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Articles 5161 - 5190 of 29938

Full-Text Articles in Geology

Mgrre_Thinsections_Mgrre-04_9, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_9, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_10, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_10, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_16, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_16, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_17, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_17, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_18, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_18, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_19, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_19, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_20, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_20, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-02_3, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-02_3, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-02_11, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-02_11, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-02_20, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-02_20, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-02_15, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-02_15, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-04_15, Mgrre Oct 2022

Mgrre_Thinsections_Mgrre-04_15, Mgrre

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No abstract provided.


Hydrogen Isotope Behavior During Rhyolite Glass Hydration Under Hydrothermal Conditions, Michael R. Hudak, Ilya N. Bindeman, James M. Watkins, Jacob B. Lowenstern Oct 2022

Hydrogen Isotope Behavior During Rhyolite Glass Hydration Under Hydrothermal Conditions, Michael R. Hudak, Ilya N. Bindeman, James M. Watkins, Jacob B. Lowenstern

United States Geological Survey: Staff Publications

The diffusion of molecular water (H2Om) from the environment into volcanic glass can hydrate the glass up to several wt% at low temperature over long timescales. During this process, the water imprints its hydrogen isotope composition (δDH2O) to the glass (δDgl) offset by a glass-H2O fractionation factor (ΔDgl-H2O = δDgl – δDH2O) which is approximately -33‰ at Earth surface temperatures. Glasses hydrate much more rapidly at higher, sub-magmatic temperatures as they interact with H2O during eruption, transport, and emplacement. To aid in the interpretation …


Evaluating Our Reliance On Rare Earth Minerals And Platinum Group Metals Over The Period Of 2012 To 2021, Ryan Smith Oct 2022

Evaluating Our Reliance On Rare Earth Minerals And Platinum Group Metals Over The Period Of 2012 To 2021, Ryan Smith

Fall Showcase for Research and Creative Inquiry

Rare Earth Elements (REE’s) are minerals used in our everyday lives. They can be found in our household appliances, phones, computers, cars, as part of wind turbines and solar panels. The US relies on imports of these rare earths from several other countries (e.g. China, Estonia, Malaysia, and Japan) as we cannot mine a majority of the minerals (e.g. cerium, lanthanum, europium, etc) domestically. Since the year 2012, the US has imported approximately 3,000 metric tons of rare earths, and in recent years, this number significantly increased. As of 2021, the US now imports approximately 43,000 metric tons of rare …


Mgrre_Thinsections_05_A_37, Mgrre Oct 2022

Mgrre_Thinsections_05_A_37, Mgrre

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No abstract provided.


Intact Polar Brgdgts In Arctic Lake Catchments: Implications For Lipid Sources And Paleoclimate Applications, Jonathan H. Raberg, Edgart Flores, Sarah E. Crump, Greg De Wet, Nadia Dildar, Gifford H. Miller, Áslaug Geirsdóttir, Julio Sepúlveda Oct 2022

Intact Polar Brgdgts In Arctic Lake Catchments: Implications For Lipid Sources And Paleoclimate Applications, Jonathan H. Raberg, Edgart Flores, Sarah E. Crump, Greg De Wet, Nadia Dildar, Gifford H. Miller, Áslaug Geirsdóttir, Julio Sepúlveda

Geosciences: Faculty Publications

Paleotemperature histories derived from lake sediment archives provide valuable context for modern and future climate changes. Branched glycerol dialkyl glycerol tetraether (brGDGT) lipids are a valuable tool in such pursuits due to their empirical correlation with temperature and near ubiquity in nature. However, the relative contributions of terrestrial and lacustrine sources of brGDGTs to lake sediments is site-dependent and difficult to constrain. Here, we explored the potential for intact brGDGTs—the complete lipids with polar head groups (HGs) still attached—to provide insight into the sources of brGDGTs on the landscape and their contributions to the sedimentary record in a set of …


Sulfur Behavior In The 1257 Ce Samalas Magma (Lombok, Indonesia) As Revealed By Volcanic Apatite, Yasmin Jackson Oct 2022

Sulfur Behavior In The 1257 Ce Samalas Magma (Lombok, Indonesia) As Revealed By Volcanic Apatite, Yasmin Jackson

Earth Sciences Theses and Dissertations

Explosive volcanic eruptions can inject massive amounts of volatiles, including SO2 and H2S, into the stratosphere, inducing drastic tropospheric cooling via sulfate aerosols. Greenland and Antarctic ice cores record evidence of these substantial releases of SO2 and H2S, including the massive release during the ultraplinian 1257 CE Samalas eruption. The 1257 CE Samalas eruption is estimated to have released ~158 Tg of SO2, making it the largest volcanogenic release of SO2 within the last 2000 years. Vidal et al. (2016) propose that most of this sulfur (S) was hosted in a …


Soils Of The Central Nebraska Loess Hills And Central Loess Plains, Judith Turk, Rebecca Young, Nicolas A. Jelinsky, Amber D. Anderson, Ashlee Dere, Colby J. Moorberg, Rachel K. Owen Oct 2022

Soils Of The Central Nebraska Loess Hills And Central Loess Plains, Judith Turk, Rebecca Young, Nicolas A. Jelinsky, Amber D. Anderson, Ashlee Dere, Colby J. Moorberg, Rachel K. Owen

Conservation and Survey Division: Faculty and Staff Publications

Understanding soil systems that characterize a region is critical to natural resource management. However, the knowledge gained through intensive study of local soil systems, which takes place annually as part of collegiate soil judging contests, is often poorly preserved for future use. In this study, field descriptions and laboratory data for 16 soil profiles described for the 2019 Region 5 Soil Judging Contest were used to characterize the soil system of the Central Nebraska Loess Hills and Central Loess Plains. Three landscape components of this soil system were analyzed: the loess uplands and rainwater basins, the transitional zone, and bottomlands. …


Mgrre_Thinsections_05_A_36, Mgrre Sep 2022

Mgrre_Thinsections_05_A_36, Mgrre

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No abstract provided.


Effects Of Small-Scale Mining Activities On Fisheries And Livelihoods In The Birim River In Atiwa District, Eastern Region Of Ghana, Elliot Haruna Alhassan, Samuel Opoku Dandi, Sandra Akugpoka Atindana Sep 2022

Effects Of Small-Scale Mining Activities On Fisheries And Livelihoods In The Birim River In Atiwa District, Eastern Region Of Ghana, Elliot Haruna Alhassan, Samuel Opoku Dandi, Sandra Akugpoka Atindana

Tanzania Journal of Science

The socioeconomic importance of small-scale mining in Ghana is of great interest to the country. It provides employment, supports the livelihood of poor rural areas, and also contributes to national income. Despite all these importance, it has a great influence on the surroundings, with surface and groundwater bodies being the most affected. The study was conducted to determine the effects of small-scale mining activities on fisheries and livelihoods along the Birim River in Atiwa District of Ghana, and also, to ascertain the nature of mining in the catchment and the current status of fisheries in the river. Data were collected …


Evaluation Of Enzymatic Activity During Growth Of Pleurotus Hk 37 On Saba Comorensis Exocarp, Isse I. Molobele, Rose J. Masalu, Prosper R. Mosha, Cyprian B. Mpinda Sep 2022

Evaluation Of Enzymatic Activity During Growth Of Pleurotus Hk 37 On Saba Comorensis Exocarp, Isse I. Molobele, Rose J. Masalu, Prosper R. Mosha, Cyprian B. Mpinda

Tanzania Journal of Science

Mushrooms degrade lignocellulosic biomass by releasing lignolytic and hydrolytic enzymes which convert lignocellulosic material into soluble and low molecular weight compounds which are then absorbed as nutrients. In the present study, enzymatic activities of Pleurotus HK 37 during growth on Saba comorensis exocarps were evaluated. It was observed that, Pleurotus HK 37 has ability to produce lignolytic enzyme (Laccase) and hydrolytic enzymes (Carboxymethyl cellulase, xylanase and filterpaperase). Maximum laccase activity of 3.33 ± 0 UmL-1 was observed during colonization period and the activity dropped during fruitification phase. Similar to hydrolytic enzymes, the activity was observed during colonization period and decreased …


Drivers Of Pb, Sb And As Release From Spent Gunshot In Wetlands: Enhancement By Organic Matter And Native Microorganisms, Anna Potysz, Łukasz J. Binkowski, Jakub Kierczak, Barnett A. Rattner Sep 2022

Drivers Of Pb, Sb And As Release From Spent Gunshot In Wetlands: Enhancement By Organic Matter And Native Microorganisms, Anna Potysz, Łukasz J. Binkowski, Jakub Kierczak, Barnett A. Rattner

United States Geological Survey: Staff Publications

In many countries the use of lead-based ammunition is prevalent, and results in exposure and poisoning of waterfowl and other species of birds. In waterfowl hunting areas large quantities of spent shot may be deposited in wetland and terrestrial habitats. These pellets can undergo transformations, which are influenced by various abiotic and biotic factors. In addition to lead (Pb), other elements like antimony (Sb) and arsenic (As) can be leached from Pb shot into the environment. In vitro simulations that included organic matter and microorganisms were utilized to examine elemental leaching from gunshot. We found that leaching efficiency was the …


Mgrre_Thinsections_05_A_35, Mgrre Sep 2022

Mgrre_Thinsections_05_A_35, Mgrre

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No abstract provided.


Limits To Coseismic Landslides Triggered By Cascadia Subduction Zone Earthquakes, Alex R.R. Grant, William T. Struble, Sean R. Lahusen Sep 2022

Limits To Coseismic Landslides Triggered By Cascadia Subduction Zone Earthquakes, Alex R.R. Grant, William T. Struble, Sean R. Lahusen

United States Geological Survey: Staff Publications

Landslides are a significant hazard and dominant feature throughout the landscape of the Pacific Northwest. However, the hazard and risk posed by coseismic landslides triggered by great Cascadia Subduction Zone (CSZ) earthquakes is highly uncertain due to a lack of local and global data. Despite a wealth of other geologic evidence for past earthquakes on the Cascadia Subduction Zone, no landslides have been definitively linked to such earthquakes, even in areas otherwise highly susceptible to failure. While shallow landslides may not leave a lasting topographical signature in the landscape, there are thousands of deep-seated landslides in Cascadia, and these deposits …


Mgrre_Thinsections_05_A_34, Mgrre Sep 2022

Mgrre_Thinsections_05_A_34, Mgrre

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No abstract provided.


Very High Middle Miocene Surface Productivity On The U.S. Mid-Atlantic Shelf Amid Glacioeustatic Sea Level Variability, Marci M. Robinson, Harry J. Dowsett, Timothy D. Herbert Sep 2022

Very High Middle Miocene Surface Productivity On The U.S. Mid-Atlantic Shelf Amid Glacioeustatic Sea Level Variability, Marci M. Robinson, Harry J. Dowsett, Timothy D. Herbert

United States Geological Survey: Staff Publications

The Miocene Climatic Optimum (MCO) provides important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. Few western North Atlantic paleotemperature or paleoecological records exist from the MCO, despite their importance for understanding both regional and global climate dynamics. Here we present quantitative MCO paleoecological data from the western North Atlantic, specifically from the Baltimore Gas & Electric (BG&E) marine sediment core from southern Maryland, USA. We examine alkenones and planktic foraminifera and document the first sea surface temperature (SST) and productivity estimates for the MCO and the Middle Miocene Climate Transition (MMCT) from …


Discovering Hidden Geothermal Signatures Using Non-Negative Matrix Factorization With Customized K-Means Clustering, V. V. Vesselinov, B. Ahmmed, M. K. Mudunuru, J. D. Pepin, E. R. Burns, D. L. Siler, S. Karra, R. S. Middleton Sep 2022

Discovering Hidden Geothermal Signatures Using Non-Negative Matrix Factorization With Customized K-Means Clustering, V. V. Vesselinov, B. Ahmmed, M. K. Mudunuru, J. D. Pepin, E. R. Burns, D. L. Siler, S. Karra, R. S. Middleton

United States Geological Survey: Staff Publications

Discovery of hidden geothermal resources is challenging. It requires the mining of large datasets with diverse data attributes representing subsurface hydrogeological and geothermal conditions. The commonly used play fairway analysis approach typically incorporates subject-matter expertise to analyze regional data to estimate geothermal characteristics and favorability. We demonstrate an alternative approach based on machine learning (ML) to process a geothermal dataset from southwest New Mexico (SWNM). The study region includes low- and medium-temperature hydrothermal systems. Several of these systems are not well characterized because of insufficient existing data and limited past explorative work. This study discovers hidden patterns and relations in …


Neural Net Detection Of Seismic Features Related To Gas Hydrates And Free Gas Accumulations On The Northern U.S. Atlantic Margin, Urmi Majumdar, Nathaniel C. Miller, Carolyn D. Ruppel Sep 2022

Neural Net Detection Of Seismic Features Related To Gas Hydrates And Free Gas Accumulations On The Northern U.S. Atlantic Margin, Urmi Majumdar, Nathaniel C. Miller, Carolyn D. Ruppel

United States Geological Survey: Staff Publications

Bottom-simulating reflections (BSRs) that sometimes mark the base of the gas hydrate stability zone in marine sediments are often identified based on the reverse polarity reflections that cut across stratigraphic layering in seismic amplitude data. On the northern U.S. Atlantic margin (USAM) between Cape Hatteras and Hudson Canyon, legacy seismic data have revealed pronounced BSRs south of the deepwater extension of Hudson Canyon and more subtle ones from offshore Delaware south to Cape Hatteras, where the reflections sometimes follow stratigraphic layering. Using high-resolution seismic data acquired during the 2018 Mid-Atlantic Resource Imaging Experiment and a supervised neural net, we identify …


Mgrre_Thinsections_05_A_33, Mgrre Sep 2022

Mgrre_Thinsections_05_A_33, Mgrre

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No abstract provided.


Establishment Of Invasive Black Carp (Mylopharyngodon Piceus) In The Mississippi River Basin: Identifying Sources And Year Classes Contributing To Recruitment, Gregory W. Whitledge, Patrick T. Kroboth, Duane C. Chapman, Quinton E. Phelps, Wes Sleeper, Jennifer Bailey, Jill A. Jenkins Sep 2022

Establishment Of Invasive Black Carp (Mylopharyngodon Piceus) In The Mississippi River Basin: Identifying Sources And Year Classes Contributing To Recruitment, Gregory W. Whitledge, Patrick T. Kroboth, Duane C. Chapman, Quinton E. Phelps, Wes Sleeper, Jennifer Bailey, Jill A. Jenkins

United States Geological Survey: Staff Publications

Black Carp (Mylopharyngodon piceus) was imported to the USA to control aquaculture pond snails. This species has escaped captivity and occurs in parts of the Mississippi River, several tributaries, and floodplain lakes, which is concerning due to potential competition with native fishes and predation on native mussels, many of which are imperiled. However, Black Carp captures have primarily been incidental by commercial fishers, and evidence of reproduction in the wild is limited. The objectives of this study were to assess relative abundance of aquaculture- origin and wild Black Carp using ploidy and otolith stable isotope analysis, identify spatial …