Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Environmental Sciences (33)
- Geophysics and Seismology (18)
- Oceanography and Atmospheric Sciences and Meteorology (15)
- Geochemistry (13)
- Other Earth Sciences (13)
-
- Geomorphology (11)
- Other Environmental Sciences (11)
- Hydrology (10)
- Social and Behavioral Sciences (10)
- Geography (9)
- Paleontology (9)
- Life Sciences (8)
- Soil Science (8)
- Natural Resources and Conservation (7)
- Physical and Environmental Geography (7)
- Tectonics and Structure (7)
- Sedimentology (6)
- Stratigraphy (6)
- Glaciology (5)
- Natural Resource Economics (5)
- Oil, Gas, and Energy (5)
- Environmental Indicators and Impact Assessment (4)
- Environmental Monitoring (4)
- Natural Resources Management and Policy (4)
- Biology (3)
- Engineering (3)
- Environmental Health and Protection (3)
- Institution
-
- University of Nebraska - Lincoln (19)
- University of Kentucky (15)
- Central Washington University (13)
- Utah State University (12)
- Missouri University of Science and Technology (10)
-
- University of Texas at El Paso (8)
- Western Kentucky University (8)
- University of Nevada, Las Vegas (7)
- Brigham Young University (6)
- University of North Dakota (6)
- Smith College (5)
- University at Albany, State University of New York (4)
- University of South Florida (4)
- Old Dominion University (3)
- Stephen F. Austin State University (3)
- Boise State University (2)
- Gettysburg College (2)
- Louisiana State University (2)
- Portland State University (2)
- University of Dar es Salaam (2)
- University of Dayton (2)
- University of Montana (2)
- Andrews University (1)
- California Polytechnic State University, San Luis Obispo (1)
- Department of Primary Industries and Regional Development, Western Australia (1)
- Grand Valley State University (1)
- Illinois State University (1)
- Michigan Technological University (1)
- Montana Tech Library (1)
- Nova Southeastern University (1)
- Keyword
-
- Geology (7)
- Groundwater (6)
- Geophysics (5)
- Seismology (5)
- Carbon sequestration (4)
-
- GPS (4)
- Hydrology (4)
- Geological carbon sequestration (3)
- Holocene (3)
- Hydrogeology (3)
- Karst (3)
- Mining (3)
- Quartz (3)
- Antarctica (2)
- Arroyo (2)
- Biofilm (2)
- Caves (2)
- China (2)
- Conservation and Survey Division (2)
- Contamination (2)
- Drift ice (2)
- Environmental contaminants (2)
- Faults (2)
- Forward Modeling (2)
- Geochemistry (2)
- Geographic Information System (2)
- History (2)
- Hypogene karst (2)
- Ice rafted debris (2)
- Ice stream (2)
- Publication
-
- United States Geological Survey: Staff Publications (10)
- Map and Chart--KGS (9)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (8)
- Open Access Theses & Dissertations (8)
- All Faculty Scholarship for the College of the Sciences (7)
-
- Theses and Dissertations (7)
- UNLV Theses, Dissertations, Professional Papers, and Capstones (7)
- Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works (5)
- Geosciences: Faculty Publications (5)
- University of Kentucky Master's Theses (5)
- Conservation and Survey Division: Faculty and Staff Publications (4)
- Earth, Environmental, and Atmospheric Sciences Faculty Publications (4)
- Doctoral Dissertations (3)
- EERC Brochures and Fact Sheets (3)
- Faculty Scholarship for the Cascadia Hazards Institute (3)
- Geology Faculty Publications (3)
- Geology Theses and Dissertations (3)
- Geosciences Faculty Publications (3)
- OES Faculty Publications (3)
- All Graduate Plan B and other Reports, Spring 1920 to Spring 2023 (2)
- Boise State University Theses and Dissertations (2)
- Department of Earth, Environment and Sustainability Faculty Publications (2)
- Environmental Studies Faculty Publications (2)
- Faculty Presentations (2)
- Faculty Publications (2)
- Geology Faculty Publications and Presentations (2)
- Honors Capstones (2)
- Masters Theses (2)
- Masters Theses & Specialist Projects (2)
- Tanzania Journal of Science (2)
- Publication Type
- File Type
Articles 31 - 60 of 148
Full-Text Articles in Geology
Internal Structure And Geochronology Of The Gerrei Unit In The Flumendosa Area, Variscan External Nappe Zone, Sardinia, Italy, Ashley V. Dack
Internal Structure And Geochronology Of The Gerrei Unit In The Flumendosa Area, Variscan External Nappe Zone, Sardinia, Italy, Ashley V. Dack
Boise State University Theses and Dissertations
To investigate the stratigraphy and structural evolution of the Variscan Orogen of the External Nappe Zone, Sardinia, Italy, field work and geochronologic analyses were combined to assess both regional and orogen scale issues. Geologic mapping, structural analysis, and sampling in the Flumendosa area coupled with high-precision U-Pb zircon geochronology were used to determine the duration of Ordovician magmatic activity and the structural evolution of the Variscan Orogen.
To constrain the duration of magmatism for the Flumendosa area, U-Pb ID/TIMS zircon analyses were performed on samples from a lower volcanic flow of the Ordovician Volcanic Unit and an upper, syn to …
Paragneiss Zircon Geochronology And Trace Element Geochemistry, North Qaidam Hp/Uhp Terrane, Western China, Chris G. Mattinson, Joseph L. Wooden, Jian-Xin Zhang, D. K. Bird
Paragneiss Zircon Geochronology And Trace Element Geochemistry, North Qaidam Hp/Uhp Terrane, Western China, Chris G. Mattinson, Joseph L. Wooden, Jian-Xin Zhang, D. K. Bird
All Faculty Scholarship for the College of the Sciences
In the southeastern part of the North Qaidam terrane, near Dulan, paragneiss hosts minor peridotite and UHP eclogite. Zircon geochronology and trace element geochemistry of three paragneiss samples (located within a ∼3 km transect) indicates that eclogite-facies metamorphism resulted in variable degrees of zircon growth and recrystallization in the three samples. Inherited zircon core age groups at 1.8 and 2.5 Ga suggest that the protoliths of these rocks may have received sediments from the Yangtze or North China cratons. Mineral inclusions, depletion in HREE, and absence of negative Eu anomalies indicate that zircon U-Pb ages of 431 ± 5 Ma …
Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley
Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley
All Faculty Scholarship for the College of the Sciences
New seismic observations of harmonic tremors beneath MacAyeal Ice Stream, West Antarctica are reported. Each of the two tremor events that we recorded during a six week period had sustained arrival of 3 Hz energy for approximately 10 minutes. During that time the source location migrated a few kilometers. The harmonic nature of the tremors is interpreted as the result of resonance in subglacial water-filled cracks and conduits. The duration, monochromatic nature, and movement of the tremor indicate that the source mechanism is likely flow in the subglacial water system resulting from the discharge from a small subglacial lake. Our …
What Is Ccs?, University Of North Dakota. Energy And Environmental Research Center
What Is Ccs?, University Of North Dakota. Energy And Environmental Research Center
EERC Brochures and Fact Sheets
Fact sheet about carbon capture and storage (CCS) and the Plains CO2 Reduction (PCOR) Partnership. Outlines the three phases of U.S. Department of Energy National Energy Technology Laboratory’s Regional Carbon Sequestration Partnership program. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]
Tree Ring Dating Of Logs From Tschantz Cabin, Kidron, Oh
Tree Ring Dating Of Logs From Tschantz Cabin, Kidron, Oh
Historic Structures
Dating historical structures in Wayne County, Ohio using dendrochronology. The Historical Structures collection consists of reports that are the result of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Aughenbaugh, Kelly; Mennett, Colin; Wiesenberg, Nicholas; Wiles, Greg
Tailings Tale: Mike Horse Looms Dark Over The Blackfoot, Elizabeth L. Harrison
Tailings Tale: Mike Horse Looms Dark Over The Blackfoot, Elizabeth L. Harrison
Graduate Student Portfolios, Professional Papers, and Capstone Projects
In the spring of 1975, a heavy rain blew out an earthen dam holding back toxic metal waste from the now defunct Mike Horse mine at the headwaters of the scenic Big Blackfoot River. Federal agencies, a corporate mining giant, and the small town community of Lincoln, Montana, grapple with the repercussions and future of the watershed.
Vadose Zone Hydrology Near The Vicinity Of Edna's Dome, Mammoth Cave, Kentucky, Johnny Merideth
Vadose Zone Hydrology Near The Vicinity Of Edna's Dome, Mammoth Cave, Kentucky, Johnny Merideth
Masters Theses & Specialist Projects
This study examines the differences in key physical aqueous parameters at two different cave sites separated by only a few tens of meters. One site (FF) has a freefalling water component where water descends nearly 30 meters from the ceiling of a vertical shaft. The other location (WW) appears to have continuous water to rock contact as it descends to near the same level in the cave.
Water samples were collected at the two sites in two week intervals from May to August 2002. While both sites were proximal, they demonstrated very different behaviors, particularly during storm events. Differences in …
Biogeochemical Behavior Of Dissolved Arsenic And Uranium Concentrations In Public Water Supply Wells, Kevin J. Mcvey
Biogeochemical Behavior Of Dissolved Arsenic And Uranium Concentrations In Public Water Supply Wells, Kevin J. Mcvey
School of Natural Resources: Dissertations, Theses, and Student Research
Public water supply (PWS) wells currently contain dissolved uranium concentrations above the federally mandated maximum contaminant level (MCL) of 30 ppb (parts per billion) and dissolved arsenic concentrations above the 10 ppb MCL. Both uranium and arsenic are known to cause various forms of cancer in humans. Variations in total uranium concentrations in PWS wells in Nebraska indicate a relationship to the duration and rate of pumping in specific wells. Although total arsenic concentrations show some variability over time in specific wells, the relationship to pumping is not as clear. Previous studies show that iron and sulfur bacteria present in …
Performance Of Upham Beach T-Groin Project And Its Impact To The Downdrift Beach, Ping Wang, Tiffany M. Roberts
Performance Of Upham Beach T-Groin Project And Its Impact To The Downdrift Beach, Ping Wang, Tiffany M. Roberts
Geology Faculty Publications
The field of 5 T-groins installed at Upham Beach was designed to maintain a portion of the nourished beach at this chronically eroding location without negative impacts to the downdrift beach. The T-groin project area was renourished in September 2006 and all the structures were buried. During the initial 3 months after the nourishment, rapid beach erosion at the north segment, as typical of Upham Beach, was measured. Since all the structures were buried, this rapid erosion should not be directly related to the T-groin field. The downdrift beach remained largely stable to slightly accretionary, benefiting from the sand supply …
Investigations Into Mapping Lava Flows In The Snake River Plain, Idaho, Vinita Ruth Hobson-Broko
Investigations Into Mapping Lava Flows In The Snake River Plain, Idaho, Vinita Ruth Hobson-Broko
All Graduate Plan B and other Reports, Spring 1920 to Spring 2023
The origin of the Snake River plain continues to be debated, but the plume model is most popular at the current time. Some theories, such as meteorite impact, have been excluded, but the remaining theories require more scrutiny.
Various methods of examining phenomena in the Snake River Plain were employed. Unsupervised classification of Landsat ETM data indicates that spectra can be used to differentiate between flows. However, photographs of flows at Craters of the Moon National Monument show wide variations in texture and color within a single flow. Vegetation grows preferentially on the smoother pahoehoe slabs and significantly impacting the …
Using Real-World Data As A Basis For Problem-Based Learning: Investigating Preservation Biases Of Fish In Fossil Butte National Monument, Blair Larsen
All Graduate Plan B and other Reports, Spring 1920 to Spring 2023
This project examined the design and development of an online problem-based learning module to teach earth-system science to K-12 educators. The module revolved around identifying earth sphere (lithosphere, hydrosphere, biosphere and atmosphere) interactions needed to produce mass fish mortality layers found in the Green River Formation at Fossil Butte National Monument. Students investigated the unique earth sphere combinations needed to produce mass fish mortality layers, reflected on the formation of such deposits, and examined the impact of these earth spheres on the earth system. As a supplement to the course, the students also analyzed data on fossils collected from a …
The Sheep Pass Formation, A Record Of Late Cretaceous And Paleogene Extension Within The Sevier Hinterland, East-Central Nevada, Peter Alexander Druschke
The Sheep Pass Formation, A Record Of Late Cretaceous And Paleogene Extension Within The Sevier Hinterland, East-Central Nevada, Peter Alexander Druschke
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Sevier hinterland of western North America is considered by many to be an ancient proxy for the modern Andean Puna-Altiplano or Tibetan Plateau. However, controversies exist as tectonic setting and overall paleogeography of the Sevier hinterland during the Late Cretaceous and Paleogene. The Sheep Pass Formation type section within the southern Egan Range of east-central Nevada comprises a > 1 km thick sedimentary succession spanning the latest Cretaceous to Eocene, and provides a rare opportunity to test prevailing tectonic and paleogeographic models for the Sevier hinterland. New 1:12,000 scale field mapping inthe southern Egan Range indicates that up to three …
A River Transformed: Historic Geomorphic Changes Of The Lower Rio Grande In The Big Bend Region Of Texas, Chihuahua, And Coahuila, David James Dean
A River Transformed: Historic Geomorphic Changes Of The Lower Rio Grande In The Big Bend Region Of Texas, Chihuahua, And Coahuila, David James Dean
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Over the last century, the construction and management of large dams and stream-flow diversions, and periodic drought have resulted in significant declines in stream flow of the lower Rio Grande in the Big Bend region. Reductions in mean annual flow and peak discharge have resulted in channel narrowing by the formation of vertically accreting inset floodplains. Narrowing has been temporarily interrupted by infrequent large dam releases greater than 1000 m3/s that have temporarily widened the channel; however, after each of these events, narrowing has resumed. Prior to 1942, floods of this magnitude occurred approximately once every 4 years …
A Geologic And Hydrochemical Investigation Of The Suitability Of Central Utah's Navajo Sandstone For The Disposal Of Saline Process Water And Co2, Kevin L. Randall
A Geologic And Hydrochemical Investigation Of The Suitability Of Central Utah's Navajo Sandstone For The Disposal Of Saline Process Water And Co2, Kevin L. Randall
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Salt water is produced from the Ferron Sandstone Member of the Mancos Shale in central Utah as part of the production of coalbed methane (CBM) and is disposed of by injection predominantly into the Navajo Sandstone between 4,500 feet to 7,300 feet and is considered to be a hazardous waste. Local government agencies are concerned about the potential impacts on shallow groundwater because of this disposal method.
Water samples were gathered from four shallow water-supply wells, and nine salt water disposal (SWD) wells to compare hydrochemistries as an indicator of potential mixing. Shallow water-supply wells are likely recharged by local …
Eastern Mediterranean Pore Waters: Clues Into The Geochemical Pathways From Evaporated Seawater To Basinal Brines, Jessica A. Mumphrey
Eastern Mediterranean Pore Waters: Clues Into The Geochemical Pathways From Evaporated Seawater To Basinal Brines, Jessica A. Mumphrey
Honors Capstones
No abstract provided.
Correlation, Paleogeography, And Provenance Of The Neoproterozoic Eastern Uinta Mountain Group, Goslin Mountain Area, Northeastern Utah, Daniel J. Rybczynski
Correlation, Paleogeography, And Provenance Of The Neoproterozoic Eastern Uinta Mountain Group, Goslin Mountain Area, Northeastern Utah, Daniel J. Rybczynski
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Geologic mapping, facies analysis, sedimentary petrography, and detrital zircon analyses of undivided eastern Uinta Mountain Group stratigraphy are presented to better understand the depositional environments and tectonic setting of the Uinta Mountain Group basin. Subdivided units have been modified and correlated from previous work and include the Red Pine Shale, Hades Pass, Crouse Canyon, Outlaw Trail, and Diamond Breaks formations. Three lower-order maximum flooding surfaces associated with the lower Outlaw Trail formation, lower Hades Pass formation, and Red Pine Shale are interpreted. The relative magnitude of each lower-order transgression increases up section along with increasing diversity of palynomorph assemblages found …
Evolution Of The Lower Cretaceous Chifeng Half-Graben Basins, Inner Mongolia, China, Scott Joshua Friedman
Evolution Of The Lower Cretaceous Chifeng Half-Graben Basins, Inner Mongolia, China, Scott Joshua Friedman
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
As a result of complex extensional tectonics in northeast China and southern portions of Mongolia, some workers have interpreted the Cretaceous Maanshan Uplift and associated Chifeng basins as metamorphic core complex. Previous work has relied solely upon kinematic indicators to determine the structural origin of these basins. To fully understand the creation of these basins, the sedimentiological record was analyzed in this study. The early Cretaceous sedimentary fill of these basins was analyzed to determine if it is synextensional in nature, and if so what manner of extension was in progress during that deposition.
The Chifeng basins are filled with …
Geochemical Provenance Of Clastic Sedimentary Rocks In The Western Cordillera: Utah, Colorado, Wyoming, And Oregon, John Aaron Peterson
Geochemical Provenance Of Clastic Sedimentary Rocks In The Western Cordillera: Utah, Colorado, Wyoming, And Oregon, John Aaron Peterson
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Sedimentary rocks are an important source of information about previous orogenic conditions and the composition of which may describe the evolution of provenance and tectonic setting. Many factors influence sediment composition, namely, source rock composition, chemical weathering, climate, transport burial, and diagenesis. As the sediment composition changes through time, the geochemical characteristics of the sediment can be used to understand its geologic history.
The geochemical characteristics of clastic sedimentary rocks are useful in determining the depositional setting and its associated provenance. Although many different studies have used geochemical discriminants to evaluate provenance and tectonic settings, none have used a defined …
Fluvial Systems Tied Together Through A Common Base Level: The Geomorphic Response Of The Dirty Devil River, North Wash Creek, And The Colorado River To The Rapid Base Level Drop Of Lake Powell, Adam L. Majeski
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Fluvial adjustment to base level change has its roots in the fundamental concepts of geomorphology. This thesis explores the rate of erosion and sedimentation on the Colorado and Dirty Devil rivers and North Wash Creek under the current base level changes related to the drawdown conditions of Lake Powell. Through cross section and long profile resurveys, the current state of each system is captured and added to the historic record of sedimentation in Lake Powell. All three systems are generally forming narrow and deep incised channels driven by the rapid rate of base level fall. Cross sections that deviate from …
Constraints On The Utility Of Mno2 Cartridge Method For The Extraction Of Radionuclides: A Case Study Using 234Th, M. Baskaran, P. W. Swarzenski, B. A. Biddanda
Constraints On The Utility Of Mno2 Cartridge Method For The Extraction Of Radionuclides: A Case Study Using 234Th, M. Baskaran, P. W. Swarzenski, B. A. Biddanda
Environmental Science and Geology Faculty Research Publications
Large volume (102–103 L) seawater samples are routinely processed to investigate the partitioning of particle reactive radionuclides and Ra between solution and size-fractionated suspended particulate matter. One of the most frequently used methods to preconcentrate these nuclides from such large volumes involves extraction onto three filter cartridges (a prefilter for particulate species and two MnO2-coated filters for dissolved species) connected in series. This method assumes that the extraction efficiency is uniform for both MnO2-coated cartridges, that no dissolved species are removed by the prefilter, and that any adsorbed radionuclides are not desorbed from …
The Storm 2.0 Project Next Generation Hurricane Data Collection, Santhana Krishnan Balaji
The Storm 2.0 Project Next Generation Hurricane Data Collection, Santhana Krishnan Balaji
Honors Capstones
No abstract provided.
Hydrometeor-Enhanced Tephra Sedimentation: Constraints From The 18 May 1980 Eruption Of Mount St. Helens, Adam J. Durant, William I. Rose, A. M. Sarna-Wojcicki, S. Carey, A. C. M. Volentik
Hydrometeor-Enhanced Tephra Sedimentation: Constraints From The 18 May 1980 Eruption Of Mount St. Helens, Adam J. Durant, William I. Rose, A. M. Sarna-Wojcicki, S. Carey, A. C. M. Volentik
Department of Geological and Mining Engineering and Sciences Publications
Uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits. In this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the Mount St. Helens 18 May 1980 (MSH80) eruption. In addition, we collate all the data needed to model distal ash sedimentation from the MSH80 eruption cloud. Four particle size subpopulations were present in distal fallout with modes at 2.2 Φ, 4.2 Φ, 5.9 Φ, and 8.3 Φ. Settling rates of the coarsest subpopulation closely matched predicted single-particle terminal …
Variable Uplift From Quaternary Folding Along The Northern Coast Of East Timor, Based On U-Series Age Determinations Of Coral Terraces, Nicole L. Cox
Variable Uplift From Quaternary Folding Along The Northern Coast Of East Timor, Based On U-Series Age Determinations Of Coral Terraces, Nicole L. Cox
Theses and Dissertations
Surveys of emergent terraces and U-series ages for ten sites along the coast of East Timor provide estimates of late Quaternary differential vertical strain in the most mature region of the Banda Arc-continent collision complex. Over a distance of ~180 km vertical displacement rates vary between 0.0 and 1.6 meters per 1000 years for the last 150,000 years. Two models of terrace formation (constructional and erosional) are applied to interpret terrace ages from coral ages and to estimate uplift rates. The highest uplift rates are from three sites over a distance of 15 km along the coast. Uplift rates were …
Holocene Fire And Climate In Rangeland Ecosystems Of Southwestern Idaho, Nathan Alfred Nelson
Holocene Fire And Climate In Rangeland Ecosystems Of Southwestern Idaho, Nathan Alfred Nelson
Boise State University Theses and Dissertations
Because rangelands are characterized by more arid climates than forested regions, traditional methods of reconstructing fire histories (e.g. fire-scars from trees or charcoal preserved in lake sediments) are limited. Charcoal preserved in alluvial fans and stream terraces provide a means of reconstructing a record of fires and geomorphic responses in rangeland ecosystems.
This study used dated charcoal from fire-related deposits and deposit characteristics to determine a record of fire and geomorphic response. Twenty-five samples collected from terraces and alluvial fans within the Wood Creek study area indicate three major periods of fire-related activity. From 4,400 – 4,000 cal yr BP, …
Coesite In Eclogite From The North Qaidam Mountains And Its Implications, Jian-Xin Zhang, Fan-Cong Meng, Jin-Ping Li, Chris G. Mattinson
Coesite In Eclogite From The North Qaidam Mountains And Its Implications, Jian-Xin Zhang, Fan-Cong Meng, Jin-Ping Li, Chris G. Mattinson
All Faculty Scholarship for the College of the Sciences
Coesite provides direct evidence for ultrahigh pressure metamorphism. Although coesite has been found as inclusions in zircon in paragneiss of the north Qaidam Mountains, it has never been identified in eclogite. In this contribution, based on petrographic observations and in situ Raman microprobe spectroscopy, coesite was identified as inclusions in garnet of eclogite from the Aercituoshan, Dulan UHP metamorphic unit, north Qaidam Mountains. Coesite is partly replaced by quartz, showing a palisade texture. This is the first report on coesite in eclogite from the north Qaidam Mountains, and is also supported by garnet-omphacite-phengite geothermobarometry (2.7–3.25 GPa, 670–730°C). Coesite and its …
Basal Mechanics Of Ice Streams: Insights From The Stick-Slip Motion Of Whillans Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Robert A. Bindschadler, Matt A. King
Basal Mechanics Of Ice Streams: Insights From The Stick-Slip Motion Of Whillans Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Robert A. Bindschadler, Matt A. King
All Faculty Scholarship for the College of the Sciences
The downstream portion of Whillans Ice Stream, West Antarctica, moves primarily by stick-slip motion. The observation of stick-slip motion suggests that the bed is governed by velocity-weakening physics and that the basal physics is more unstable than suggested by laboratory studies. The stick-slip cycle of Whillans Ice Plain exhibits substantial variability in both the duration of sticky periods and in slip magnitude. To understand this variability, we modeled the forces acting on the ice stream during the stick phase of the stick-slip cycle. The ocean tides introduce changes in the rate at which stress is applied to the ice plain. …
Significant Seismic Anisotropy Beneath The Southern Lhasa Terrane, Tibetan Plateau, Stephen S. Gao, Kelly H. Liu
Significant Seismic Anisotropy Beneath The Southern Lhasa Terrane, Tibetan Plateau, Stephen S. Gao, Kelly H. Liu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Shear wave splitting measurements using teleseismic PKS, SKKS, and SKS phases recorded by station LSA on the southern part of the Lhasa Terrane of the Tibetan Plateau reveal significant azimuthal anisotropy with a splitting time of up to 1.5 s, a conclusion that is contradictory to previous studies which suggested isotropy or weak anisotropy. In addition, systematic variations of the splitting parameters (fast polarization direction and splitting time) with the arriving azimuth of the seismic ray path are observed, suggesting a model of anisotropy that is more complicated than a single layer with horizontal axis of symmetry. The measurements are …
Effect Of Bacterial Adsorption On Low Frequency Electrical Properties Of Clean Quartz Sands And Iron-Oxide Coated Sands, Gamal Z. Abdel Aal, Estella A. Atekwana, Sylvia Radzikowski, Silvia Rossbach
Effect Of Bacterial Adsorption On Low Frequency Electrical Properties Of Clean Quartz Sands And Iron-Oxide Coated Sands, Gamal Z. Abdel Aal, Estella A. Atekwana, Sylvia Radzikowski, Silvia Rossbach
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Low frequency electrical measurements (0.1-1000 Hz) were conducted to investigate the adsorption effect of Pseudomonas aeruginosa cells onto clean quartz sands and iron-oxide coated sands. The clean quartz sands showed a gradual increase in the microbial adsorption to mineral grains, concurrent with an increase of 13% in the imaginary conductivity component (σ″). However, iron-oxide coated sands (20-100% by weight) showed a rapid increase in microbial adsorption with σ″ reaching a maximum of 37% for the 80-100% iron coated sands. No significant changes were observed in the real conductivity component (σ′) due to microbial adsorption. A power law dependency was observed …
Exhumation Of The Inyo Mountains, California: Implications For The Timing Of Extension Along The Western Boundary Of The Basin And Range Province And Distribution Of Dextral Fault Slip Rates Across The Eastern California Shear Zone, Jeffrey Lee, Daniel F. Stockli, Lewis A. Owen, Robert C. Finkel, Roman Kislitsyn
Exhumation Of The Inyo Mountains, California: Implications For The Timing Of Extension Along The Western Boundary Of The Basin And Range Province And Distribution Of Dextral Fault Slip Rates Across The Eastern California Shear Zone, Jeffrey Lee, Daniel F. Stockli, Lewis A. Owen, Robert C. Finkel, Roman Kislitsyn
All Faculty Scholarship for the College of the Sciences
New geologic mapping, tectonic geomorphologic, 10Be terrestrial cosmogenic nuclide, and (U-Th)/He zircon and apatite thermochronometric data provide the first numerical constraints on late Cretaceous to late Quaternary exhumation of the Inyo Mountains and vertical slip and horizontal extension rates across the eastern Inyo fault zone, California. The east-dipping eastern Inyo fault zone bounds the eastern flank of the Inyo Mountains, a prominent geomorphic feature within the western Basin and Range Province and eastern California shear zone. (U-Th)/He zircon and apatite thermochronometry yield age patterns across the range that are interpreted as indicating: (1) two episodes of moderate to rapid …
Paleomagnetic Behavior Of Volcanic Rocks From Isla Socorro, Mexico, Elise Sbarbori, Lisa Tauxe, Avto Goguitchaichvili, Jaime Urrutia-Fucugauchi, Wendy A. Bohrson
Paleomagnetic Behavior Of Volcanic Rocks From Isla Socorro, Mexico, Elise Sbarbori, Lisa Tauxe, Avto Goguitchaichvili, Jaime Urrutia-Fucugauchi, Wendy A. Bohrson
All Faculty Scholarship for the College of the Sciences
The direction and magnitude of the geomagnetic field vary both spatially and temporally and undergo significant departures from that of a geocentric axial dipole. In order to properly characterize persistent behaviors, time-averaged field models must be based on the highest quality data. Here we present full-vector paleomagnetic data for volcanic units exposed in the southeast quadrant of the island of Socorro, Mexico. We carried out a joint expedition between the Scripps Institution of Oceanography and the Universidad Nacional Autónoma México to Isla Socorro in January of 2005 during which we collected oriented paleomagnetic samples from 21 sites, representing as many …