Geology Commons^™

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 …

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 …

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 …

Documenting The Origin Of Compositional Diversity Of Subduction Zone Magmatism, Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy) Using In Situ Plagioclase Data, Rachel Hunt

All Master's Theses

Processes that generate magma compositional diversity are important to document because composition affects degree of explosivity, which impacts hazard mitigation. Magnesium to silicon rich magmas are produced by processes such as magma recharge, assimilation, and fractional crystallization (RAFC) that occur in subvolcanic magma chamber(s). This study evaluates how magma chamber processes contribute to compositional diversity at Alicudi Volcano, Italy. Analytical and petrographic data from ten samples that span the subaerial history include whole rock major and trace elements and strontium/neodymium isotopes, and plagioclase textural types, major and trace elements, and strontium isotopes; numerical modeling was also conducted. Integration of these …

Scientific Drilling Of Speleothems – A Technical Note, Christoph Spötl, David Mattey

International Journal of Speleology

This short article provides detailed descriptions of custom-made and commercially available hand-held drilling gear and options for water-flushing units specifically designed to obtained good-quality core material from speleothems even in remote cave regions. We use small-diameter (6-7 mm) diamond drill bits to obtain aliquots of calcite (as little as a few hundreds of milligram) from the interior of the basal part of in-situ stalagmites. These small cores are used to date the onset of stalagmite growth and occasionally to obtain other compositional information. Larger diameter drill bits produce cores 25-32 mm in diameter and up to 1.3 m in length …

In Defense Of A Fluctuating-Interface, Particle-Accretion Origin Of Folia, Donald G. Davis

International Journal of Speleology

Two recent papers have proposed radically different modes of origin for cave folia. Audra et al. (2009) propose subaqueous origin of carbonate folia via hypogenic CO₂ bubble trapping, with concurrent condensation-corrosion and evaporative precipitation within individual folia gas pockets. Queen (2009) proposes that at least some folia are analogous to suboceanic tufa-tower "flanges" and may result from subaqueous freshwater mixing into a briny environment. The purpose of this paper is to show that neither of these mechanisms can be the fundamental process responsible for folia morphology in cave deposits, and that accretion from adherent particles at fluctuating interfaces is …

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 …

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 …

Diagenesis Of A Drapery Speleothem From Castañar Cave: From Dissolution To Dolomitization, Andrea Martín-Pérez, Rebeca Martín-García, Ana M. Alonso-Zarza

International Journal of Speleology

A drapery speleothem (DRA-1) from Castañar Cave in Spain was subjected to a detailed petrographical study in order to identify its primary and diagenetic features. The drapery’s present day characteristics are the result of the combined effects of the primary and diagenetic processes that DRA-1 underwent. Its primary minerals are calcite, aragonite and huntite. Calcite is the main constituent of the speleothem, whereas aragonite forms as frostwork over the calcite. Huntite is the main mineral of moonmilk which covers the tips of aragonite. These primary minerals have undergone a set of diagenetic processes, which include: 1) partial dissolution or corrosion …

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; …

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, …

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 …

Evaluation Of Single-Step Steam Pyrolysis-Activated Carbons From Lesotho Agro-Forestry Residues, I. Hapazari, V. Ntuli, W. Parawira

Tanzania Journal of Science

Activated carbon has been widely used worldwide as an effective filtration or adsorption material for removing biological and chemical contaminants from drinking water. The potential of producing activated carbon (AC) from local agroforestry residues by single-step steam pyrolysis processes was investigated. The research aims to promote innovative use of local raw materials and relatively low-cost techniques in production of activated carbon. Four varieties of activated carbons from four different agroforestry residues, pine (Pinus contorta) cones (PC), Abies (Abies cilicica) seeds (AS), maple (Acer ginnala) seeds (MS) and peach (Prunus persica) stones (PS), were prepared and evaluated. The ACs were evaluated …

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 …

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 …

Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, Beth Pratt-Sitaula, Douglas W. Burbank, Arjun M. Heimsath, Neil F. Humphrey, Michael Oskin, Jaakko Putkonen

All Faculty Scholarship for the College of the Sciences

Differences in the timing of glacial advances, which are commonly attributed to climatic changes, can be due to variations in valley topography. Cosmogenic 10Be dates from 24 glacial moraine boulders in 5 valleys define two age populations, late-glacial and early Holocene. Moraine ages correlate with paleoglacier valley hypsometries. Moraines in valleys with lower maximum altitudes date to the lateglacial, whereas those in valleys with higher maximum altitudes are early Holocene. Two valleys with similar equilibrium-line altitudes (ELAs), but contrasting ages, are < 5 km apart and share the same aspect, such that spatial differences in climate can be excluded. A glacial mass-balance cellular automata model of these two neighboring valleys predicts that change from a cooler-drier to warmer-wetter climate (as at the Holocene onset) would lead to the glacier in the higher altitude catchment advancing, while the lower one retreats or disappears, even though the ELA only shifted by ~120 m.