Geology Commons^™

Spring-Block Models Of Earthquake Dynamics, Ashley E. Mccall

All Graduate Theses, Dissertations, and Other Capstone Projects

In this paper, the dynamics of spring-block models are studied. A brief overview of the history of spring-block models relating to earthquakes is presented, along with the development of friction laws. Several mathematical topics relating to dynamical systems are also discussed. We consider two spring-block models; one with Dieterich-Ruina rate and state dependent friction and another with a modified Dieterich-Ruina style friction. For each system, the qualitative behavior and numerical solutions are presented. In the first case, we find that the system undergoes a Hopf bifurcation from a stationary solution to a periodic orbit, and eventually transitions to chaos. In …

2d And 3d Imaging Of The Metamorphic Carbonates At Omalos Plateau/Polje, Crete, Greece By Employing Independent And Joint Inversion On Resistivity And Seismic Data, Hamdan Ali Hamdan Dr, Nikos Economou, Giorgos Kritikakis, Nikos Andronikidis, Emmanuil Manoutsoglou, Antonis Vafidis, Pangratis Pangratis, Georgina Apostolidou

International Journal of Speleology

A geophysical survey carried out at Omalos plateau in Chania, Western Crete, Greece employed seismic as well as electrical tomography methods in order to image karstic structures and the metamorphic carbonates (Tripali unit and Plattenkalk group) which are covered by post-Mesozoic deposits (terra rossa, clays, sands and gravels). The geoelectrical sections image the metamorphic carbonates which exhibit a highly irregular relief. At the central part of the plateau the thickness of post-Mesozoic deposits (terra rossa, clays, sands and gravels) ranges from 40-130 m. A 3D resistivity image was generated by inverting resistivity data collected on a grid to the south …

Gypsum-Carbonate Speleothems From Cueva De Las Espadas (Naica Mine, Mexico): Mineralogy And Palaeohydrogeological Implications, Fernando Gázquez, Jose Maria Calaforra, Paolo Forti, Fernando Rull, Jesús Martínez-Frías

International Journal of Speleology

Some of the most outstanding hypogenic gypsum speleothems worldwide have been recently discovered in the Naica mines. The Cueva de las Espadas (Swords Cave), which lies at 120 m depth, hosts a rare type of speleothem called “espada” (“sword”). This study contributes to the understanding of the mineralogical composition of these singular speleothems, by means of their examination using micro-Raman spectroscopy, FT-IR spectroscopy and EDX microprobe. Our data revealed a complex mineralogy comprising a high-purity selenite core covered by several layers of calcite, aragonite and gypsum. Solid inclusions of polymetallic oxides (Mn-Pb-Zn) and graphite were also detected. The position of …

Petrographic And Isotopic Evidence For Late-Stage Processes In Sulfuric Acid Caves Of The Guadalupe Mountains, New Mexico, Usa, Margaret V. Palmer, Arthur N. Palmer

International Journal of Speleology

Caves of the Guadalupe Mountains have experienced many modifications since their final phase of sulfuric acid speleogenesis several million years ago. Petrographic and geochemical data reveal details of the change from H₂SO₄ to CO₂-dominated reactions. The H₂SO₄ dissolution front acquired a coating of replacement gypsum with local pockets of anhydrite and by-products of altered clay, including Fe-Mn oxides. Alteration of bedrock beneath the gypsum produced a white micritized rind with small negative shifts in δ¹³C and δ¹⁸O. Solution basins contain records of the earliest post-speleogenetic processes: corroded bedrock, …

Provenance And Geological Significance Of Red Mud And Other Clastic Sediments Of The Mugnano Cave (Montagnola Senese, Italy), Francesco Iacoviello, Ivan Martini

International Journal of Speleology

The Mugnano cave is characterized by a thick clastic sedimentary fill showing a great variability of sedimentary facies, ranging from clay to coarse-grained sand deposits. This paper deals with combined sedimentological and mineralogical (XRD and SEM) studies of these sediments and bedrock insoluble residues in order to understand the origin and geological significance of cave deposits, with particular attention to red mud sediments, often considered as the residue of host rock dissolution. Three different sedimentary facies were recognized: i) YS, yellow sand with occasionally shell fragments, testifying the arrival of sediments from the surrounding landscape; ii) RS, red laminated mud; …

Mantle Flow And Lithosphere-Asthenosphere Coupling Beneath The Southwestern Edge Of The North American Craton: Constraints From Shear-Wave Splitting Measurements, Hesham A. Refayee

Doctoral Dissertations

"High-quality broadband seismic data recorded by the USArray and other stations in the southwestern United States provide a unique opportunity to test different models of anisotropy-forming mechanisms in the vicinity of a cratonic edge. Systematic spatial variations of anisotropic characteristics are revealed by 3027 pairs of splitting parameters measured at 547 broadband seismic stations. The western and southern edges of the North American craton show edge-parallel fast directions with larger-than-normal splitting times, and the continental interior is characterized by smaller splitting times spatially consistent fast directions that are mostly parallel to the absolute plate motion direction of North America. Except …

Plate Kinematics Of The Afro-Arabian Rift System With An Emphasis On The Afar Depression, Helen Carrie Bottenberg

Doctoral Dissertations

This work utilizes the Four-Dimensional Plates (4DPlates) software, and Differential Interferometric Synthetic Aperture Radar (DInSAR) to examine plate-scale, regional-scale and local-scale kinematics of the Afro-Arabian Rift System with emphasis on the Afar Depression in Ethiopia. First, the 4DPlates is used to restore the Red Sea, the Gulf of Aden, the Afar Depression and the Main Ethiopian Rift to development of a new model that adopts two poles of rotation for Arabia. Second, the 4DPlates is used to model regional-scale and local-scale kinematics within the Afar Depression. Most plate reconstruction models of the Afro-Arabian Rift System relies on considering the Afar …

The Reduction Of Storm Surge By Vegetation Canopies: Three-Dimensional Simulations, Y. Peter Sheng, Andrew Lapetina, Gangfeng Ma

Civil & Environmental Engineering Faculty Publications

Significant buffering of storm surges by vegetation canopies has been suggested by limited observations and simple numerical studies, particularly following recent Hurricanes Katrina, Rita, and Wilma. Here we simulate storm surge and inundation over idealized topographies using a three-dimensional vegetation-resolving storm surge model coupled to a shallow water wave model and show that a sufficiently wide and tall vegetation canopy reduces inundation on land by 5 to 40 percent, depending upon various storm and canopy parameters. Effectiveness of the vegetation in dissipating storm surge and inundation depends on the intensity and forward speed of the hurricane, as well as the …

Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner

OES Faculty Publications

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and sub-thermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. …

Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt

OES Faculty Publications

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little …

Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz

OES Faculty Publications

Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene hydrographic variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24° 24.70' N, 83° 13.14' W, 198 m deep) to reconstruct a high-resolution (~25 yr/sample) early to mid Holocene record of sea surface temperature and δ¹⁸O_SW)(a …

New Methods For The Discovery And Characterization Of Lunar Lava Tubes Using Lunar Reconnaissance Orbiter Data, Jonathan Arthur Meyer

Open Access Theses & Dissertations

Lava tubes have the potential to serve as a sustainable solution to long-term lunar habitation by providing protection from radiation and micrometeorite bombardment while potentially providing resources in the form of trapped water ice. They also pose compelling science targets in their own right. While the potential benefits of utilizing lunar lava tubes is clear, their discovery is less straightforward. Formation processes for lava tubes do not always result in a surface expression, making their discovery using remotely sensed imagery difficult. Furthermore, there is the potential for lava tubes to be covered by secondary lava flows, impact ejecta, or other …

Vertical Deformation Along The San Andreas Fault, Garrett Thornton

Open Access Theses & Dissertations

There have been numerous M 6+ earthquakes along the San Andreas Fault System (SAFS) (Schwartz et al., 1984) (Figure. 1.1) in the historical past. These rupture events have created millions of dollars worth of damage, and have been responsible for multiple lives lost. An improved understanding of the motions and crustal characteristics along the SAFS can lead to better hazard mitigation (Bakun et al., 2005). Horizontal crustal motions of the SAFS have been widely studied and applied to seismic hazard models (WGCEP, 2007), however vertical motions are not often utilized due to their complicated origin and sometimes large uncertainties. This …

Seismic Reflection Study Of The East Potrillo Fault, Southwestern Dona Ana County, New Mexico, Shane Alan Carley

Open Access Theses & Dissertations

The East Potrillo Mountains are located just north of the U.S.-Mexico border in southwestern Dona Ana County, New Mexico. Laramide and Rio Grande rift deformation has formed low-angle and high-angle Tertiary normal faults that are exposed in the area. Along the east flank of the range is the East Potrillo Fault identified on the surface as a north-striking scarp. Fault scarps associated with the East Potrillo Fault have been dated using slope degradation models and they range between 56 ka and 377 ka in age. Offset of geomorphic surfaces interpreted to be tectonic terraces records at least four earthquakes over …

Structural Analysis Of The Central Ibex Hills, Death Valley, California, Oscar Esparza

Open Access Theses & Dissertations

The Ibex Hills, in southern Death Valley, California, are composed mainly of Late Proterozoic sedimentary rocks overlying middle Proterozoic basement that are complexly deformed by Mesozoic contractional structures overprinted by Neogene extensional/transtensional structures. Detail mapping of the Ibex Hills reveals evidence of several deformational events. Brittle deformation of both extensional and strike-slip origin are recognized throughout the mapped area, but the main structure identified is a low angle fault at the base of the Noonday Dolomite, Sentinel Peak member, herein called the Noonday Fault. This low angle fault is dipping toward the east-northeast and has a curved geometry that resembles …

Phreatomagmatic Activity On The Moon: Possibility Of Pseudocraters At Mare Frigoris, Jose Humberto Garcia

Open Access Theses & Dissertations

The discovery of water on the Moon raises the possibility that lava-water, or phreatomagmatic, interactions have occurred on the lunar surface in the past. Such interactions may have formed pseudocraters, crater-like landforms that result from steam explosions that occur when lava flows come in contact with surface or near-surface water or ice. We present a study of Mare Frigoris, a volcanic plain just north of the Mare Imbrium impact basin on the Moon. Clusters of irregular, circular features on the basaltic lava flows in this area resemble pseudocrater fields in Iceland, and they are located in a region with inferred …

Evaluating Hydrocarbon Source Rock For Unconventional Shale Oil Play From Seismic And Well Log Data; Kingak Shale, North Slope, Alaska, Sarah Elisabeth Leedberg

Open Access Theses & Dissertations

It has been proposed that Acoustic impedance (AI) responses can be used to estimate total organic carbon (TOC) within thick, clay rich shale. The purpose of this work is to evaluate the effectiveness of the AI inversion technique, and establish a methodology that can be applied to other basins. The Kingak Formation (lower Jurassic to early Cretaceous), located on the North Slope of Alaska, has been extensively evaluated for its unconventional potential. The Kingak is shale and is known to have greater than 30 percent clay. Because clay has ductile properties it makes it difficult to stimulate a well through …

Constraints On The Structure Of The Border Ranges Fault System, South-Central Alaska From Integrated 3d Inversion Of Gravity/Magnetic Data, Niti Mankhemthong

Open Access Theses & Dissertations

I use updated gravity data, available aeromagnetic data, and other geophysical information as constraints to develop 2D and 3D structural models of density and magnetic susceptibility to better locate and determine the shape of the Border Ranges fault system (BRFS), the Border Range ultramafic and mafic assemblages and other forearc-arc boundary structures in south-central Alaska, that have previously been studied in only limited detail. There are three geophysical research projects that form the chapters of the dissertation. First, I estimated near-surface density variations in the central Kenai Peninsula based on the adaptation of the Nettleton (1939)-Parasnis (1952) method using Tarantola …

Numerical Modeling Of Tectonics And Fault Activity Of Icy Satellites, John Olgin

Open Access Theses & Dissertations

Enceladus, one of the satellites of Saturn, exhibits evidence of recent fault activity, which may be due to gravitational fluctuations, or tidal stresses, generated by its orbit around Saturn. Recent Cassini spacecraft observations of Enceladus reveal water-ice plume activity at the south polar region, originating from locations that correlate with four geologically young, linear fracture-like features, named the "tiger stripes". It is the goal of this investigation to determine the ideal geophysical and geological factors (e.g., fault depths, frictional coefficients, ice layer thickness, ocean layer thickness, tidal stress sources) that support fault activity on Enceladus. The core of this work …

Isotope Geochemistry And Geochronology Of Lavas From The Line Islands Chain, Central Pacific Basin: Insight Into The Origin Of The Line Islands, Lauren Storm

Open Access Theses & Dissertations

Geochemical compositions of melts produced in the Earth's mantle provide key data for understanding Earth's internal structure. Particularly, the compositions of unusually large outpourings of basaltic lavas in large igneous provinces involve substantial source volumes, thereby contributing to our understanding of mantle structure and dynamics. Although the origin of such lavas remains enigmatic, geochemically they may originate from Earth's oldest and deepest mantle reservoir, transported by a mantle plume or by entrainment in passive upwelling beneath a fast spreading center. The Pacific Ocean basin hosts several large igneous provinces that formed near a triple junction of three oceanic plates, and …

Grain Size Distribution With Geomorphology On Gypsum Dunes In The White Sands Erg, White Sands National Monument, New Mexico, Slade Jones

Open Access Theses & Dissertations

In order to examine grain size distribution over dunes at the White Sands dune field, 1214 geolocated surficial samples were collected and analyzed by laser diffraction. Local variations in dunes such as neighboring interdune types and the presence of vegetation, deflation features, and granule ripples on the dunes were noted. This study indicates that recrystallization of gypsum and the generation of fresh sediments is occurring in significant quantities within interdunes, providing both high and low anomalies in grain size distribution through much of the central portion of the dune field. Other local variations as previously mentioned such as scour surfaces …

Characterization Of Thrust Faults On The Moon Using Fault Dynamics And 3d Visualizations, Jaclyn Danielle Clark

Open Access Theses & Dissertations

Many small, lobate scarps, interpreted to be the surface traces of thrust faults, have been found all over Earth's moon by previous researchers. Fault dynamical calculations, assuming an initially completely molten Moon, have shown that these scarps can form due to compressional stresses that accumulate over time as the result of large-scale contraction of the Moon as it cooled. With high-resolution images from the Lunar Reconnaissance Orbiter Camera (LROC), previously undetected lobate scarps can be found globally and viewed at high resolution. By investigating these fault scarps, we can determine better constraints on the amount of crustal shortening and improve …

A New Phase Speciation Leaching Procedure For The Determination Of Metals In Oxic And Anoxic Sediments, Brandon R. Gipson

OES Theses and Dissertations

Toxic trace elements such as cadmium, lead, chromium, and arsenic released by human activities can accumulate in marine and estuarine sediments, where these metals are often sequestered until local environmental changes (e.g., redox, salinity, and/or pH) allow these elements to be reintroduced into the food web. In order to assess the extent of toxic trace element contamination in sediment, numerous leaching schemes have been developed that separate sediment-bound trace metals into operationally defined geochemical phases. These "phase speciation" leaching schemes are typically designed with the purpose of being used on either oxic or anoxic sediments. However, natural sediments often contain …

Stability Of Rock Slopes Along Raidah Escarpment Road, Asir Area, Kingdom Of Saudi Arabia, Ahmed M. Youssef, Norbert H. Maerz, Abdulla A. Al-Otaibi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Raidah Escarpment road is located north west of Abha city, Asir region, Kingdom of Saudi Arabia. This escarpment road represents an important corridor in the area which connects different villages and tourist resorts with each other. The total length of this road section is about 9 km which passes through a highly mountainous area. The road also passes through areas of different geological hazards (rock, debris flow, soil, and weathered zones). The different environmental factors (e.g. intensive rainy summer), variable geological and structural elements (weak rocks, slide debris weak soils, shear zones, and faults) difficult road characteristics (narrow roads …

Natural And Anthropogenic Influences On The Morphodynamics Of Sandy And Mixed Sand And Gravel Beaches, Tiffany Roberts

USF Tampa Graduate Theses and Dissertations

Beaches and coastal environments are dynamic, constantly shaped and reshaped by natural processes and anthropogenic modifications. The morphodynamics and influence of natural and anthropogenic factors of two different coasts at various temporal and spatial scales are discussed.

To quantify the performance of several beach nourishment projects at annual temporal and kilometer spatial scales on three adjacent microtidal low-wave energy barrier islands in west-central Florida, a total of 5,200 beach and nearshore-profiles spaced at 300 m were surveyed monthly to bi-monthly from 2006-2010. Beach nourishment performance is most significantly influenced by the interruption of longshore sediment transport by complex tidal-inlet processes. …

Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall

USF Tampa Graduate Theses and Dissertations

Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly …

Something Is Askew In Florida's Water: Arguing For A Better Descriptive Statistic For Positively Skewed Water-Quality Data, Amie October West

USF Tampa Graduate Theses and Dissertations

ABSTRACT

It may be of no surprise that water quality data is right-skewed, but what appears to be overlooked by some is that the arithmetic mean and standard deviation most often fail as measures of central tendency in skewed data. When using the arithmetic mean and arithmetic standard deviation with nutrient data, one standard deviation about the arithmetic mean can capture nearly all of the data and extend into negative values. Representing nutrient data this way can be misleading to viewers who are using the statistics, and making assumptions, to understand the characteristics of those waters. Through an in-depth statistical …

Landsat Remote Sensing Data As An Alternative Approach For Geological Mapping In Tanzania: A Case Study In The Rungwe Volcanic Province, South-Western Tanzania, E. E. Mshiu

Tanzania Journal of Science

Rungwe Volcanic Province (RVP) is mostly covered by extrusive rocks that overlain the Precambrian basement. The use of Landsat data in this area has revealed the need of effective use of these data in geological mapping programs in Tanzania. Landsat band ratios 5/1, 3/7, 5/7 and 5/4 as well as R: G: B composite images 7:4:1, 7:5:4, 1/3:5/7:3/5 and 4/5:6/7:4/6 played an important role in identifying different rock types in the study area. Ratio images managed clearly to distinguish between mafic and felsic rocks whereby two lithological blocks were identified, Block 1 covers a combination of intrusive and metamorphic rocks …

Contact Metamorphism In The Supracrustal Rocks Of The Sukumaland Greenstone Belt In The North West Tanzania, N. Boniface

Tanzania Journal of Science

Biotite-granite intrusions in meta-ironstones at Geita Hills and the Bukoli alkali-granite intrusion in metabasites at Mawemeru area produced heat that baked the respective country rocks through epidote-amphibolite- to amphibolite-facies. Critical and informative mineral assemblages in the metairostones of Geita Hills are garnet-grunerite-epidote-quartz and garnetferrogedrite- biotite-quartz and in the metabasites of Mawemeru is ferrotschermakite-(Naplagioclase)- quartz. Peak temperatures ranging between 438°C and 544°C were calculated from the above mineral assemblages and a pressure not exceeding 3 kbar was inferred to from the composition of magnesium-iron amphiboles (grunerite with XFe ratio of 0.83, i.e. Gru83). Hornfels textures in the metaironstones are suggested by …

Petrography And Geochemistry Of Mafic Granulites Of The Ubendian Belt: Contribution To Insights Into The Lower Continental Crust Of The Paleoproterozoic, N. Boniface

Tanzania Journal of Science

Mafic granulites of the Ubendian Belt have geochemical signature, trace and REE patterns, similar to that of the lower continental crustal rocks. A SHRIMP U-Pb single zircon date at 1977±40 Ma indicates that these rocks belong to the Paleoproterozoic Ubendian orogenic cycle, which was followed by the Mesoproterozoic tectonic disturbance that contributed to their exhumation. Orthopyroxene, clinopyroxene, garnet, hornblende, plagioclase and quartz is a frequent mineral assemblage for the mafic granulites of the Ubendian Belt, and garnet frequently form corona between plagioclase and clinopyroxene. Geothermobarometric calculations have revealed the equilibration of these rocks at a temperature range between 650 and …