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Articles 1 - 30 of 42
Full-Text Articles in Geophysics and Seismology
Accurate Inversion Of High-Resolution Snow Penetrometer Signals For Microstructural And Micromechanical Properties, Hans-Peter Marshall, Jerome B. Johnson
Accurate Inversion Of High-Resolution Snow Penetrometer Signals For Microstructural And Micromechanical Properties, Hans-Peter Marshall, Jerome B. Johnson
CGISS Publications and Presentations
Measurements of snow using a high-resolution micropenetrometer can be used to discriminate between different snow types; in lower-density snow the signal is sensitive to microstructure, and micromechanical properties can be estimated. Although a physics-based snow penetration theory was first developed almost a decade ago, since that time the majority of studies using snow micropenetrometers have focused on using direct hardness measurements in statistical relationships. We use Monte-Carlo simulations to rigorously test the existing physics-based snow micropenetration theories over a wide range of parameters. These tests revealed four major sources of error in the inversion, which are corrected in this analysis. …
Plains Co2 Reduction (Pcor) Partnership Atlas, Wesley D. Peck, Katherine K. Anagnost, Barry W. Botnen, Lisa S. Botnen, Daniel J. Daly, Charles D. Gorecki, Megan M. Grove, John A. Harju, Melanie D. Jensen, Michael L. Jones, Steven A. Smith, James A. Sorensen, Edward N. Steadman, Stephanie L. Wolfe, Andrea T. Mcnemar, John T. Litynski, Sean I. Plasynski
Plains Co2 Reduction (Pcor) Partnership Atlas, Wesley D. Peck, Katherine K. Anagnost, Barry W. Botnen, Lisa S. Botnen, Daniel J. Daly, Charles D. Gorecki, Megan M. Grove, John A. Harju, Melanie D. Jensen, Michael L. Jones, Steven A. Smith, James A. Sorensen, Edward N. Steadman, Stephanie L. Wolfe, Andrea T. Mcnemar, John T. Litynski, Sean I. Plasynski
EERC Maps and Infographics
The Plains CO2 Reduction (PCOR) atlas, 3rd edition, introduces global climate change and provides a regional profile of CO2 sources and potential sinks across the PCOR Partnership region. Carbon storage offers a promising set of technologies through which CO2 can be stored for long periods of time.
Modeling Soil Depth From Topographic And Land Cover Attributes, Teklu K. Tesfa, David G. Tarboton, David G. Chandler, James P. Mcnamara
Modeling Soil Depth From Topographic And Land Cover Attributes, Teklu K. Tesfa, David G. Tarboton, David G. Chandler, James P. Mcnamara
Geosciences Faculty Publications and Presentations
Soil depth is an important input parameter in hydrological and ecological modeling. Presently, the soil depth data available in national soil databases (STATSGO and SSURGO) from the Natural Resources Conservation Service are provided as averages within generalized land units (map units). Spatial uncertainty within these units limits their applicability for distributed modeling in complex terrain. This work reports statistical models for prediction of soil depth in a semiarid mountainous watershed that are based upon the relationship between soil depth and topographic and land cover attributes. Soil depth was surveyed by driving a rod into the ground until refusal at locations …
Infrasonic Ambient Noise Interferometry From Correlations Of Microbaroms, Matthew M. Haney
Infrasonic Ambient Noise Interferometry From Correlations Of Microbaroms, Matthew M. Haney
CGISS Publications and Presentations
We show that microbaroms, continuous infrasound fluctuations resulting from the interaction of the ocean with the atmosphere, have long-range correlation properties that make it possible to estimate the impulse response between two microphones from passive recordings. The processing is analogous to methods employed in the emerging field of ambient noise seismology, where the random noise source is the ocean coupling with the solid Earth (microseisms) instead of the atmosphere (microbaroms). We find that timedependent temperature fields and temperature inversions determine the character of infrasonic impulse responses at Fourpeaked Volcano in Alaska. Applications include imaging and monitoring the gross structure of …
Geogram 2009, David J. Keeling Editor, Wku Department Of Geography And Geology
Geogram 2009, David J. Keeling Editor, Wku Department Of Geography And Geology
Earth, Environmental, and Atmospheric Sciences Publications
No abstract provided.
Estimating Debye Parameters From Gpr Reflection Data Using Spectral Ratios, John H. Bradford
Estimating Debye Parameters From Gpr Reflection Data Using Spectral Ratios, John H. Bradford
Geosciences Faculty Publications and Presentations
In the GPR frequency range, electromagnetic wave attenuation is largely controlled by dielectric relaxation processes. A primary relaxation commonly occurs in the 10 – 100 MHz range for many earth materials in which the GPR signal propagates effectively. This relaxation leads to strong nonlinearity in the frequency dependent attenuation and occurs in a frequency range that is often used for groundwater investigations. This non-linearity complicates data analysis but also may provide additional material property information. I investigate inversion for Debye relaxation parameters directly from GPR reflection data, including increasing the bandwidth of the signal by summing the response from 25 …
Improved Confidence In (U-Th)/He Thermochronology Using The Laser Microprobe: An Example From A Pleistocene Leucogranite, Nanga Parbat, Pakistan, J. W. Boyce, K. V. Hodges, D. King, James L. Crowley, M. Jercinovic, N. Chatterjee, S. A. Bowring, M. Searle
Improved Confidence In (U-Th)/He Thermochronology Using The Laser Microprobe: An Example From A Pleistocene Leucogranite, Nanga Parbat, Pakistan, J. W. Boyce, K. V. Hodges, D. King, James L. Crowley, M. Jercinovic, N. Chatterjee, S. A. Bowring, M. Searle
Geosciences Faculty Publications and Presentations
The newly developed laser microprobe (U-Th)/He thermochronometer permits, for the first time, the ability to generate precise (U-Th)/He cooling ages for even very young (Ma) samples with a spatial resolution on the order of tens of micrometers. This makes it possible to test the reproducibility of independent (U-Th)/He age determinations within individual crystals, further increasing the reliability of the method. As an example, we apply it here to a Pleistocene granite from Nanga Parbat, Pakistan, where previous constraints on the thermal history are consistent with rapid exhumation and cooling. Twenty-one (U-Th)/He dates determined on two monazite crystals from a single …
Understanding Paleoclimate And Human Evolution Through The Hominin Sites And Paleolakes Drilling Project, Andrew Cohen, Ramon Arrowsmith, Anna K. Behrensmeyer, Christopher Campisano, Craig Feibel, Shimeles Fisseha, Roy Johnson, Zelalem Bedaso, Charles Lockwood, Emma Mbua, Daniel Olago, Richard Potts, Kaye Reed, Robin Renaut, Jean-Jacques Tiercelin, Mohammed Umer
Understanding Paleoclimate And Human Evolution Through The Hominin Sites And Paleolakes Drilling Project, Andrew Cohen, Ramon Arrowsmith, Anna K. Behrensmeyer, Christopher Campisano, Craig Feibel, Shimeles Fisseha, Roy Johnson, Zelalem Bedaso, Charles Lockwood, Emma Mbua, Daniel Olago, Richard Potts, Kaye Reed, Robin Renaut, Jean-Jacques Tiercelin, Mohammed Umer
Department of Earth, Environment and Sustainability Faculty Publications
Understanding the evolution of humans and our close relatives is one of the enduring scientific issues of modern times. Since the time of Charles Darwin, scientists have speculated on how and when we evolved and what conditions drove this evolutionary story. The detective work required to address these questions is necessarily interdisciplinary, involving research in anthropology, archaeology, human genetics and genomics, and the earth sciences. In addition to the difficult tasks of finding, describing, and interpreting hominin fossils (the taxonomic tribe which includes Homo sapiens and our close fossil relatives from the last 6 Ma), much of modern geological research …
Geometry Of The Trachyte Mesa Intrusion, Henry Mountains, Utah: Implications For The Emplacement Of Small Melt Volumes Into The Upper Crust, Paul H. Wetmore, Charles B. Connor, Sarah E. Kruse, Sean Callihan, Geoffrey Pignotta, Ciprian Stremtan, Andrea Burke
Geometry Of The Trachyte Mesa Intrusion, Henry Mountains, Utah: Implications For The Emplacement Of Small Melt Volumes Into The Upper Crust, Paul H. Wetmore, Charles B. Connor, Sarah E. Kruse, Sean Callihan, Geoffrey Pignotta, Ciprian Stremtan, Andrea Burke
Geology Faculty Publications
The Trachyte Mesa intrusion is one of several small satellite bodies to the larger intrusions of the Henry Mountains, Utah. Most previous studies have worked under the assumptions that Trachyte Mesa is blister shaped and intruded into flat and gently NW dipping strata. In this study we combine structural and geophysical data sets to constrain the structural geology of the host lithologies and the unmodified geometry of the intrusion. Trachyte Mesa intrudes a series of northeast trending upright and open folds formed within the Jurassic Entrada Formation. Truncation of these folds at the contact with the overlying Curtis/Summerville formations indicates …
Obtaining Parsimonious Hydraulic Conductivity Fields Using Head And Transport Observations: A Bayesian Geostatistical Parameter Estimation Approach, Michael Fienen, R. Hunt, D. Krabbenhoft, Tom Clemo
Obtaining Parsimonious Hydraulic Conductivity Fields Using Head And Transport Observations: A Bayesian Geostatistical Parameter Estimation Approach, Michael Fienen, R. Hunt, D. Krabbenhoft, Tom Clemo
CGISS Publications and Presentations
Flow path delineation is a valuable tool for interpreting the subsurface hydrogeochemical environment. Different types of data, such as groundwater flow and transport, inform different aspects of hydrogeologic parameter values (hydraulic conductivity in this case) which, in turn, determine flow paths. This work combines flow and transport information to estimate a unified set of hydrogeologic parameters using the Bayesian geostatistical inverse approach. Parameter flexibility is allowed by using a highly parameterized approach with the level of complexity informed by the data. Despite the effort to adhere to the ideal of minimal a priori structure imposed on the problem, extreme contrasts …
Complex Dielectric Permittivity Measurements From Ground-Penetrating Radar Data To Estimate Snow Liquid Water Content In The Pendular Regime, John H. Bradford, Joel T. Harper, Joel Brown
Complex Dielectric Permittivity Measurements From Ground-Penetrating Radar Data To Estimate Snow Liquid Water Content In The Pendular Regime, John H. Bradford, Joel T. Harper, Joel Brown
CGISS Publications and Presentations
Monitoring the snow water equivalent (SWE) is critical to effective management of water resources in many parts of the world that depend on the mountain snowpack for water storage. There are currently no methods to remotely sense SWE with accuracy over large lateral distances in the steep and often forested terrain of mountain basins. Previous studies have shown that measurements of ground-penetrating radar (GPR) velocity can provide accurate estimates of SWE in dry snow. Introduction of liquid water into the snowpack results in a three-phase system that cannot be accurately characterized with GPR velocity alone. We show that measuring the …
Moment Release Rate Of Cascadia Tremor Constrained By Gps, Ana C. Aguiar, Timothy I. Melbourne, Craig W. Scrivner
Moment Release Rate Of Cascadia Tremor Constrained By Gps, Ana C. Aguiar, Timothy I. Melbourne, Craig W. Scrivner
All Faculty Scholarship for the College of the Sciences
A comparison of GPS and seismic analyses of 23 distinct episodic tremor and slip events, located throughout the Cascadia subduction zone over an 11-year period, yields a highly linear relationship between moment release, as estimated from GPS, and total duration of nonvolcanic tremor, as summed from regional seismic arrays. The events last 1–5 weeks, typically produce ~5 mm of static forearc deformation, and show cumulative totals of tremor that range from 40 to 280 h. Moment released by each event is estimated by inverting GPS-measured deformation, which is sensitive to all rates of tremor-synchronous faulting, including aseismic creep, for total …
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 …
Seismic Wave Attenuation In Carbonates, Ludmila Adam, M. Batzle, K. T. Lewallen, Kasper Van Wijk
Seismic Wave Attenuation In Carbonates, Ludmila Adam, M. Batzle, K. T. Lewallen, Kasper Van Wijk
CGISS Publications and Presentations
The effect of pore fluids on seismic wave attenuation in carbonate rocks is important for interpreting remote sensing observations of carbonate reservoirs undergoing enhanced oil recovery. Here we measure the elastic moduli and attenuation in the laboratory for five carbonate samples with 20% to 30% porosity and permeability between 0.03 and 58.1 mdarcy. Contrary to most observations in sandstones, bulk compressibility losses dominate over shear wave losses for dry samples and samples fully saturated with either liquid butane or brine. This observation holds for four out of five samples at seismic (10–1000 Hz) and ultrasonic frequencies (0.8 MHz) and reservoir …
Mantle Transition Zone Structure Beneath Kenya And Tanzania: More Evidence For A Deep-Seated Thermal Upwelling In The Mantle, Audrey D. Huerta, Andrew A. Nyblade, Angela M. Reusch
Mantle Transition Zone Structure Beneath Kenya And Tanzania: More Evidence For A Deep-Seated Thermal Upwelling In The Mantle, Audrey D. Huerta, Andrew A. Nyblade, Angela M. Reusch
Geological Sciences Faculty Scholarship
Here we investigate the thermal structure of the mantle beneath the eastern Branch of the East African Rift system in Kenya and Tanzania. We focus on the structure of the mantle transition zone, as delineated by stacking of receiver functions. The top of the transition zone (the 410 km discontinuity) displays distinctive topography, and is systematically depressed beneath the rift in Kenya and northern Tanzania and adjacent volcanic fields. This depression is indicative of a localized ∼350 °C thermal anomaly. In contrast, the bottom of the transition zone (the 660 km discontinuity) is everywhere depressed. This region-wide depression is best …
Observation And Modeling Of Source Effects In Coda Wave Interferometry At Pavlof Volcano, Matthew M. Haney, Kasper Van Wijk, Leiph A. Preston, David F. Aldridge
Observation And Modeling Of Source Effects In Coda Wave Interferometry At Pavlof Volcano, Matthew M. Haney, Kasper Van Wijk, Leiph A. Preston, David F. Aldridge
CGISS Publications and Presentations
We examine seismic records of repeating explosions from Pavlof volcano, Alaska, during its 2007 eruption. Repetitive explosions are typical of Strombolian-style eruptions and allow measurement of relative time shifts between similar late-arriving phases using the technique called coda wave interferometry (Snieder et al., 2002). The measurements enable the detection of small changes in the volcanic interior of Pavlof. We are able to resolve an increase in the relative traveltime change of late-arriving seismic waves on the order of 0.3% over the course of two weeks. Based on the spectra of the explosions, their location inside the magma conduit, previous studies …
Numerical Modeling Of Time-Lapse Seismic Experiments To Monitor Co2 Sequestration In A Layered Basalt Reservoir, Murari Khatiwada
Numerical Modeling Of Time-Lapse Seismic Experiments To Monitor Co2 Sequestration In A Layered Basalt Reservoir, Murari Khatiwada
Boise State University Theses and Dissertations
Instead of allowing carbon dioxide (CO2) generated from the burning of hydrocarbons to escape into the atmosphere, CO2 can be captured and stored. For the long term mitigation of the increasing amount of CO2 emissions, its sequestration in geological formations is promising. As a measure, its short and long term monitoring is equally important for environmental and health safety issues. The seismic method is proposed as a non-invasive monitoring technique for geological sequestration of CO2. Based on the positive results obtained from reservoir monitoring during enhanced oil recovery with CO2 floods, geoscientists plan …
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.
Capacitive Conductivity Logging And Electrical Stratigraphy In A High-Resistivity Aquifer, Boise Hydrogeophysical Research Site, C. Jonathan Mwenifumbo, Warren Barrash, Michael D. Knoll
Capacitive Conductivity Logging And Electrical Stratigraphy In A High-Resistivity Aquifer, Boise Hydrogeophysical Research Site, C. Jonathan Mwenifumbo, Warren Barrash, Michael D. Knoll
CGISS Publications and Presentations
We tested a prototype capacitive-conductivity borehole tool in a shallow, unconfined aquifer with coarse, unconsolidated sediments and very-low-conductivity water at the Boise Hydrogeophysical Research Site (BHRS). Examining such a high-resistivity system provides a good test for the capacitive- conductivity tool because the conventional induction- conductivity tool (known to have limited effectiveness in high-resistivity systems) did not generate expressive well logs at the BHRS. The capacitive-conductivity tool demonstrated highly repeatable, low-noise behavior but poor correlation with the induction tool in the lower-conductivity portions of the stratigraphy where the induction tool was relatively unresponsive. Singular spectrum analysis of capacitive- conductivity logs reveals …
The Virtual Refraction: Useful Spurious Energy In Seismic Interferometry, Dylan Mikesell, Kasper Van Wijk, Alexander Calvert, Matthew M. Haney
The Virtual Refraction: Useful Spurious Energy In Seismic Interferometry, Dylan Mikesell, Kasper Van Wijk, Alexander Calvert, Matthew M. Haney
CGISS Publications and Presentations
Seismic interferometry is rapidly becoming an established technique to recover the Green’s function between receivers, but practical limitations in the source-energy distribution inevitably lead to spurious energy in the results. Instead of attempting to suppress all such energy, we use a spurious wave associated with the crosscorrelation of refracted energy at both receivers to infer estimates of subsurface parameters. We named this spurious event the virtual refraction. Illustrated by a numerical two-layer example, we found that the slope of the virtual refraction defines the velocity of the faster medium and that the stationary-phase point in the correlation gather provides the …
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.
Kinematic Behavior Of Southern Alaska Constrained By Westward Decreasing Postglacial Slip Rates On The Denali Fault, Alaska, A.-S. Mériaux, K. Sieh, R. C. Finkel, Charles M. Rubin, M. H. Taylor, A. J. Meltzner, F. J. Ryerson
Kinematic Behavior Of Southern Alaska Constrained By Westward Decreasing Postglacial Slip Rates On The Denali Fault, Alaska, A.-S. Mériaux, K. Sieh, R. C. Finkel, Charles M. Rubin, M. H. Taylor, A. J. Meltzner, F. J. Ryerson
All Faculty Scholarship for the College of the Sciences
Long‐term slip rates for the Denali Fault in southern Alaska are derived using 10Be cosmogenic radionuclide (CRN) dating of offset glacial moraines at two sites. Correction of 10Be CRN model ages for the effect of snow shielding uses historical, regional snow cover data scaled to the site altitudes. To integrate the time variation of snow cover, we included the relative changes in effective wetness over the last 11 ka, derived from lake‐level records and δ 18O variations from Alaskan lakes. The moraine CRN model ages are normally distributed around an average of 12.1 ± 1.0 ka (n …
Role Of Forward Model In Surface-Wave Studies To Delineate A Buried High-Velocity Layer, Xiaohui Jin, Barbara Luke, Carlos Calderon-Macias
Role Of Forward Model In Surface-Wave Studies To Delineate A Buried High-Velocity Layer, Xiaohui Jin, Barbara Luke, Carlos Calderon-Macias
Civil and Environmental Engineering and Construction Faculty Research
Procedures are tested and compared for processing Rayleigh surface wave data to obtain one-dimensional shear wave velocity profiles for a hypothetical site that contains a buried high-velocity layer (HVL). The main purpose of such an investigation would be to discriminate and characterize the HVL. When target dispersion curves are derived from synthetic time histories, for the most part, the HVL is better identified when profiles are inverted using only the fundamental mode of Rayleigh wave propagation, rather than a more compatible but more complex forward model. The outcomes imply that in practice, a simple forward model might be more successful …
Estimating Porosity With Ground-Penetrating Radar Reflection Tomography: A Controlled 3-D Experiment At The Boise Hydrogeophysical Research Site, John H. Bradford, William P. Clement, Warren Barrash
Estimating Porosity With Ground-Penetrating Radar Reflection Tomography: A Controlled 3-D Experiment At The Boise Hydrogeophysical Research Site, John H. Bradford, William P. Clement, Warren Barrash
CGISS Publications and Presentations
To evaluate the uncertainty of water-saturated sediment velocity and porosity estimates derived from surface-based, ground-penetrating radar reflection tomography, we conducted a controlled field experiment at the Boise Hydrogeophysical Research Site (BHRS). The BHRS is an experimental well field located near Boise, Idaho. The experimental data set consisted of 3-D multioffset radar acquired on an orthogonal 20 × 30 m surface grid that encompassed a set of 13 boreholes. Experimental control included (1) 1-D vertical velocity functions determined from traveltime inversion of vertical radar profiles (VRP) and (2) neutron porosity logs. We estimated the porosity distribution in the saturated zone using …
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. …
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 …
Experimental Evidence Of Non-Linear Dissipation Using Acoustic Micro-Lapses, G. Quiroga-Goode, K. Van Wijk
Experimental Evidence Of Non-Linear Dissipation Using Acoustic Micro-Lapses, G. Quiroga-Goode, K. Van Wijk
Geosciences Faculty Publications and Presentations
Non-linear material behaviour is observed experimentally in a laboratory using a new method called Acoustic Micro-Lapses (AML). In this approach, the shooting of two waves is synchronised in a way that the second wave (TW) is to sense the fluctuations in material stiffness induced by the first (PW). The tests include four samples; twenty trials are performed for each sample by increasing time-delays between the waves. The recorded waves are decoupled and compared to determine spectral differences by computing a quantity proportional to the energy difference as function of the increasing time delay (). For a tight sandstone and aluminium …
Crustal Modification By Tectonic Events And Upper Mantle Anisotropy Beneath The Midcontinent Rift And New Madrid Seismic Zone: Insights From Receiver Function Studies And Teleseismic Shear Wave Splitting, Moikwathai Moidaki
Doctoral Dissertations
"The earth's crust and upper mantle have been continually modified by tectonic processes such as rifting, earthquake activity. In this dissertation, shear wave splitting and receiver function techniques were employed to study the extent of crustal and upper mantle modifications beneath the New Madrid Seismic Zone (NMSZ) and the Midcontinent Rift (MCR). Shear wave splitting analysis in the MCR reveals the presence of fossilised anisotropy along the rift axis...In the NMSZ, anticipated rift-parallel fast directions associated with vertical magmatic dikes or along-rift flow, rift-orthogonal fast directions from small-scale convection, or reduction in splitting times as a result of vertical asthenospheric …
The Cretaceous-Paleogene Transition In The Northern Mississippi Embayment, S.E. Missouri: Palynology, Micropaleontology, And Evidence Of A Mega-Tsunami Deposit, Tambra L. Eifert
The Cretaceous-Paleogene Transition In The Northern Mississippi Embayment, S.E. Missouri: Palynology, Micropaleontology, And Evidence Of A Mega-Tsunami Deposit, Tambra L. Eifert
Doctoral Dissertations
"Upper Cretaceous to lower Paleogene sedimentary rocks in Southeastern Missouri record the northwest extension of the Mississippi Embayment, yet very little information exists about them due to lack of exposures. Access to borehole and trench material and well logs provided an opportunity to study the sedimentology, palynology and micropaleontology of the three formations spanning the Cretaceous-Paleogene (K-Pg) boundary interval: Owl Creek (Cretaceous) and Clayton and Porters Creek (Paleocene). Lithologic features, palynomorphs (mainly spores, pollen, dinoflagellate cysts), dispersed organic matter, and foraminifera were used to interpret biostratigraphy, paleovegetation, paleoclimatic and depositional conditions, thereby creating a framework upon which further questions involving …
Models Of Garnet Differential Geochronology, Matthew J. Kohn
Models Of Garnet Differential Geochronology, Matthew J. Kohn
Geosciences Faculty Publications and Presentations
Rayleigh distillation models are developed to describe theoretical growth zoning of Lu, Hf, Rb, Sr, Sm and Nd in typical garnet crystals from metapelites and metabasites. Effects of diffusion limited transport within the matrix and intracrystalline diffusion are also considered qualitatively. Theoretical zoning profiles show strong depletions of Lu in garnet rims compared to cores, but virtually invariant Hf, Rb, Sr, Sm, and Nd profiles, generally consistent with natural profiles for Lu and Hf and previously published models. Theoretical isochron diagrams for Lu-Hf exhibit distinctive arcuate distributions and high MSWD’s consistent both with Himalayan data, and with expectations that garnet …