Assessment Of Corrosion Potential Of Coarse Backfill Aggregates For Mechanically Stabilized Earth Walls,
2011
Missouri University of Science and Technology
Assessment Of Corrosion Potential Of Coarse Backfill Aggregates For Mechanically Stabilized Earth Walls, Anita Thapalia, David M. Borrok, Soheil Nazarian, Jose Garibay
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The service life of mechanically stabilized earth walls depends on the rate of corrosion of the metallic reinforcements used in their construction. The assessment of corrosion potential requires an accurate evaluation of pH, resistivity, and sulfate and chloride concentrations of aqueous solutions in contact with the surrounding aggregate. Highway agencies tend to use larger aggregates that contain only a small amount of fine material (passing the Number 40 sieve) in the backfill. Evaluation of the electrochemical parameters of coarse aggregates is challenging because traditional evaluation methods call for the use of fine material. In this study, the suitability of traditional …
Effects Of High-Impedance-Contrast Boundary Upon Multi-Modal Seismic Surface Wave Data,
2011
University of Nevada, Las Vegas
Effects Of High-Impedance-Contrast Boundary Upon Multi-Modal Seismic Surface Wave Data, Prajwol Tamrakar
UNLV Theses, Dissertations, Professional Papers, and Capstones
Synthetic studies and analyses of an experimental dataset were conducted to address the use of Rayleigh-type surface waves for estimation of shear wave velocity (VS) profiles of shallow bedrock sites. The shallow bedrock presents a high impedance contrast boundary which causes surface wave energy to be partitioned to higher modes. Idealized studies of hypothetical datasets and root-mean-squared calculations of error surfaces showed that if reliable dispersion data are available over a broad frequency spectrum, the VS profile can be recovered using the fundamental mode alone. However, when dispersion data are limited to a relatively narrow frequency band representing what might …
Spring Migration Of Mallards From Arkansas As Determined By Satellite Telemetry,
2011
University of Arkansas
Spring Migration Of Mallards From Arkansas As Determined By Satellite Telemetry, David George Krementz, Kwasi Asante, Luke W. Naylor
United States Geological Survey: Staff Publications
We used satellite telemetry to document spring migration phenology, routes, stopover regions, and nesting sites of mallards Anas platyrhynchos marked in Arkansas during the winters of 2004–2007. Of the 143 marked mallards that migrated from Arkansas, they did so, on average, by mid-March. Mallards flew over the Missouri Ozarks and 42% made an initial stopover in Missouri, where they used areas that had larger rivers (Mississippi River, Missouri River) embedded in an agricultural landscape. From this stopover region they either migrated directly to the Prairie Pothole Region (PPR) or they migrated north to Minnesota where they either moved next to …
Field-Based Constraints On The Origin Of The Benton Uplift, Ouachita Mountains,
2011
University of Arkansas, Fayetteville
Field-Based Constraints On The Origin Of The Benton Uplift, Ouachita Mountains, Rachel Victoria Keng
Graduate Theses and Dissertations
The Ouachita Mountains are an east-west trending fold-and-thrust belt exposed in west central Arkansas and southeastern Oklahoma. The Mississippian-Pennsylvanian Ouachita orogeny occurred when the Sabine arc terrane collided during south-facing subduction, during closure of the Cambrian passive margin of the North American plate. Deep-water Paleozoic strata were incorporated into an accretionary wedge as the Sabine terrane approached the North American plate. Folds and thrust faults in the Ouachita Mountains generally verge north due to tectonic transport of an accretionary wedge from south to north. Structures in the Benton and Broken Bow Uplifts (located in the core of the wedge) locally …
Paired Positive Carbonate Carbon Isotope, Organic Carbon Isotope, And Oxygen Isotope Composition Study Across The Lower Mississippian Positive Carbon Isotope Excursion, Southeastern Nevada, Usa,
2011
University of Nevada, Las Vegas
Paired Positive Carbonate Carbon Isotope, Organic Carbon Isotope, And Oxygen Isotope Composition Study Across The Lower Mississippian Positive Carbon Isotope Excursion, Southeastern Nevada, Usa, Robert Alan Henry
UNLV Theses, Dissertations, Professional Papers, and Capstones
A prominent positive carbonate carbon isotope (delta13Ccarb) excursion of Early Mississippian age (ca 351 Ma) has been documented by previous studies from numerous sites globally. This delta13Ccarb excursion has been interpreted as resulting from enhanced organic carbon burial that removed 13C-depleted carbon from the ocean and atmosphere. Anticipated outcomes from enhanced organic carbon burial would include a similar positive excursion in organic carbon isotopes (delta13Corg) and a global cooling event resulting from reduced CO2 in the atmosphere and ocean. These predictions, however, were not tested sufficiently in previous studies. This research has tested these predictions through an integrated study of …
Microstructural Characterization Of Kinked Germanate Olivine Grains,
2011
University of Nevada, Las Vegas
Microstructural Characterization Of Kinked Germanate Olivine Grains, Alex Gregory Drue
UNLV Theses, Dissertations, Professional Papers, and Capstones
Olivine is the most common and the weakest mineral in the upper mantle. Thus the strength of olivine controls the rheology of the earth's upper mantle. The rheology of olivine in the upper mantle has important implications for mantle flow, mountain building, and rates of isostatic adjustment. Recent experimental measurements of the flow strength of deformed olivine polycrystals have assumed a homogeneous state of stress. X-ray synchrotron diffraction experiments have implied that this assumption is not always valid. Elastic Plastic Self Consistent (EPSC) modeling offers an approach to estimating the flow strength of olivine that does not assume a homogeneous …
Magma Chamber Processes At Mutnovsky Volcano, Russia,
2011
University of Nevada, Las Vegas
Magma Chamber Processes At Mutnovsky Volcano, Russia, Kelly L. Robertson
UNLV Theses, Dissertations, Professional Papers, and Capstones
This dissertation is composed of two manuscripts about the evolution of Mutnovsky Volcano in Kamchatka, Russia. Mutnovsky has been active for the past approximately 80,000 years, during which there was the formation and subsequent eruption of four major stratocones. These four eruptive centers, named Mutnovsky I, II, III, and IV from oldest to youngest, have a range of erupted product compositions from basalt to dacite. The first major goal of this project was to investigate the melt source for Mutnovsky. Whole rock trace element and Nd, Sr, and Pb isotopic data were used to determine that the melt source was …
Stratigraphic Record Of Holocene Coseismic Subsidence, Padang, West Sumatra,
2011
University of Pennsylvania
Stratigraphic Record Of Holocene Coseismic Subsidence, Padang, West Sumatra, Tina Dura, Charles M. Rubin, Harvey M. Kelsey, Benjamin P. Horton, Andrea Hawkes, Christopher H. Vane, Mudrik Daryono, Candace Grand Pre, Tyler Landinsky, Sarah Bradley
All Faculty Scholarship for the College of the Sciences
Stratigraphic evidence is found for two coseismic subsidence events that underlie a floodplain 20 km south of Padang, West Sumatra along the Mentawai segment (0.5°S–0.3°S) of the Sunda subduction zone. Each earthquake is marked by a sharp soil‐mud contact that represents a sudden change from mangrove to tidal flat. The earthquakes occurred about 4000 and 3000 cal years B.P. based on radiocarbon ages of detrital plant fragments and seeds. The absence of younger paleoseismic evidence suggests that late Holocene relative sea level fall left the floodplain too high for an earthquake to lower it into the intertidal zone. Our results …
Sequence Stratigraphy Of Basal Oquirrh Group Caronates (Bashkirian) Thorpe Hills, Lake Mountain, Wasatch Front, Utah,
2011
Brigham Young University - Provo
Sequence Stratigraphy Of Basal Oquirrh Group Caronates (Bashkirian) Thorpe Hills, Lake Mountain, Wasatch Front, Utah, Andrew D. Derenthal
Theses and Dissertations
The Early Pennsylvanian (Bashkirian/Morrowan) Bridal Veil Limestone of north-central Utah was deposited in the eastern portion of the rapidly subsiding Oquirrh basin. The 420 meter-thick Bridal Veil Limestone displays distinct cyclicity formed by stacked, meter to decameter scale high-frequency sequences and their constituent parasequences. Though no one ideal cycle may be defined for the Bridal Veil Limestone, each high-frequency sequence and parasequence contains a general shallowing upward trend that ranges from anaerobic to dysaerobic mudstone at the base to skeletal wackestone to mud-dominated packstone, capped by heterozoan grain-rich carbonates or siliciclastic tidalites. Cycles bounded by exposure surfaces, indicated by micro-brecciation, …
Suspended Sediment Concentration In The Brushy Creek Watershed, Kentucky,
2011
Eastern Kentucky University
Suspended Sediment Concentration In The Brushy Creek Watershed, Kentucky, Tyler Wade, Walter S. Borowski
EKU Faculty and Staff Scholarship
Suspended sediment concentration (SSC) can be used as a proxy for environmental health of stream water. For example, large sediment loads can cause harm to aquatic life and are a mechanism for introducing and transporting fecal microbes. We measure SSC of the Brushy Creek watershed, located in Rockcastle, Pulaski, and Lincoln Counties, where the Eastern Kentucky Environmental Research Institute (EK-ERI) has been conducting an assessment of the watershed. Two auto sampling units were placed in Brushy Creek to collect water samples for determination of SSC. The units collect samples every 14 hours for a two-week period, then samples are retrieved …
Magnetic Susceptibility As A Proxy For Investigating Microbially Mediated Iron Reduction,
2011
Missouri University of Science and Technology
Magnetic Susceptibility As A Proxy For Investigating Microbially Mediated Iron Reduction, Farag M. Mewafy, Estella A. Atekwana, D. Dale Werkema, Lee D. Slater, Dimitrios Ntarlagiannis, Andre Revil, Magnus E. Skold, Geoffrey N. Delin
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
We investigated magnetic susceptibility (MS) variations in hydrocarbon contaminated sediments. Our objective was to determine if MS can be used as an intrinsic bioremediation indicator due to the activity of iron-reducing bacteria. A contaminated and an uncontaminated core were retrieved from a site contaminated with crude oil near Bemidji, Minnesota and subsampled for MS measurements. The contaminated core revealed enriched MS zones within the hydrocarbon smear zone, which is related to iron-reduction coupled to oxidation of hydrocarbon compounds and the vadose zone, which is coincident with a zone of methane depletion suggesting aerobic or anaerobic oxidation of methane is coupled …
Stress Modulation On The San Andreas Fault By Interseismic Fault System Interactions,
2011
Harvard University
Stress Modulation On The San Andreas Fault By Interseismic Fault System Interactions, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
During the interseismic phase of the earthquake cycle, between large earthquakes, stress on faults evolves in response to elastic strain accumulation driven by tectonic plate motions. Because earthquake cycle processes induce non-local stress changes, the interseismic stress accumulation rate on one fault is influenced by the behavior of all nearby faults. Using a geodetically constrained block model, we show that the total interseismic elastic strain field generated by fault interactions within Southern California may increase stressing rates on the Mojave and San Bernardino sections of the San Andreas fault within the Big Bend region by as much as 38% relative …
Linkages Between East Antarctic Ice Sheet Extent And Southern Ocean Temperatures Based On A Pliocene High‐Resolution Record Of Ice‐Rafted Debris Off Prydz Bay, East Antarctica,
2011
Montclair State University
Linkages Between East Antarctic Ice Sheet Extent And Southern Ocean Temperatures Based On A Pliocene High‐Resolution Record Of Ice‐Rafted Debris Off Prydz Bay, East Antarctica, Sandra Passchier
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
[1] Ice‐rafted debris mass accumulation rates (IRD MAR) at a drill site on the Antarctic continental margin are investigated to evaluate the linkages between East Antarctic Ice Sheet extent and Southern Ocean temperatures in the early to mid‐Pliocene. ODP Site 1165 is within 400 km of the Antarctic coastline and in the direct pathway of icebergs released by the Amery Ice Shelf. The Amery Ice Shelf is the largest ice shelf in East Antarctica and it buttresses the Lambert Glacier drainage system, which accounts for 14% of the outflow from the East Antarctic Ice Sheet. IRD MAR were low during …
Quasi 3-Dimensional Electrical Resistivity Mapping Of Air-Filled Karst Conduits And Policy Implications,
2011
University of South Florida
Quasi 3-Dimensional Electrical Resistivity Mapping Of Air-Filled Karst Conduits And Policy Implications, Charles W. Mccrackin
USF Tampa Graduate Theses and Dissertations
This study assesses the capability and practical applications of quasi 3-Dimensional (3D) electrical resistivity surveying (ER) for mapping air-filled karst conduits. Vadose zone caves within the Brooksville Ridge of West Central Florida are relatively similar in architecture, with N-S elongation, and do not consist of an interconnected network of conduits. A high resolution quasi-3D ER survey was performed over two mapped cave systems on the Brooksville Ridge. The resultant survey verified the general effectiveness of quasi-3D ER in locating the two known near-surface cave features. Several other locations in the survey show similar or stronger resistivity anomalies trending in a …
Dissemination Of Geological Information In Avoiding Geotechnical Risks Associated With Tunnel Construction: Lessons Learned From Deep Voids In Marble In Lower Manhattan, New York City,
2011
CUNY York College
Dissemination Of Geological Information In Avoiding Geotechnical Risks Associated With Tunnel Construction: Lessons Learned From Deep Voids In Marble In Lower Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Leah Scott
Publications and Research
Test boring associated with the recently accomplished City Water Tunnel # 3 in Manhattan, New York City revealed moderately to highly weathered marble with insoluble silicate residues composed mostly of phlogopite, chlorite, and tremolite. Apparent control on the weatherability of the marble was in response to original mineral constituents dominating this lithology. Encountered marble samples ranged between pure calcitic to mixed dolomitic/siliceous types. Fresh marble samples collected from adjacent boring locations revealed characteristic geochemical data: Lime (25-45%), Silica (4-7%), Alumina (1-3%), MgO (5-20%), and LOI (35-42%); compressive strength of unweathered marble varied between 2000-3000 Kg/cm2. Relict foliations with …
Insight Into Volatile Behavior At Nyamuragira Volcano (D.R. Congo, Africa) Through Olivine-Hosted Melt Inclusions,
2011
Eastern Illinois University
Insight Into Volatile Behavior At Nyamuragira Volcano (D.R. Congo, Africa) Through Olivine-Hosted Melt Inclusions, Elisabet M. Head, Alison M. Shaw, Paul J. Wallace, Kenneth W. W. Sims, Simon A. Carn
Faculty Research and Creative Activity
[1] We present new olivine-hosted melt inclusion volatile (H20, C02, S, Cl, F) and major element data from five historic eruptions ofNyamuragira volcano (1912, 1938, 1948, 1986, 2006). Host-olivine Mg#'s range from 71 to 84, with the exception of the 1912 sample (Mg# = 90}.lnclusion compositions extend from alkali basalts to basanite-tephritcs. Our results indicate inclusion entrapment over depths ranging from 3 to 5 km, which agree with independent estimates of magma storage depths (3-7 km) based on geophysical methods. Melt compositions derived from the 1986 and 2006 Nyamuragira tephra samples best represent pre-eruptive volatile compositions because these samples contain …
Post-Fire Near-Surface Runoff From Small-Scale Rainfall Simulations, Santa Cruz Mountains,
2011
California Polytechnic State University, San Luis Obispo
Post-Fire Near-Surface Runoff From Small-Scale Rainfall Simulations, Santa Cruz Mountains, Michael Founds
Natural Resources Management and Environmental Sciences
The influence of environmental variables on the runoff response to a fire is poorly understood. Small-scale rainfall simulation was used to study the factors impacting near-surface runoff following the Lockheed Fire, which occurred on August 12, 2009. A variable speed rainfall simulator was used to rain on 15 different test plots at an average rate of 50mmh-1. Variables of burn severity, time following the fire, soil parent material, vegetation type, and presence of a duff layer were all analyzed using the ratio of runoff to rainfall. The difference in-between burned sites and similar control sites were 19±6%. Only …
Geogram 2011,
2011
Western Kentucky University
Geogram 2011, David J. Keeling Editor, Wku Department Of Geography And Geology
Earth, Environmental, and Atmospheric Sciences Publications
No abstract provided.
Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'",
2011
Missouri University of Science and Technology
Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'", Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray
Physics Faculty Research & Creative Works
The main criticism raised in the preceding Comment concerns our suggestion that sharp conduction peaks in Bi2Sr2CaCu2O 8+δ mesas, along with absent dip-hump features, may, in general, be a result of self-heating. The author points to the variety of experimental configurations, matrix-element effects, and doping dependencies that might allow a diversity of conductance spectra. We argue that numerous mesa studies (with fixed matrix elements) firmly establish the systematic development of sharp conductance peaks with increased self-heating, and thus, the issue of nonuniversality of tunneling characteristics is not relevant. The author mentions a number of studies that …
Estimation Of The Depth Of Anisotropy Using Spatial Coherency Of Shear-Wave Splitting Parameters,
2011
Missouri University of Science and Technology
Estimation Of The Depth Of Anisotropy Using Spatial Coherency Of Shear-Wave Splitting Parameters, Kelly H. Liu, Stephen S. Gao
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Shear-wave splitting (SWS) analyses are essential in understanding the structure and dynamics of the Earth's deep interior. While splitting measurements have excellent horizontal resolution relative to other anisotropy-measuring techniques, their vertical resolution is low due to the steep incidence angle of the seismic phases used by the analyses. Here, using synthetic and real data, we present and test a simple approach to estimate the optimal depth of anisotropy by measuring the spatial coherency of the splitting parameters. The approach searches for the optimal depth by computing a spatial variation factor. Tests using synthetic SWS data produced with varying number of …
