faceted Search

1,546 full-text articles. Page 36 of 60.

Occupational Seasonality And Paleoenvironmental Reconstruction At Quebrada Jaguay 280, Stephanie Melissa Gruver 2018 Northern Illinois University

Occupational Seasonality And Paleoenvironmental Reconstruction At Quebrada Jaguay 280, Stephanie Melissa Gruver

Graduate Research Theses & Dissertations

Quebrada Jaguay 280 (QJ-280) is one of the oldest maritime archaeological sites in the New World. Previous excavations of the southern Peruvian coastal site have dated occupation from ~13,000-8,000 cal yr BP. These excavations also determined that the occupants of the site used preferential maritime resource procurement strategies and had an interzonal connection to the highlands. In 2017 a new excavation was conducted at QJ-280 and the remains of the marine mollusk Mesodesma donacium were recovered. Geochemical examinations on the shell remains informed on the occupational seasonality of the site and reconstructed sea surface temperatures experienced off the coast of …


A Combined Field, Experimental And Modeling Approach To Understand The Impacts Of Flood Irrigation On Pedogenic Caco3 And Co2 Dynamics In Drylands, Anna Cristina Ortiz 2018 University of Texas at El Paso

A Combined Field, Experimental And Modeling Approach To Understand The Impacts Of Flood Irrigation On Pedogenic Caco3 And Co2 Dynamics In Drylands, Anna Cristina Ortiz

Open Access Theses & Dissertations

Soil salinization is a global problem affecting 10% of agricultural soils, particularly in irrigated arid-lands. This study investigated salt loading through flood-irrigation, particularly of calcite (CaCO3) salt in the southwest of the United States. To evaluate the impact that flood-irrigation has on CaCO3 buildup and its effect on C-cycling, a natural soil and two agricultural soils were sampled: a pecan orchard and an alfalfa field in the El Paso, TX region. Agricultural soils in this study are flood irrigated by the Rio Grande river and by ground waters in its absence, both of which are oversaturated with calcite.

To trace …


Trace Metal And Metalloid Behavior In The Submicron Scale Components Of Coal Fly Ashes: Insights From Combined Microscopic And Microbiological Studies, Matthew Costa 2018 University of Texas at El Paso

Trace Metal And Metalloid Behavior In The Submicron Scale Components Of Coal Fly Ashes: Insights From Combined Microscopic And Microbiological Studies, Matthew Costa

Open Access Theses & Dissertations

For over a century, coal has been used worldwide to meet ever-growing energy demands. Coal combustion accounts for over 30% of electricity generation in the United States. In the U.S., coal combustion produces annually over 100 million tons of coal combustion products (CCPs) of which only 30% are used in beneficial and economic ways. One of the primary CCPs from coal-burning power plants is fly ash, typically fine-sized and enriched in many trace elements (e.g., arsenic, chromium, lead, and vanadium). When disposed in the environment, fly ash may release significant concentrations of trace elements into surrounding ecosystems and induce toxicity …


Geostatistical And Geospatial Distribution Of Multiple Metallic Elements In Agricultural Regions Of The Mid-Continental Usa, Najwah Alssaeidi Ahmed Almesleh 2018 University of Texas at El Paso

Geostatistical And Geospatial Distribution Of Multiple Metallic Elements In Agricultural Regions Of The Mid-Continental Usa, Najwah Alssaeidi Ahmed Almesleh

Open Access Theses & Dissertations

Regional geochemical mapping constitute the chemistry of the surface of the earth in a large scale and relatively low sample density. It is widely accepted scientific activity and man uses some cases to identify contamination. In the present study, data present in national geochemical survey database was used to investigate the chemical loading loading of the agricultural soil. In the mid-continent region of the United States. Several traditional parameters were used mainly the enrichment factor (EF), and geoaccumulation index (I geo). Total chemical influence (TCI) maps were used to guide sampling. In addition, regional trace element chemistry of bedrock was …


Evidence For Ephemeral Middle Eocene To Early Oligocene Greenland Glacial Ice And Pan-Arctic Sea Ice, Aradhna Tripati, Dennis Darby 2018 Old Dominion University

Evidence For Ephemeral Middle Eocene To Early Oligocene Greenland Glacial Ice And Pan-Arctic Sea Ice, Aradhna Tripati, Dennis Darby

OES Faculty Publications

Earth's modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO2 …


Spatial And Temporal Analysis Of Surface Water Quality In Relation To Marcellus Shale Gas Development In The Northern Panhandle Of West Virginia, Rachel Yesenchak 2018 West Virginia University

Spatial And Temporal Analysis Of Surface Water Quality In Relation To Marcellus Shale Gas Development In The Northern Panhandle Of West Virginia, Rachel Yesenchak

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pre-existing water chemistry data available from the West Virginia Department of Environmental Protection were used to examine temporal changes in surface water quality related to the onset of Marcellus Shale gas drilling activity in the state of West Virginia. Drilling is concentrated in the northwestern portion of the state. Watersheds were delineated for twelve discrete stream sampling locations in the Upper Ohio-Wheeling HUC-8 sub-basin, where shale gas drilling is prevalent. Kruskal-Wallis tests were deployed to compare pre- and post-drilling concentrations of conductivity, chloride, and total suspended solids for each location. Increased concentrations of these parameters are associated with surface water …


Photochemical Cycling Of Reactive Oxygen Species In Hydrothermal Systems: Impacts On Biosignature Preservation, Megan A. Mave 2018 University of Montana

Photochemical Cycling Of Reactive Oxygen Species In Hydrothermal Systems: Impacts On Biosignature Preservation, Megan A. Mave

Graduate Student Theses, Dissertations, & Professional Papers

Life originated on early Earth, despite harsh, highly reducing conditions. Life may have also emerged on early Mars, when conditions on the two planets were similar (i.e. before atmosphere loss and desiccation). NASA’s 2020 Mars rover mission aims to identify biosignatures (i.e. evidence of life) in early Martian deposits. Potential exploration sites include extinct hydrothermal springs, due to their high habitability and preservation potential. This study aims to better understand biosignature preservation in hydrothermal systems analogous to those on early Mars (i.e. reducing and Fe-rich).

Reactive oxygen species (ROS) are highly reactive molecules formed primarily by photochemical reactions. ROS are …


Using Multiple Environmental Tracers To Investigate The Relative Role Of Soil And Deep Groundwater In Stream Water Generation For A Snow-Dominated Headwater Catchment, Isabellah V. von Trapp 2018 University of Montana, Missoula

Using Multiple Environmental Tracers To Investigate The Relative Role Of Soil And Deep Groundwater In Stream Water Generation For A Snow-Dominated Headwater Catchment, Isabellah V. Von Trapp

Graduate Student Theses, Dissertations, & Professional Papers

In this study, seasonal fluctuation of environmental tracers in stream flow, soil water, and deep bedrock groundwater were used to constrain the role of deep bedrock groundwater in streamflow generation for a mountainous headwater catchment. Synoptic measurements of stream discharge, 222Rn, specific conductivity and major ion concentrations were measured throughout the water year over a 5 km reach of Cap Wallace Creek in the Lubrecht Experimental Forest, Montana, U.S.A. with the intention of understanding groundwater – surface water interactions across spatial and temporal scales. Stage measurements were continually recorded at seven stilling well locations along the reach. Discharge measurements …


Trace Element And Isotopic Fingerprinting Of Olivine Phenocrysts As Recorders Of Magmatic Processes In The Golden Trout Volcanic Field, Kern Plateau, Ca, Mark E. Szymanski 2018 Humboldt State University

Trace Element And Isotopic Fingerprinting Of Olivine Phenocrysts As Recorders Of Magmatic Processes In The Golden Trout Volcanic Field, Kern Plateau, Ca, Mark E. Szymanski

Cal Poly Humboldt theses and projects

Quaternary mafic volcanism in the western Basin and Range and in the southeastern Sierra Nevada is largely controlled by extensional stresses that promote magma generation through decompression melting of the lithospheric and asthenospheric mantle. Where volcanism occurs in the Sierra Nevada, like at the Golden Trout Volcanic Field GTVF), the eruption rate, number of vents, and eruption volume is an order of magnitude less than at neighboring Basin and Range volcanic fields such as the Big Pine Volcanic Field (BPVF). To determine the factors that cause these differences in adjacent and contemporaneous volcanic fields, I sampled rocks from both fields …


Evaluation Of The Community Multiscale Air Quality Model For Simulating Winter Ozone Formation In The Uinta Basin, Rebecca Matichuk, Gail Tonnesen, Deborah Luecken, Rob Gillam, Sergey L. Napelenok, Kirk R. Baker, Donna Schwede, Ben Murphy, Detlev Helmig, Seth N. Lyman, Shawn Roselle 2017 U.S. Environmental Protection Agency

Evaluation Of The Community Multiscale Air Quality Model For Simulating Winter Ozone Formation In The Uinta Basin, Rebecca Matichuk, Gail Tonnesen, Deborah Luecken, Rob Gillam, Sergey L. Napelenok, Kirk R. Baker, Donna Schwede, Ben Murphy, Detlev Helmig, Seth N. Lyman, Shawn Roselle

Bingham Research Center

The Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ) models were used to simulate a 10 day high-ozone episode observed during the 2013 Uinta Basin Winter Ozone Study (UBWOS). The baseline model had a large negative bias when compared to ozone (O3) and volatile organic compound (VOC) measurements across the basin. Contrary to other wintertime Uinta Basin studies, predicted nitrogen oxides (NOx) were typically low compared to measurements. Increases to oil and gas VOC emissions resulted in O3 predictions closer to observations, and nighttime O3 improved when reducing the deposition velocity …


Abiotic- And Biotic-Formation Of Manganese Oxides And Their Fate In Environmental Systems, Haesung Jung 2017 Washington University in St. Louis

Abiotic- And Biotic-Formation Of Manganese Oxides And Their Fate In Environmental Systems, Haesung Jung

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese (hydr)oxide (Mn (hydr)oxide) minerals are ubiquitous in aquatic and terrestrial environments. These minerals have high surface areas and are highly sorptive and redox active. From decades of accumulated knowledge about natural redox cycling, we have found that Mn (hydr)oxides play critical roles as electron donors and acceptors in elemental geochemical cycling and biological metabolisms in nature. Thus, Mn (hydr)oxides have garnered increasing interest to understand natural systems. Considering the variety of redox reactions with Mn (hydr)oxides in nature, it is also expected that there should be diverse pathways to form Mn (hydr)oxides through abiotic and biotic processes. Previous studies …


Phosphate Speleothems In Caves Developed In Iron Ores And Laterites Of The Carajás Mineral Province (Brazil) And A New Occurrence Of Spheniscidite, Alan R.L. Albuquerque, Rômulo S. Angélica, Daniele F. Gonçalves, Simone P.A. Paz 2017 Universidade Federal do Pará

Phosphate Speleothems In Caves Developed In Iron Ores And Laterites Of The Carajás Mineral Province (Brazil) And A New Occurrence Of Spheniscidite, Alan R.L. Albuquerque, Rômulo S. Angélica, Daniele F. Gonçalves, Simone P.A. Paz

International Journal of Speleology

The Carajás Mineral Province has one of the largest concentrations of caves in Brazil, and its iron ore is among the country’s main exports. As a result of iron ore intense extraction, new environmental policies have been implemented. In an attempt to balance economic activity and environmental conservation, an inventory and a relevance-based classification of caves were implemented in 2008 as criteria for environmental licensing of mining ventures. This implementation motivated the present study of phosphate speleothems in Carajás’ caves developed in ferriferous rocks. The objectives of this study are to describe the phosphate minerals and their formation processes based …


Provenance Analysis Of The Grover Gravel Using Detrital Zircon Geochronology, Petrology And Heavy Mineral Analysis, Grant Spoering 2017 Missouri State University

Provenance Analysis Of The Grover Gravel Using Detrital Zircon Geochronology, Petrology And Heavy Mineral Analysis, Grant Spoering

Graduate Theses/Dissertations

The Grover Gravel in the St. Louis, Missouri area contains a mix of chert, quartzite, jasper, and ironstone in clast sizes ranging up to 60 cm. The gravel varies in thickness from a veneer to over 30 feet and rests on upland surfaces at elevations sometimes exceeding 300 feet above the floors of major valleys. A pre-Pleistocene age generally has been proposed or assumed for the gravel, which classically has been interpreted to be a meandering-stream deposit atop an extensive flat upland surface, which was subsequently eroded and dissected by rejuvenated streams. However, large quartzite boulders in the gravel also …


Geophysical Delineation Of Megaporosity And Fluid Migration Pathways For Geohazard Characterization Within The Delaware Basin, Culberson County, Texas, Jonathan David Woodard 2017 Stephen F. Austin State University

Geophysical Delineation Of Megaporosity And Fluid Migration Pathways For Geohazard Characterization Within The Delaware Basin, Culberson County, Texas, Jonathan David Woodard

Electronic Theses and Dissertations

ABSTRACT

Differential dissolution of gypsum karst within the Delaware Basin poses a significant threat to infrastructure that society depends on. The study area is located in Culberson County, Texas and traverses a distance of approximately 54 kilometers along RM 652 within the Gypsum Plain which is situated on the northern margin of the Chihuahua Desert and includes outcrops of Castile and Rustler strata that host karst geohazards. Regions of karst geohazard potential have been physically surveyed proximal to the study area in evaporites throughout the Castile Formation outcrop; minimal hazards, in comparison to the Castile Formation, have been documented in …


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 …


Cave Monitoring In The Béke And Baradla Caves (Northeastern Hungary): Implications For The Conditions For The Formation Cave Carbonates, György Czuppon, Attila Demény, Szabolcs Leél-Őssy, Mihály Óvari, Mihály Molnár, József Stieber, Klaudia Kiss, Krisztina Kármán, Gergely Surányi, László Haszpra 2017 Institute for Geological and Geochemical Research, RCAES, Hungarian Academy of Sciences

Cave Monitoring In The Béke And Baradla Caves (Northeastern Hungary): Implications For The Conditions For The Formation Cave Carbonates, György Czuppon, Attila Demény, Szabolcs Leél-Őssy, Mihály Óvari, Mihály Molnár, József Stieber, Klaudia Kiss, Krisztina Kármán, Gergely Surányi, László Haszpra

International Journal of Speleology

In order to use speleothems in the reconstruction of past climate and environmental changes it is necessary to understand the environmental and hydrological processes that determine the physico-chemical conditions of carbonate precipitation and hence speleothem formation. Therefore, in this study an extended monitoring program was conducted in the Béke and Baradla caves located in the Aggtelek region (Northeastern Hungary). The studied caves are rich in speleothem and flowstone occurrences with great potential for paleoclimatology studies. The monitoring activity included measurements of atmospheric and cave temperatures, CO2 concentration in cave air, as well as chemical and isotopic compositions of water …


U–Pb Dating Of Cave Spar: A New Shallow Crust Landscape Evolution Tool, D. D. Decker, V. J. Ployak, Y. Asmeron, Matthew Lachniet 2017 University of New Mexico

U–Pb Dating Of Cave Spar: A New Shallow Crust Landscape Evolution Tool, D. D. Decker, V. J. Ployak, Y. Asmeron, Matthew Lachniet

Geoscience Faculty Research

In carbonate terranes, rocks types that provide apatite are not available to effectively use apatite fission track (AFT) or (U/Th)‐He chronometry (AHe). Here we suggest that calcite cave spar can be an effective chronometer and complimentary to AFT and AHe thermochronometers in carbonate regions such as our study area, the Guadalupe Mountains of southeastern New Mexico, and west Texas. Our measured depth of cave spar deposition is 500 ± 250 m beneath the regional water table, formed at temperatures of 40° to 80°C, indicating that these caves and their spar crystals form near the supercritical CO2‐subcritical CO2 boundary where we …


Resolving Chronological And Temperature Constraints On Antarctic Deglacial Evolution Through Improved Dating Methodology, Cristina Subt 2017 University of South Florida

Resolving Chronological And Temperature Constraints On Antarctic Deglacial Evolution Through Improved Dating Methodology, Cristina Subt

USF Tampa Graduate Theses and Dissertations

In order to determine the timing of Antarctic ice sheet retreat and advance during the Late Quaternary, various tools are used to measure the age of marginal marine sediments. Carbonate 14C dating is a well-established approach, but requires foraminiferal microfossils, shells or other carbonate materials that are rare in most Antarctic regions, and may also suffer from vital effects, which can result in variability of up to 500 years in living organisms. Bulk acid insoluble organic (AIO) 14C dates are frequently as an alternative, but this approach works best where high productivity and sedimentation rates reign, and not too well …


Paleoenvironmental Reconstruction Using Coral Microatolls (Sp. Siderastrea Siderea) From The Gulf Of Gonâve, Haiti, Gilman Reno Ouellette Jr. 2017 Louisiana State University and Agricultural and Mechanical College

Paleoenvironmental Reconstruction Using Coral Microatolls (Sp. Siderastrea Siderea) From The Gulf Of Gonâve, Haiti, Gilman Reno Ouellette Jr.

LSU Doctoral Dissertations

Natural and anthropogenic climate changes present unique and serious risks to society. In order to plan and implement adaptation and mitigation strategies successfully, regional manifestations of broad-scale climate changes must be understood robustly. The Caribbean region contains part of the Western Hemisphere Warm Pool (WHWP), a major sea surface temperature (SST) feature that plays a key role in North Atlantic climate. Climate variability in the Caribbean is captured poorly by climate models, due in part to a lack of continuous, multidecadal instrumental climate records from the region. I explored three research questions in this dissertation: Does non-systematic bias exist in …


Paleoenvironmental Variation And Provenance Records From Neogene Deep Sea Sediment Of The South China Sea, Chang Liu 2017 Louisiana State University and Agricultural and Mechanical College

Paleoenvironmental Variation And Provenance Records From Neogene Deep Sea Sediment Of The South China Sea, Chang Liu

LSU Doctoral Dissertations

I employed several paleoenvironmental proxies by utilizing deep sea sediment from the largest marginal basin in east Asia, namely the South China Sea (SCS), to reconstruct the long term paleoenvironmental variation in SE Asia since the Neogene. Sediments deposited within the SCS were mainly delivered by several major fluvial systems whose catchment basins cover several geological blocks in SE Asia. By analyzing the sediment’s geochemical and mineralogical characteristics, several indices which are affected by the source of the sedimentary influx, as well as the weathering state could be built and applied to constrain my paleoenvironmental reconstructions

Two deep sea drilling …


Digital Commons powered by bepress