Geology Commons^™

Microstructural Characteristics Of Deformed Quartz Under Non-Steady-State Conditions, Hamidreza Soleymani

Dissertations, Theses, and Capstone Projects

Because of the long timescale of many geological processes (millions of years), it has been traditionally assumed that the existing forces acting on the rocks at deep crustal levels are in equilibrium (i.e., steady-state). An alternative assumption, however, suggests that rocks in the lower crust and upper mantle are continuously evolving and exchanging energy at various time scales. Under the latter assumption (i.e., non-steady-state), certain geologic systems may never attain equilibrium regardless of the length and the time scale of operating geologic events. These two “endpoint” assumptions suggest there is a wide range of geologically reasonable conditions under which rocks …

Bathymetry Based Modeling Of Subaxial Magma Flows Under The Mid-Atlantic Ridge, 0 To 30° N, Adam R. Tjoelker, Neil Van Kanegan, C. Renee Sparks

Summer Research

The study area for this investigation includes the MidAtlantic Ridge (MAR) system from the Equator to 30° north latitude. In its entirety, the MAR system runs from around 87° N to 54° S through roughly the center of the Atlantic Ocean. The width of the Ridge ranges from 1000-1300 km (Liu et al., 2021). After conducting a similar study of the MAR system from the Equator to 30° S latitude, (Detmer et al., 2021 in review), the addition of magmatic modelling in this study enables continued investigation of the MAR’s tectonic fabric and allows us to test our hypotheses for …

Peralkaline Silicic Extrusive Rocks: Magma Genesis, Evolution, Plumbing Systems, And Eruption., Ray Macdonald, John C. White, Harvey E. Belkin

EKU Faculty and Staff Scholarship

Peralkaline silicic extrusive rocks are an important component of the volcanological record. Here we review several aspects of their formation and evolution, including the tectonic settings in which they occur, their main petrological and geochemical features, the magmatic lineages along which they evolve, and the parameters (T, P, fO₂, melt water contents) that control the lineages. Particular attention is paid to the composition of the extraordinary melts formed at the lowest temperatures. Various lines of evidence are presented to explain the silica-gaps in some lineages. The partial melting of continental crust and the role of crustal contamination …

Analyzing Slab Holes In Subduction Zones And Their Impacts Through Numerical Simulations, Taylor M. Arrowood

Theses and Dissertations--Earth and Environmental Sciences

Subduction zones form as higher density oceanic lithosphere is forced beneath an over-riding, lower density, continental or oceanic plate; a process driven by contrasts in buoyancy throughout this system. We seek to explore subduction zones in which the subducting lithosphere is discontinuous after passing through the trench, forming a slab gap. The main research objective is to determine the effect of slab gaps on surface topography in a subduction-related orogen and asthenospheric flow into the mantle wedge using two and three-dimensional numerical mechanical models. We obtain results from 24+ models that suggest a connection between slab gaps/holes and the magnitude …

Structural And Thermochronologic Evidence Of Paleogene-Neogene Faulting And Exhumation Of The Klamath Mountain Province, Taylor C. Team

Cal Poly Humboldt theses and projects

The Klamath Mountains Province (KMP), located at the southern end of the forearc of the Cascadia Subduction Zone, displays a distinct topographic and geologic signature. Compared to the forearc in the north, the KMP comprises Paleozoic-Mesozoic basement rocks with relatively high modern elevation and relief. This study investigates the pattern of rock cooling in the KMP by using thermochronology on plutons exhumed by faults and plutons outside of mapped faults. In this study, I target three regions in the KMP: the Ashland pluton offset by the Siskiyou Summit fault in the northeast KMP, the Grayback pluton in the northwest KMP, …

A Karst Feature Prediction Model For Prince Of Wales Island, Alaska Based On High Resolution Lidar Imagery, Alexander Lyles

Master's Theses or Doctor of Nursing Practice

Investigation into surface karst formation is significant to hazard prediction, hydrogeologic drainage, and land management. Southeast Alaska contains over 600,000 acres of mapped carbonate bedrock, and some of the fastest recorded karst dissolution in the world. The objectives of this study are to develop and compare multiple semi-automated models to map and delineate karst features from bare-earth LiDAR imagery using ArcGIS Desktop 10.7, and to apply a preliminary geostatistical analysis of sinkhole morphometric parameters to highlight potential spatial patterns of karst evolution on Prince of Wales Island, Alaska. A semi-automated approach of mapping karst features provides a dataset that minimizes …

The Effects Of Heterogeneities And Syn-Deformational Partial Melting On Rock Strength Evolution And Melt Migration, Nicole Wagner

Williams Honors College, Honors Research Projects

In nature, the segregation of granitic melts at the source may be controlled by fabric and compositional heterogeneities in the source rock, such as foliation and lineation. To investigate the influence of foliation/lineation orientation and composition on rock strength and melt interconnectivity, I performed a series of experiments on cores of a fine-grained gneiss (Gneiss Minuti) and a fine-grained muscovite-bearing quartzite (Moine Thrust quartzite). These rocks were cored at six primary orientations parallel, 45 degrees, and perpendicular to the foliation and lineation and were deformed at a constant temperature of 900°C, pressure of ~2 GPa, and strain rate of ~10-6/s …

Petrogenesis And Tectonic Implications Of Cordierite-Orthoamphibole Gneisses (Cog) In The Nw Wyoming Province, Brianna K. Crenshaw Ms

Graduate Student Theses, Dissertations, & Professional Papers

Studying cordierite orthoamphibole gneisses (COG) from five different mountain ranges across the Montana Metasedimentary Terrane (MMT) of the Wyoming Province offers a unique opportunity to elucidate the enigmatic origins and petrogenesis of the lithology in addition to gaining a further understanding of Precambrian crustal assembly processes. Geochemical analyses suggest that COG originates from a basalt that underwent metasomatic alteration, likely via seawater, prior to metamorphism. Moreover, COG is considered to represent oceanic crust that was part of the epicontinental sea adjacent to the Wyoming Province before collision with the Medicine Hat Block. Field observations of associated lithologies such as marbles, …

Analysis Of Water Concentration Formed Within Deformed Synthetic Quartz Crystals, Andrew Steward

Williams Honors College, Honors Research Projects

Analyzing the strength of synthetic quartz is essential to understanding the strength of natural milky quartz, which likely controls the strength of Earth’s continental crust. Synthetic quartz is sometimes used for deformation experiments because it has a homogenous water distribution unlike natural milky quartz. The purpose of this study is to determine if annealing synthetic quartz at T = 600°C will convert the water in synthetic quartz to free water, like milky quartz, but with little water loss. Following two annealing experiments at Texas A&M University, I performed four annealing experiments to measure the water content of five synthetic quartz …

Structural Analysis And Interpretation Of Deformation Along The Keweenaw Fault System West Of Lake Gratiot, Keweenaw County, Michigan, Sophie A. Mueller

Dissertations, Master's Theses and Master's Reports

The Keweenaw fault is perhaps the most significant fault associated with the Midcontinent Rift System of the north-central United States. The fault, parallel to the south edge of the rift, has been interpreted as a rift-bounding normal fault that was inverted by subsequent compressional events, thrusting copper-bearing Portage Lake Volcanics (~ 1.1 Ga) over younger Jacobsville Sandstone. Geologic maps and cross sections published in the 1950s by the U. S. Geological Survey depict the fault with a well-defined, single, sinuous trace that is locally associated with smaller branch faults. Cross-sections from that time generally show a simple listric stratal geometry …

Genesis Of Trondhjemite By Low-Pressure Fraction Anatexis Of Hornblende-Gabbro At Alvand Plutonic Complex (Hamedan, Nw Iran): Insights From Geochemical Modelling., Federico Lucci, Adel Saki, Mirmohammad Miri, Ahmad Rabiee, John C. White

EKU Faculty and Staff Scholarship

Amphibole-dominated dehydration melting of gabbro is the primary process responsible for the genesis of adakites, low-K tonalites, modern trondhjemites, and plagiogranites aswell as Archean tonalite-trondhjemite-granodiorite suites that represent the earliest examples of continental crust. Previous literature has mostly focused on the role of Al-rich amphibole during anatexis of a mafic source and many of these studies have investigated this process through experimental melting runs. However, due to experimental boundary conditions, little is known about partial melting of amphibole-bearing mafic rock at temperatures < 800°C for upper crustal conditions (pressure < 500 MPa). Classic and forward thermobarometric modelling suggests that in situ trondhjemite leucosomes, hosted by Cheshmeh-Ghasaban mafic metatexites (Alvand Plutonic Complex, Hamedan, NW Iran), represent a rare natural case study of a low-temperature incipient amphibole-dominated anatectic event of a mafic source with a primary assemblage (Pl+Hbl+Cpx+Bt+Opx) typical of a hornblende-bearing gabbroic rock.

New Research On A Case Of Linear Discontinuous Ground Deformation (Ldgd), Andrzej Kowalski, Bartosz Apanowicz, Piotr Polanin

Journal of Sustainable Mining

LSDS is defined as surface fissures, steps as well as structures formed by them in the form of stairs (several steps), thresholds, ditches, and flexure. The paper presents a case study of formed LSDS – the origin, and possible methods to assess its occurrence on the basis of the research carried out in the Central Mining Institute. The authors showed that the presence of LSDS leads not only to the horizontal deformation but also contributes to the formation of vertical curvatures of terrain that cause fissures in the near-surface layer of the rock mass in the areas with a thick …

Delineating Of The Utica Shale/Point Pleasant Formation Play System To Determine Influence Of The Precambrian Basement In Northeastern Ohio, Jarrod R. Bridges

Electronic Theses and Dissertations

The Utica Shale/Point Pleasant Formation system has recently become a highly developed unconventional target for oil and natural gas production, leading to an increased desire for knowledge of the controls on deposition of this system. Precambrian basement features have long been known to affect deposition of older strata near these features across Ohio, but the effects of far field tectonics is not fully agreed upon. Precambrian faults and lineaments are known to exist and have been mapped, but are thought to have ceased their influence on deposition by the time of the Knox unconformity during the Cambrian. In the case …

Investigating The Timing Of Initial Louann Salt Flow And Its Relationship With The Gilbertown Fault Zone, Southwest Alabama, Avery Rosenbalm

Master's Theses

The Mesozoic Louann Salt extends through the northern GOM, extending onshore from eastern Texas to western Alabama and Florida. Along the landward terminus of the salt is a system of peripheral faults, including the Gilbertown Fault Zone bordering the Mississippi Interior Salt Basin to the north and east. This study sought to constrain the timing of fault movement and determine its relationship to the baswinward evacuation of Louann Salt through the use of a 3D seismic survey and well logs. By mapping Mesozoic formations and the peripheral fault system, lateral changes in formation thickness were used to generate fault expansion …

Sediment Provenance Of Tsunami Deposits: Implications For Assessing The Relative Intensity Of Paleotsunamis From The Sendai Coastline Of Japan, Tiffany Otai

Master's Theses

The 2011 Tohoku tsunami impacted the northeastern coast of Japan and caused unexpected damages due to the underestimation of this type of hazard. Of particular importance is the fact that geologic evidence for a predecessor event, the Jogan tsunami (CE 869), could have forecasted the severity of the 2011 Tohoku event. While the timing of tsunamis is important for effective hazard mitigation, outside of the 2011 Tohoku event, the intensity of past tsunamis remains unclear. To understand paleotsunami intensity, it is important to document characteristics of modern analogues like the 2011 event. This study utilizes surface distributions of foraminifera from …

Tectonic Evolution Of The Tucki Mountain Metamorphic Core Complex, Southeastern California: Evidence For Late Cretaceous Extension Within The Sevier-Laramide Orogen, William Killey Barba

UNLV Theses, Dissertations, Professional Papers, and Capstones

The exhumation of Cordilleran metamorphic core complexes from mid-crustal depths in the western U.S. Basin and Range Province has been classically associated with Cenozoic extension. However, recent studies reveal that extensional tectonic exhumation of numerous metamorphic core complexes initiated during the Late Cretaceous. New geologic mapping and structural analysis integrated with geochronology and thermochronology data provide evidence for a Late Cretaceous extensional shear zone, previously interpreted as Miocene in age, within the Tucki Mountain metamorphic core complex on the western flank of Death Valley, California. The shear zone occurs within the immediate footwall of the Miocene-Pliocene Tucki Mountain detachment fault …

The Fold Illusion: The Origins And Implications Of Ogives On Silicic Lavas, Graham Dm Andrews, Stuart Kenderes, Alan Whittington, Shelby L. Isom, Sarah Brown, Holly Danielle Pettus, Brenna Cole, Kailee Gokey

Faculty & Staff Scholarship

Folds on the surfaces of mafic lavas are among the most readily recognized geological structures and are used as first-order criteria for identifying ancient lavas on Earth and other planetary bodies. However, the presence of surface-folds on the surface of silicic lavas is contested in this study and we challenge the widely accepted interpretation that silicic lava surfaces contain folds using examples from the western United States and Sardinia, Italy. We interpret the ridges and troughs on their upper surfaces, typically referred to as ‘ogives’ or ‘pressure ridges’, as fracture-bound structures rather than folds. We report on the absence of …

Detrital Zircon (U-Th)/He Thermochronology In The Greater Caucasus: Implications For Thermal And Tectonic History Along-Strike, Kate Gutterman

LSU Master's Theses

Located along the northernmost boundary of the Arabia-Eurasia collision zone, the Greater Caucasus are a young, actively deforming mountain range striking WNW-ESE between the Black and Caspian Seas. Previous thermochronometric studies predominantly focused on the western portion of the range partially constrain the thermal and tectonic history of the Greater Caucasus. However, due to the complex nature of the tectonics in the region, multiple competing tectonic models have been suggested to explain the exact timing of collision and onset of rapid uplift. Furthermore, the Greater Caucasus exhibit competing along-strike gradients in modern shortening rates, mean annual precipitation, structural architecture and …

Volcanic Record Of The Arc-To-Rift Transition Onshore Of The Guaymas Basin In The Santa Rosalía Area, Gulf Of California, Baja California, Graham Dm Andrews

Faculty & Staff Scholarship

The Gulf of California is an archetype of continental rupture through transtensional rifting, and exploitation of a thermally weakened arc to produce a rift. Volcanic rocks of central Baja California record the transition from calcalkaline arc magmatism, due to subduction of the Farallon plate (ca. 24–12 Ma), to rift magmatism, related to the opening of the Gulf of California (<12 Ma). In addition, a suite of postsubduction rocks (<12 Ma), referred to as “bajaites,” are enriched in light rare-earth and other incompatible elements (e.g., Ba and Sr). These are further subdivided into high-magnesian andesite (with 50%–58% SiO2 and MgO >4%) and adakite (>56% SiO2 and MgO <3%). The bajaites correlate spatially with a fossil slab imaged under central Baja and are inferred to record postsubduction melting of the slab and subduction-modified mantle by asthenospheric upwelling associated with rifting or slab breakoff. We report on volcanic rocks of all three suites, which surround and underlie the Santa Rosalía sedimentary rift basin. This area represents the western margin of the Guaymas basin, the most magmatically robust segment of the Gulf of California rift, where seafloor spreading occurred in isolation for 3–4 m.y. (starting at 6 Ma) before transtensional pull-apart basins to the north and south ruptured the continental crust. Outcrops of the Santa Rosalía area thus offer the opportunity to understand the magmatic evolution of the Guaymas rift, which has been the focus of numerous oceanographic expeditions.

We describe 21 distinct volcanic and hypabyssal map units in the Santa Rosalía area, using field characteristics, petrographic data, and major- and trace-element geochemical data, as well as zircon isotopic data and …

Detrital Zircon Petrochronology For Sedimentary Provenance Analysis: Source To Sink Of The Mississippi/Missouri River Drainage Basin, Sage Denali Muttel

Graduate Theses/Dissertations

Detrital petrochronology can provide a detailed look into sedimentary provenance through integrated mineral radioisotopic ages with corresponding mineral chemistry. By combining U-Pb ages and Th/U values of detrital zircon from 13 samples collected from Quaternary sand deposits in the Upper Missouri, Yellowstone, Bighorn, Platte, Kansas, Arkansas, Mississippi, Red and Brazos Rivers, an interpretation of detailed signatures that record evidence of the evolution of the Mississippi/Missouri River drainage and the tectonic events that shaped it were observed. Low Th/U values in zircon correlate temporally to convergent magmatism, whereas, higher and more variable Th/U zircon are coeval with known extensional tectonism. Using …

The Rocky Ledge Fault, Shasta County, Ne California: Development And Morphology Of A Quaternary Oblique Normal Fault In Basalt, Gregory David Linscott Martin

Dissertations and Theses

Distinct morphology, variable vertical separation, and unique structural geometries are observed along the Rocky Ledge fault (RLF), an east-dipping, oblique normal fault in the tectonically complex Hat Creek Graben, Shasta County, NE California. Situated in the southern Cascade arc, the RLF is located at the boundary of the Klamath Mountains, Basin and Range, and Walker Lane Seismic Belt. The primary goal of this project is to better understand Quaternary deformation along the RLF. I developed detailed maps of geologic units and structures along the ~15 km length of the RLF. Map data informs assessment of fault geometry, scarp morphology, and …

Response Of Transient Base Level Signals To Erodibility Contrasts In Bedrock Streams, Joshua A. Wolpert

LSU Master's Theses

It has long been recognized that bedrock streams gradually adjust their slopes towards topographic steady state, an equilibrium state between rock uplift rate and erosion rate. Tectonic geomorphology studies often analyze stream profiles for clues of this adjustment, which can initiate from changes in tectonic and climatic forcings. The stream power incision model, the most widely utilized framework with which to interpret bedrock stream profiles, predicts that streams perturbed from topographic steady state by changes in bedrock erodibility or uplift rate adjust their slopes to return to topographic steady state through upstream propagating waves of incision, or knickpoints. Under the …

Integrated Studies Of Intracontinental Deformation In The Interior Western Usa, Cretaceous To Recent, Jacob Oliver Thacker

Earth and Planetary Sciences ETDs

The advent of plate tectonic theory satisfactorily explained a number of deformation belts around the world. However intracontinental deformation (deformation inboard of a plate margin) remains poorly understood in plate tectonic models. In order to further our understanding of intracontinental tectonics and its effects, this dissertation examines paleotectonic and neotectonic settings within the interior western USA.

Chapter 1 focuses on late Miocene–Recent deformation inboard of the San Andreas plate margin fault and its role on the integration history of the lower Colorado River. The neotectonic analysis included geometric and kinematic fault data collected in key geologic units to characterize the …

Testing A Drone-Based Magnetic Field Surveying System, Erik Jacobson, Irina Filina

UCARE: Research Products

Aeromagnetic surveys are conducted by geoscientists to study subsurface geologic structures, such as faults. This type of survey uses a magnetometer mounted upon an airborne vehicle to collect magnetic field data. Magnetic anomalies are caused by variations in subsurface geology, namely in magnetic properties of subsurface rocks. Jacobson and Filina (2019) reported on the development of a new low cost drone, based magnetic field surveying system by the UNL Geophysics Team. This drone-based magnetic system is capable of collecting high resolution data at low speeds and low altitudes. The current study focuses on testing this system by conducting two flights …

Quantifying Tekeze River Canyon Incision On The Ethiopian Plateau From Low-Temperature Apatite Thermochronology, Jacob Thomas Grigsby

Masters Theses & Specialist Projects

The Ethiopian Plateau in East Africa features dynamic topography, deep river incision (~1.5 km), active tectonics, continental rifting, volcanic terrain and ~2 km of plateau uplift. Situated on the northwestern part of the Ethiopian Plateau, the Tekeze River is one of the two major rivers associated with incising and documenting the recent geologic history of the uplifted plateau landscape. The consequential Tekeze River incision into the uplifted Ethiopian Plateau is associated with the arrival and impingement of the Afar mantle plume as evidenced by the presence of thick sheets of Cenozoic flood basalts (~30 Ma). However, the Cenozoic to present-day …

Characterization Of Magma Storage And Dynamics At Akutan, Semisopochnoi, And Okmok Volcanoes From Analytical And Numerical Models Of Geodetic, Seismic, And Petrologic Data, Kimberly Degrandpre

Earth Sciences Theses and Dissertations

Volcanic eruptions can cause significant socioeconomic loss, but a better understanding of the processes and dynamics influencing the evolution of volcanic plumbing systems will advance the development of eruption forecasting models that will ultimately mitigate hazards and risks associated with eruptive events. Geologic and geophysical data must be integrated in 3D, finite- element, multiphysical, numerical models to define the coupled evolution of magmatic and crustal stress regimes in volcanic environments, but in data limited regions this is not always an option. The remote nature of the Aleutian Island Arc restricts ground-based monitoring and sampling efforts, and due to sparse temporal …

Testing Interpretations Of The Displacement Magnitude Of The Teton Fault And Uplift Of The Teton Range, Wyoming With Integrated Flexural-Kinematic And Thermal Modeling, Autumn Helfrich

Theses and Dissertations--Earth and Environmental Sciences

The Teton fault is a range-front normal fault in northwestern Wyoming. Previous estimates of the maximum displacement (D_max) on the Teton fault cover a wide range (2 - 11 km). Discrepancies also exist regarding the slip onset timing, which spans 2 - 13 Ma. To address these discrepancies, the exhumation history of the Teton Range is here investigated using forward flexural-kinematic (Move) and thermal-kinematic (Pecube) models that can be compared with previously reported apatite fission track (AFT) and apatite (U-Th)/He (AHe) ages from Mount Moran, which has been previously hypothesized to represent the …

Reconstruction Of The 2018 Anak Krakatau Collapse Using Planetscope Imaging And Numerical Modeling, Davide Saviano

Dissertations, Master's Theses and Master's Reports

The study was focused on the Anak Krakatau sector collapse that occurred on 22 December 2018 in the Sunda Strait (Indonesia). The goal of the study was to monitor and analyze changes of the volcanic edifice and to try to understand causes that may have predisposed and triggered the sector collapse.

The use of different remote sensing techniques allowed the acquisition of thermal data, SO₂ emission data, structural data and the identification and analysis of the eruptive events that occurred on Anak Krakatau in the period from 1° January 2016 to 28 February 2019. The acquisition of 1221 thermal …

Documenting The Earthquake History Of The Thousand Springs Fault In Summer Lake Basin, Oregon, Usa, Elizabeth Curtiss

All Master's Theses

Defining seismic hazards in low-strain-rate regions such as the northwestern Basin and Range can be difficult due to the infrequency of earthquakes. Revealing the earthquake records of low-strain-rate regions can refine our understanding of the variability of earthquake sizes and recurrence intervals, however, which can ultimately improve hazard analysis. Four active normal faults form the Summer Lake basin, in the northwestern Basin and Range: The Thousand Springs (TSF), Ana River (ARF), Slide Mountain, and Winter Ridge faults. Other than the TSF, the faults in the Summer Lake basin have documented histories that include surface-rupturing (>M6) earthquakes. Scarps along the …

Mapping And Modeling The Seattle Fault Tsunami Inundation In Puget Sound, David Bruce

All Master's Theses

Coastal communities of Puget Sound are susceptible to tsunami inundation from multiple sources. Two sources of potential tsunami hazard that threaten the region are earthquakes on crustal faults in the Puget Lowlands, or earthquakes originating on the Cascadia subduction zone. This study investigated two coastal marshes in Puget Sound, Deer Lagoon and Doe-Kag-Wats, for evidence of a paleotsunami record to combine with tsunami modeling, in order to predict how future events could inundate Puget Sound. A deposit, interpreted as a paleotsunami, is traceable thought the marsh stratigraphy near the modern day tidal inlet of Deer Lagoon, a site that has …