Physical Sciences and Mathematics Commons^™

Geophysical Signatures Of Disseminated Iron Minerals: A Proxy For Understanding Subsurface Biophysicochemical Processes, Gamal Z. Abdel Aal, Estella A. Atekwana, Andre Revil

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Previous studies have linked biogeophysical signatures to the presence of iron minerals resulting from distinct biophysicochemical processes. Utilizing geophysical methods as a proxy of such biophysicochemical processes requires an understanding of the geophysical signature of the different iron minerals. Laboratory experiments were conducted to investigate the complex conductivity and magnetic susceptibility signatures of five iron minerals disseminated in saturated porous media under variable iron mineral content and grain size. Both pyrite and magnetite show high quadrature and inphase conductivities compared to hematite, goethite, and siderite, whereas magnetite was the highly magnetic mineral dominating the magnetic susceptibility measurements. The quadrature conductivity …

Mantle Transition Zone Discontinuities Beneath The Contiguous United States, Stephen S. Gao, Kelly H. Liu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Using over 310,000 high-quality radial receiver functions recorded by the USArray and other seismic stations in the contiguous United States, the depths of the 410 km and 660 km discontinuities (d410 and d660) are mapped in over 1,000 consecutive overlapping circles with a radius of 1⁰. The average mantle transition zone (MTZ) thickness for both the western and central/eastern U.S. is within 3 km from the global average of 250 km, suggesting an overall normal MTZ temperature beneath both areas. The Pacific Coast Ranges and the southern Basin and Range Province are underlain by a depressed d410, indicating higher-than-normal temperature …

Seismic Imaging Of Mantle Transition Zone Discontinuities Beneath The Northern Red Sea And Adjacent Areas, A. A. Mohamed, Stephen S. Gao, A. A. Elsheikh, Kelly H. Liu, Youqiang Yu, R. E. Fat-Helbary

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The dramatic asymmetry in terms of surface elevation, Cenozoic volcanisms and earthquake activity across the Red Sea is an enigmatic issue in global tectonics, partially due to the unavailability of broad-band seismic data on the African Plate adjacent to the Red Sea. Here, we report the first comprehensive image of the mantle transition zone (MTZ) discontinuities using data from the Egyptian National Seismic Network, and compare the resulting depths of the 410 and 660-km discontinuities with those observed on the Arabian side. Our results show that when a standard earth model is used for time-to-depth conversion, the resulting depth of …

Mechanistic Models Of Biofilm Growth In Porous Media, Priyank Jaiswal, K. Fathiya Al-Hadrami, Estella A. Atekwana, Eliot A. Atekwana

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Nondestructive acoustics methods can be used to monitor in situ biofilm growth in porous media. In practice, however, acoustic methods remain underutilized due to the lack of models that can translate acoustic data into rock properties in the context of biofilm. In this paper we present mechanistic models of biofilm growth in porous media. The models are used to quantitatively interpret arrival times and amplitudes recorded in the 29 day long Davis et al. (2010) physical scale biostimulation experiment in terms of biofilm morphologies and saturation. The model pivots on addressing the sediment elastic behavior using the lower Hashin-Shtrikman bounds …

The Capacity Of Hydrous Fluids To Transport And Fractionate Incompatible Elements And Metals Within The Earth's Mantle, John Adam, Marek Locmelis, Juan Carlos Afonso, Tracy Rushmer, Marco L. Fiorentini

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Both silicate melts and aqueous fluids are thought to play critical roles in the chemical differentiation of the Earth's crust and mantle. Yet their relative effects are poorly constrained. We have addressed this issue by measuring partition coefficients for 50 trace and minor elements in experimentally produced aqueous fluids, coexisting basanite melts, and peridotite minerals. The experiments were conducted at 1.0-4.0 GPa and 950-1200°C in single capsules containing (either 40 or 50 wt %) H₂O and trace element-enriched basanite glass. This allowed run products to be easily identified and analyzed by a combination of electron microprobe and LAM-ICP-MS. …

A Uniform Database Of Teleseismic Shear Wave Splitting Measurements For The Western And Central United States, Kelly H. Liu, Ahmed Elsheikh, Awas Lemnifi, Uranbaigal Purevsuren, Melissa Ray, Hesham Refayee, Bin B. Yang, Youqiang Yu, Stephen S. Gao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We present a shear wave splitting (SWS) database for the western and central United States as part of a lasting effort to build a uniform SWS database for the entire North America. The SWS measurements were obtained by minimizing the energy on the transverse component of the PKS, SKKS, and SKS phases. Each of the individual measurements was visually checked to ensure quality. This version of the database contains 16,105 pairs of splitting parameters. The data used to generate the parameters were recorded by 1774 digital broadband seismic stations over the period of 1989-2012, and represented all the available data …

Seismic Anisotropy And Subduction-Induced Mantle Fabrics Beneath The Arabian And Nubian Plates Adjacent To The Red Sea, Ahmed A. Elsheikh, Stephen S. Gao, Kelly H. Liu, Abdelnasser A. Mohamed, Youqiang Yu, Raafat E. Fat-Helbary

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

For most continental areas, the mechanisms leading to mantle fabrics responsible for the observed anisotropy remain ambiguous, partially due to the lack of sufficient spatial coverage of reliable seismological observations. Here we report the first joint analysis of shear-wave splitting measurements obtained at stations on the Arabian and Nubian Plates adjacent to the Red Sea. More than 1100 pairs of high-quality splitting parameters show dominantly N-S fast orientations at all 47 stations and larger-than-normal splitting times beneath the Afro-Arabian Dome (AAD). The uniformly N-S fast orientations and large splitting times up to 1.5 s are inconsistent with significant contributions from …

Peritidal Carbonate Cycles Induced By Carbonate Productivity Variations: A Conceptual Model For An Isolated Early Triassic Greenhouse Platform In South China, Wan Yang, Daniel J. Lehrmann

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is difficult to explain cycles formed in a greenhouse climate when eustasy is minimal. We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou, South China, were formed by hierarchical carbonate productivity variations. Most of the 149 shallowing-upward cycles are typically terminated by flooding over intertidal facies and contain rare supratidal facies and no prolonged subaerial exposure. Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations, which caused variations in benthic sediment productivity in the subtidal carbonate factory. …

Seismic Anisotropy And Mantle Flow Beneath The Northern Great Plains Of North America, Bin B. Yang, Stephen S. Gao, Kelly H. Liu, Ahmed A. Elsheikh, Awad A. Lemnifi, Hesham A. Refayee, Youqiang Yu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A diverse set of tectonic features and the recent availability of high-quality broadband seismic data from the USArray and other stations on the northern Great Plains of North America provide a distinct opportunity to test different anisotropy-forming mechanisms. A total of 4138 pairs of well-defined splitting parameters observed at 445 stations show systematic spatial variations of anisotropic characteristics. Azimuthally invariant fast orientations subparallel to the absolute plate motion (APM) direction are observed at most of the stations on the Superior Craton and the southern Yavapai province, indicating that a single layer of anisotropy with a horizontal axis of symmetry is …

Receiver Function Constraints On Crustal Seismic Velocities And Partial Melting Beneath The Red Sea Rift And Adjacent Regions, Afar Depression, Cory A. Reed, Sattam Almadani, Stephen S. Gao, Ahmed A. Elsheikh, Solomon Cherie, Mohamed G. Abdel Salam, Allison K. Thurmond, Kelly H. Liu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Afar Depression is an ideal locale for the investigation of crustal processes involved in the transition from continental rifting to oceanic spreading. To provide relatively high resolution images of the crust beneath the Red Sea rift (RSR) represented by the Tendaho graben in the Afar Depression, we deployed an array of 18 broadband seismic stations in 2010 and 2011. Stacking of about 2300 receiver functions from the 18 and several nearby stations along the ~200 km long array reveals an average crustal thickness of 22 ± 4 km, ranging from ~17 km near the RSR axis to 30 km …

Spectral Induced Polarization (Sip) Response Of Biodegraded Oil In Porous Media, Gamal Z. Abdel Aal, Estella A. Atekwana

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Laboratory experiments were conducted to investigate the effect of different oil saturation (0.2- 0.8), wetting conditions (water-wet and oil-wet), and the addition of asphaltene on the spectral induced polarization (SIP) response of biodegraded and fresh crude oil in sand columns. In the water-wet case, no significant differences were observed for both the fresh and biodegraded oil and both displayed an increase in the magnitude of the phase (φ) and decrease in the magnitudes of the real (σ′) and imaginary (σ″) conductivity components with increasing oil saturation. In this instance the SIP response is most likely controlled by the conduction and …

Modelling The Subsurface Geomorphology Or An Active Landslide Using Lidar, Norbert H. Maerz

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

No abstract provided.

A Remote Sensing Investigation Of Elevated Sub-Horizontal Topographic Surfaces In The Wichita Mountains, Oklahoma, Liang Xue

Masters Theses

"Multiple elevated horizontal to sub-horizontal topographic surfaces are present in the Wichita Mountains, Oklahoma. Elevated topographic surfaces, developed primarily on granite bedrock with gentle slopes of 0.5 to 7⁰,were investigated using 1) Digital Elevation Models (DEMs) extracted from NAD 27 UTM coordinates, 2) Google Earth imagery, and 3) USGS topographic maps. In the western Wichita Mountains prominent topographic surfaces at elevations of 720 ± 5 m, 685 ± 5 m, and 660 ± 5 m are well preserved on at least four different mountains (e.g., Solder's Peak, King Mt.) and can be correlated with similar surfaces on at least seven …

Pn Anisotropy Tomography Of The Colorado Plateau And Adjacent Areas, Shengyao Cheng

Masters Theses

"The Pn tomography method utilizes seismic waves that refract along the Moho interface to perform inversion in order to investigate velocity anomalies and seismic anisotropy in the uppermost mantle. Results from Pn tomography can provide important information about the composition, temperature, and tectonic processes beneath the study area. Over the past decades, numerous seismic and geologic studies have been conducted in the Colorado Plateau and its adjacent areas to reveal crustal and mantle structures and processes responsible for the diverse surface geological features and tectonic events that have occurred in this area. To investigate lateral variations in the uppermost mantle …

Crustal Thickness And Vp/Vs Beneath The Western United States: Constraints From Stacking Of Receiver Functions, Uranbaigal Purevsuren

Doctoral Dissertations

"This study investigates crustal characteristics beneath the western United States. Crustal parameters, including crustal thickness (H), mean Vp/Vs, and the sharpness of the Moho as quantified by the amplitude of the P-to-S converted phases from the Moho, are measured at a total of 1000 permanent and portable broadband seismic stations using over 150,000 receiver functions recorded between 1988 and 2012. The study area is composed of a diverse set of tectonic provinces formed by a series of tectonic events, and is thus ideal for investigating crustal formation and modification by different tectonic processes. The resulting crustal thickness varies from …

Shear-Wave Splitting And Mantle Deformation Beneath The Western Tibetan Plateau, Melissa Ann Ray

Masters Theses

"The Tibetan Plateau has been an enigma to the scientific community since scientists first began to focus their attention on the area. Numerous studies over the decades were conducted to address how the plateau formed, mostly in the central and eastern portions of the Tibetan Plateau. Many questions still remain regarding the western Tibetan Plateau, and this study will add constraints to the mechanisms which regulated the formation of the plateau.

Data was acquired from over 13,000 measurements from 172 stations covering the western region of the plateau encompassing the Qiangtang Terrane, the Lhasa Terrane, and the Himalayan Orogenic Zone. …

A Receiver Function Study Of Crust Thickness And Composition Beneath The Southwestern United States, Si Wu

Masters Theses

"Over the past decades, the seismic structure of the crust and upper mantle of the southwestern United States was examined using an array of different methods. The structure and composition of crust received special attentions, most due to the hydrocarbon reserves in this area. Here new constraints on crustal evolution and structure models are provide by systematically analyzing 37,402 receiver functions recorded at 234 seismic stations on the southwestern United States. The results reveal that the Transitional Crust is characterized by a thin (29.0±1.0 km) crust, a low Vp/Vs ratio of 1.76±0.016 and a high amplitude (R) of P-to-S converted …

Biomineralization Of Carbonates In Modern Microbial Sediments And Its Implications For Co₂ Sequestration, Varun Gnanaprian Paul

Doctoral Dissertations

"Several bacterial species influence carbonate mineral precipitation by modifying pH, alkalinity, Ca²⁺ activity and by providing nucleation sites for mineralization. Two studies have been undertaken to explore microbial influence in the mineralization of carbonates. In the first study, the ability of sulfate-reducing bacteria (SRB) to induce carbonate mineralization was investigated as a means to enhance mineral sequestration of CO₂. Sulfate-reducing bacteria enriched from hypersaline Storr's Lake, The Bahamas; Lake Estancia, New Mexico; and Great Salt Plains Lake, Oklahoma, were tested in reactors under varying CO₂ concentrations. Carbonate mineral precipitation was achieved only in reactors with Lake Estancia SRB community and …

An Investigation Of Rock Fall And Pore Water Pressure Using Lidar In Highway 63 Rock Cuts, Norbert H. Maerz

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

No abstract provided.

An Investigation Of Contaminant Metal Distribution And Mineral Speciation In The Soil Near The Buick Recycling Division Smelter, Iron County, Missouri, Krista Nicole Rybacki

Masters Theses

"Trace metal contamination studies were conducted near the Buick Resource Recycling Division. This study used sequential extraction, total digestion, X-Ray Diffraction (XRD), and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) to study trace metals in two soil cores. Sequential extraction analysis of the soil cores revealed that lead was associated with either iron or manganese oxides. Zinc and copper were bound to soil components, extracted mainly from organics, sulfides, and clays. Total digestion results compared favorably to the sum of the sequential extraction results for lead, thus validating the sequential extraction methodology. The highest concentration observed for lead was 4,743 parts …

High-Resolution Magnetic Susceptibility Measurements For Investigating Magnetic Mineral Formation During Microbial Mediated Iron Reduction, Estella A. Atekwana, Farag M. Mewafy, Gamal Z. Abdel Aal, D. Dale Werkema, Andre Revil, Lee D. Slater

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Disimilatory iron-reducing bacteria play an important role in the reduction of Fe(hydr)oxides and the production of secondary solid-iron mineral phases that can have magnetic properties. Magnetic susceptibility can therefore play an important role in identifying zones where microbial-mediated iron reduction is occurring. We investigated the magnetic susceptibility variations in a hydrocarbon-contaminated aquifer where methanogenesis and iron reduction are the main biogeochemical processes. Our objectives are to (1) determine the variability of magnetic susceptibility, (2) determine the hydrobiogeochemical controls on the magnetic susceptibility variability, and (3) evaluate the use of magnetic susceptibility as a viable technique for identifying zones where the …

Development Of Structural Basins And Domes On The Sinn El-Kaddab Plateau, Egypt: Insights From In Situ Data And Application Of Moderate Resolution Orbital Imagery Of The Seiyal Fault, Thomas J. Jerris

Masters Theses

"The Seiyal Fault, one of many east-west trending faults located in the Western Desert of Egypt, and associated structural basins and domes are investigated using remote sensing imagery and field studies. Analysis of Shuttle Reconnaissance Topography Mission data, multi-spectral data from the Landsat Thematic Mapper (LM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), the Advanced Spaceborne Thermal Emission and Reflectometer (ASTER) data, and imagery from Google Earth. Band combinations 3-2-1 and 7-4-2 in ETM+ and 3N-2-1 and 7-3-1 in ASTER, and Google Earth provided the most useful images for geologic mapping. The Seiyal Fault is best characterized as a zone …

Precambrian Evolution Of The Salalah Crystalline Basement From Structural Analysis And 40Ar/39Ar Geochronology, Hanadi Abulateef Al-Doukhi

Doctoral Dissertations

"The Salalah Crystalline Basement (SCB) is the largest Precambrian exposure in Oman located on the southern margin of the Arabian Plate at the Arabian Sea shore. This work used remote sensing, detailed structural analysis and the analysis of ten samples using ⁴⁰Ar/³⁹Ar age dating to establish the Precambrian evolution of the SCB by focusing on its central and southwestern parts. This work found that the SCB evolved through four deformational events that shaped its final architecture: (1) Folding and thrusting event that resulted in the emplacement of the Sadh complex atop the Juffa complex. This event resulted …

Seismic Anisotropy And Mantle Flow Beneath Africa And Arabia, Ahmed Abdalla Elsheikh

Doctoral Dissertations

"In spite of numerous studies, the mechanisms for the rifting, uplifting, and volcanism on the African plate remain enigmatic. The most popular hypotheses proposed for explaining these tectonic phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and volcanism of the Cameroon Volcanic Line (CVL) and the Arabian plate. The splitting of P-to-S converted phases at the core-mantle boundary on the receiver side (XKS including PKS, SKKS, and SKS) …