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Geology

Missouri University of Science and Technology

2009

Articles 1 - 10 of 10

Full-Text Articles in Physical Sciences and Mathematics

Microbial-Induced Heterogeneity In The Acoustic Properties Of Porous Media, Caroline A. Davis, Laura J. Pyrak-Nolte, Estella A. Atekwana, D. Dale, Werkema, Marisa E. Haugen Nov 2009

Microbial-Induced Heterogeneity In The Acoustic Properties Of Porous Media, Caroline A. Davis, Laura J. Pyrak-Nolte, Estella A. Atekwana, D. Dale, Werkema, Marisa E. Haugen

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

It is not known how biofilms affect seismic wave propagation in porous media. Such knowledge is critical for assessing the utility of seismic techniques for imaging biofilm development and their effects in field settings. Acoustic wave data were acquired over a two-dimensional region of a microbial-stimulated sand column and an unstimulated sand column. The acoustic signals from the unstimulated column were relatively uniform over the 2D scan region. The data from the microbial-stimulated column exhibited a high degree of spatial heterogeneity in the acoustic wave amplitude, with some regions exhibiting significant increases in attenuation while others exhibited decreases. Environmental scanning …

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Apparent Weekly And Daily Earthquake Periodicities In The Western United States, Ali Hadi Atef, Kelly H. Liu, Stephen S. Gao Aug 2009

Apparent Weekly And Daily Earthquake Periodicities In The Western United States, Ali Hadi Atef, Kelly H. Liu, Stephen S. Gao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Analysis of apparent seismicity rate (ASR) using magnitude ≥1 earthquakes located in the western United States confirmed the existence of prominent spectral peaks with periods of 1 and 7 days. The number of recorded earthquakes on Sundays for the duration of 1963-2008 is about 5% higher than that on weekdays, and, more significantly, there is a 9% increase of ASR in the early morning compared with that in the middle of the days. Significant similarities in the spatial distributions of the weekly and daily variations suggest that the two types of variations have the same sources and both originate from …

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Temporal Geophysical Signatures From Contaminant-Mass Remediation, Vukenkeng Che-Alota, Estella A. Atekwana, Eliot A. Atekwana, William August Sauck, D. Dale Werkema Jul 2009

Temporal Geophysical Signatures From Contaminant-Mass Remediation, Vukenkeng Che-Alota, Estella A. Atekwana, Eliot A. Atekwana, William August Sauck, D. Dale Werkema

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We have previously documented changes in bulk electrical conductivity, self-potential (SP), and ground-penetrating-radar (GPR) reflections in a field setting caused by biogeochemical transformations of hydrocarbon-contaminated media. These transformations are associated with hydrocarbon biodegradation. The results of surface geophysical surveys acquired in 1996, 2003, and 2007 document changes in geophysical signatures associated with removing hydrocarbon mass in the contaminated zone. Initial investigations in 1996 showed that relative to background, the contaminated area was characterized by higher bulk electrical conductivity, positive SP anomaly, and attenuated GPR reflections. Repeated surveys in 2003 and 2007 over the contaminated area showed that in 2007, the …

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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 Feb 2009

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 …

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Significant Seismic Anisotropy Beneath The Southern Lhasa Terrane, Tibetan Plateau, Stephen S. Gao, Kelly H. Liu Feb 2009

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 …

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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 Jan 2009

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 …

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Formation Of Iron-Rimmed Sandstone Nodules On Earth; Terrestrial Analogue For The Formation Of Martian Blueberries?, Katherine Charlotte Muller Jan 2009

Formation Of Iron-Rimmed Sandstone Nodules On Earth; Terrestrial Analogue For The Formation Of Martian Blueberries?, Katherine Charlotte Muller

Masters Theses

"NASA's twin Mars Exploration Rovers, MER, Spirit and Opportunity, have identified numerous geologic features that hint at a watery past on Mars noted in Malik, 2004. Prominent among these features are the "Martian Blueberries" that occur as spherical hematite (Fe₂O₃) nodules. Hematite formation is facilitated by the presence of water, although there are presently no known sources of free liquid water on Mars. Chan et al., 2004 states that these "blueberries" are also similar to nodules found in the Jurassic aged Navajo Sandstone in Utah. An understanding of the processes controlling the formation of the Utah nodules may thus be …

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Environmental Geochemistry Of Metal Contaminated Sediments From The Big River System Of Southeastern Missouri, Helen Carrie Bender Jan 2009

Environmental Geochemistry Of Metal Contaminated Sediments From The Big River System Of Southeastern Missouri, Helen Carrie Bender

Masters Theses

"Geochemical analysis of stream sediments from the Big River Watershed of southeastern Missouri indicates that they contain elevated concentrations of contaminant metals such as Pb. Zn, Cu. Co, Ni and Cd. The elevated concentrations are derived from natural exposures of metal enriched strata and the numerous mine tailings piles and water seeps created as a result of about 300 years of lead-zinc mining in the “Old Lead Belt”. Galena (PbS), sphalerite (ZnS), and pyrite (FeS2) are the primary sulfides found in the tailings piles and Scanning Electron Microscopy analysis of individual metallic sediment particles collected at intervals downstream …

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Investigating The Impact Of Microbial Interactions With Geologic Media On Geophysical Properties, Caroline A. Davis Jan 2009

Investigating The Impact Of Microbial Interactions With Geologic Media On Geophysical Properties, Caroline A. Davis

Doctoral Dissertations

"The goals of this study were to investigate the effect of: (1) microbial metabolic byproducts, microbial growth, and biofilm formation on the low frequency electrical properties of porous media, (2) biofilm formation on acoustic wave properties, and (3) the natural electrical (self-potential) signatures associated with an in-situ biological permeable reactive barrier (PRB). The results suggest: (1) increases in electrolytic conductivity are consistent with increased concentrations of organic acids and biosurfactants; (2) mineral weathering promoted by organic acids causes increases in electrolytic conductivity, concomitant with increases in major cation concentrations; (3) interfacial conductivity generally parallels microbial cell concentrations and biofilm formation; …

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The Cretaceous-Paleogene Transition In The Northern Mississippi Embayment, S.E. Missouri: Palynology, Micropaleontology, And Evidence Of A Mega-Tsunami Deposit, Tambra L. Eifert Jan 2009

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 …

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