Earth Sciences Commons^™

Structural Analysis And Interpretation Of Deformation Along The Keweenaw Fault System From Lake Linden To Mohawk, Michigan, Nolan G. Gamet

Dissertations, Master's Theses and Master's Reports

The Keweenaw fault is likely the most significant and most studied fault associated with the Midcontinent Rift System. The fault roughly bisects the Keweenaw Peninsula and places Portage Lake Volcanics (~1.1 Ga) over much younger Jacobsville Sandstone (~1.0 Ga). Published bedrock geology maps with cross sections from the 1950s show the fault as a single continuous trace that is locally associated with smaller cross faults and splays. The accompanying cross-sections show hanging-wall volcanic strata having a well-defined, listric geometry with dip decreasing away from the fault to the northwest.

This M.S. thesis presents a structural analysis and interpretation of the …

Digital Appendix Of Masters Thesis "Constraining Deformation Mechanisms Of Damage Zones: A Case Study Of The Shallow San Andreas Fault At Elizabeth Lake, Southern California, James P. Evans, Caroline Studnicky

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We performed macroscopic, optical petrographic, scanning electron microscopy, and geochemical analyses on rock core acquired across the San Andreas Fault at Elizabeth Lake, California, in order to understand the distribution and accommodation of fault-related slip and energy within the shallow damage zone of this continental scale strike-slip fault. We characterized the deformation structures, alteration textures, and elemental variabilities to constrain the properties of the uppermost ~2 km fault-related damage zone at this site. We identified evidence for coseismic slip in the form of pulverized rocks, injection veins, clay-clast aggregates, and pseudotachylyte, and aseismic slip through calcite twins, dilatant vein fills, …

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 …

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 …

Experimental Polycrystal Stress Mapping Using Raman Spectroscopy, Genevieve C. Kidman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Stress conditions leading to rock deformation influence how a rock will ultimately deform. However, the internal distribution of stress in an elastically anisotropic rock under load, a precursor to rock deformation, is not well understood. Two models that may describe the distribution of stress in polycrystals include the Reuss bound and stress percolation. The Reuss bound, when applied to a polycrystal, describes isostress on each grain resulting in homogeneous intragranular strain and heterogeneous intergranular strain. The stress percolation model involves a network of strong contacts or force chains containing domains of high stress interwoven through areas of lower stress that …

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 …

Nanotextural And Nanochemical Constraints On The Role Of Heat In The Development Of Crystalline-Hosted, Silica-Rich Fault Mirrors In The Wasatch Fault Damage Zone, Utah, Usa, Leah M. Houser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes occur on faults, or rock that has experienced displacement at depth. Experimental work on a range of rock types reveals that >90% of earthquake energy on fault surfaces is given off as heat. Heat weakens rock and promotes earthquake rupture propagation. Thin (<0.5mm), high-gloss, "polished", light-reflective exposed fault surfaces are called fault mirrors (FMs). Fault mirrors may record rapid thermal, textural, and chemical changes that occur during an earthquake event.

The Wasatch Mountains are a N-S trending mountain range in Northern Utah that are the backdrop for Salt Lake City, Provo, Ogden, and Brigham City. This mountain range is currently built by the active Wasatch fault, and includes the exposed Wasatch fault damage zone. Many segments of the Wasatch fault are overdue for a potentially catastrophic …

Evidence For Polyphase Deformation In The Shear Zones Bounding The Chester And Athens Domes, Southeastern Vermont, From 40ar/39ar Geochronology, Kristin Schnalzer

Graduate College Dissertations and Theses

The Chester and Athens Domes are a composite mantled gneiss dome in southeast Vermont. While debate persists regarding the mechanisms of dome formation, most workers consider the domes to have formed during the Acadian Orogeny. This study integrates the results of 40Ar/39Ar step-heating of single mineral grains, or small multigrain aliquots, with data from microstructural analyses from samples collected in multiple transects across the dome-bounding shear zone(s) in order to understand the relationship between metamorphism and deformation. Results from the sheared units along the north and south transects are presented from west to east. In the north, hornblende from the …

Analysis Of Small Faults In A Sandstone Reservoir Analog, San Rafael Desert: Implications For Fluid Flow At The Reservoir-Scale, Leslie Noël Clayton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We examined small-displacement faults in the Jurassic Entrada Sandstone adjacent to the Iron Wash Fault, central Utah east of the San Rafael Swell, in order to describe the nature and timing of past fluid movement and deformation in the Entrada Sandstone. Using field studies, microscopy, and X-ray diffraction analysis, we identified mineralized fractures and cementation features in association with deformation bands and fractures at the interface of the Earthy and Slick Rock Members of the Entrada Sandstone.

Where the faults cross the Earthy-Slick Rock Member interface, deformation band faults in the Slick Rock Member become opening-mode fractures in the Earthy …

Paleomagnetic Investigation Of Igneous Rocks Deformed By The Keweenaw Fault In The Northwestern Keweenaw Peninsula., Daniel Trekas

Dissertations, Master's Theses and Master's Reports

One of the most prominent structural features associated with the ~1.1 Ga Midcontinent Rift (MCR) system is the >350 km long Keweenaw Fault that bisects the Keweenaw Peninsula, separating the MCR-related Portage Lake Volcanics (PLV) and the younger Jacobsville Sandstone (JS). The fault trend is NE-NNE over most of its length, but changes to an easterly direction along the shore of Bête Grise Bay near the end of the peninsula. Conventionally, the Keweenaw Fault has been considered to be a continuous reverse (dip-slip) fault formed by inversion of an original rift-bounding normal fault during the Grenville Orogeny. However, recent mapping …

The Sedimentary Record Of Eocene Deformation In The Interior Of The Southern Canadian Cordillera, Erica May Rubino

Theses and Dissertations

Eocene sedimentary strata exposed in the interior of the southern Canadian Cordillera (SCC) in British Columbia (BC) and northernmost Washington (WA) record a poorly understood history of extension-related deformation in the hinterland of the orogen. Today these strata are exposed in isolated, distinct outcrop belts, although the nature of the original basin(s) is unknown. We examined 650 m of Eocene strata, analyzed 2,995 detrital zircons for uranium-lead (U-Pb) ages, and measured 67 detrital zircons for Hf isotope systematics in an effort to better understand the physiography of the SCC during this time period. Eocene strata consist of clast- and matrix-supported …

Effect Of A Pre-Existing Lattice Preferred Orientation On The Strength Of Quartzite, Casey Braccia

Williams Honors College, Honors Research Projects

Ductile deformation of the middle to lower crust during interseismic periods influences loading of brittle faults in the upper crust. Quartz is a common mineral in the middle to lower continental crust and is thought to significantly affect the strength of this zone. Quartz deformed by dislocation creep produces a crystallographic alignment of quartz grains, or lattice preferred orientation (LPO), because deformation is easier along specific crystallographic planes and directions. However, formation of a LPO may cause the strength of the quartz aggregates to be anisotropic, approaching the properties of a single crystal.

In order to determine the viscous anisotropy …

The Impact Of Fe-Ti Oxide Concentration On The Structural Ridgity Of The Lower Oceanic Crust, Atlantis Bank, Southwest Indian Ridge, Daniel Winkler

Master's Theses

Fe-Ti oxides are important components of oceanic core complexes (OCC) formed at slow-spreading mid-ocean ridges since Fe-Ti oxides are more susceptible to crystal-plastic deformation than silicate minerals. This study investigated the predicted relationship between the presence and concentration of Fe-Ti oxides and the presence and intensity of crystal-plastic deformation in gabbroic samples from Atlantis Bank, Southwest Indian Ridge (SWIR). Atlantis Bank is an oceanic core complex that formed through the exhumation of lower oceanic crust along a detachment fault. OCCs form along slow-spreading ridges and are characterized by the complex interactions between magmatism and lithospheric extension, thus making these complexes …

Mechanisms Of Shear Zone Localization And Raman Thermobarometry In Spinel Peridotites From The Alpine Fault, New Zealand, Emily J. Lubicich

Dissertations and Theses

A suite of xenoliths from two localities on South Island, New Zealand, exhibit rare microstructures and provide information on deformation during the early stages of development of the Alpine Fault. The first set of samples has evidence of dislocation creep with subgrains, recrystallized grains, undulose extinction and a lattice preferred orientation. These samples also show evidence of post deformation static grain growth with polygonal grains, 120° triple junctions, and euhedral grains within larger grains of the same phase. Samples from the second locality also show evidence of dislocation creep but with minimal static grain growth. This set also has a …

Dating Deformation In The Palmer Zone Of Transpression, Central Massachusetts: Temporal Constraints On Models For Progressive Deformation In The Middle Crust, James K. Mcculla

Theses and Dissertations--Earth and Environmental Sciences

The Palmer Zone of Transpression (PZoT) in the Bronson Hill zone of central Massachusetts is an expression of late Paleozoic oblique convergence between Avalonia and Laurentia. The steeply W-dipping, N-S trending PZoT is defined by bounding high strain zones (Mt. Dumplin on west, Central Maine and Conant Brook on east) of opposing shear sense enclosing the Monson orthogneiss. Research was designed to establish the timing of deformation to test the hypothesis that strain in transpressional systems occurs contemporaneously. An understanding of the timing of deformation in this zone could elucidate the mechanisms that formed the zone and contribute to a …

Microstructure And Deformation Mechanism Analysis Of Carbonate Rock Located In An Anticline, Natalie R. Zidd

Williams Honors College, Honors Research Projects

Rock samples were collected from the Tensleep formation in the Seminoe Mountains located in Carbon County, Wyoming. These samples were analyzed to determine the deformation mechanisms operating during small scale displacement faulting. There are three distinct zones included in the sample which includes the undeformed Tensleep, fine grained layers with grain size variation, and porous layers with grain size variation. The microstructures in the fine grained layer were consistent with deformation by crystal plastic deformation mechanisms; whereas, the microstructures in the porous layer were consistent with brittle deformation mechanisms. The microstructures in these rocks are nearly identical to those observed …

Mesoscale Deformational Features Near Outcrop Analogs Of A Reservoir-Seal Interface: Implications For Seal Failure, Santiago L. Flores

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The boundary that separates reservoir rocks from caprock seals is generally considered a flow barrier for reservoir fluids. Buoyant fluids do no flow through the caprocks because they have low permeability and molecular forces at the base of the caprock resist upward flow. Deformation at the reservoir/caprock boundary may include fractures that increase permeability and lessen the effect of the molecular forces.

The injection and storage of carbon dioxide (CO₂) in porous sandstone with effective top seals below earth’s surface is a possible solution for reducing the amount of human-created CO₂ in the atmosphere. Uplift and erosion …

A Surface Displacement Analysis For Volcan Pacaya From October 2001 Through March 2013 By Means Of 3-D Modeling Of Precise Position Gps Data, Brianna R. Hetland

Dissertations, Master's Theses and Master's Reports - Open

Volcán Pacaya is one of three currently active volcanoes in Guatemala. Volcanic activity originates from the local tectonic subduction of the Cocos plate beneath the Caribbean plate along the Pacific Guatemalan coast. Pacaya is characterized by generally strombolian type activity with occasional larger vulcanian type eruptions approximately every ten years. One particularly large eruption occurred on May 27, 2010. Using GPS data collected for approximately 8 years before this eruption and data from an additional three years of collection afterwards, surface movement covering the period of the eruption can be measured and used as a tool to help understand activity …

Glacier Slip And Seismicity Induced By Surface Melt, Peter L. Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Miriam Jackson, Mark E. Mathison, Denis Cohen

All Faculty Scholarship for the College of the Sciences

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed …

Rapid River Incision Across An Inactive Fault - Implications For Patterns Of Erosion And Deformation In The Central Colorado Plateau, Joel L. Pederson, Neil Burnside, Zoe Shipton, Tammy M. Rittenour

Geosciences Faculty Publications

The Colorado Plateau presents a contrast between deep and seemingly recent erosion and apparently only mild late Cenozoic tectonic activity. Researchers have recently proposed multiple sources of epeirogenic uplift and intriguing patterns of differential incision, yet little or no quantitative constraints exist in the heart of the plateau to test these ideas. Here, we use both optically stimulated luminescence (OSL) and uranium-series dating to delimit the record of fluvial strath terraces at Crystal Geyser in southeastern Utah, where the Little Grand Wash fault crosses the Green River in the broad Mancos Shale badlands of the central plateau. Results indicate there …

Earthquake Petrology: Linking Fault-Related Deformation To The Earthquake Cycle, Mitchell R. Prante

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Faults have a controlling influence on a variety of geologic processes including fluid flow, the mechanical behavior of the crust, and seismicity. The geologic sciences have long recognized that faults generate earthquakes; however, few indicators of ancient earthquakes exist in fault-zones. This dissertation documents several indicators for the preservation of ancient earthquakes in fault-zones including frictional melt (pseudotachylyte), highly-polished fault slip surfaces, and hydrothermal alteration.

These deformation products result from rapid generation of frictional heat during earthquakes. This dissertation also focuses on the seismic potential of continental low-angle normal faults (LANF). We document the preservation of voluminous pseudotachylyte along a …

Map Of The Late Quaternary Active Kern Canyon And Breckenridge Faults, Southern Sierra Nevada, California, C. C. Brossy, K. I. Kelson, Colin B. Amos, J. N. Baldwin, B. Kozlowicz, D. Simpson, M. G. Ticci, A. T. Lutz, O. Kozaci, A. Streig, R. Turner, R. Rose

Geology Faculty Publications

Surface traces of the Quaternary active Kern Canyon and Breckenridge faults were mapped via aerial reconnaissance, analysis of light detection and ranging (LiDAR) elevation data, review and interpretation of aerial photography, field reconnaissance, and detailed field mapping. This effort specifically targeted evidence of late Quaternary surface deformation and, combined with separate paleoseismic investigations, identified and characterized the North Kern Canyon, South Kern Canyon, and Lake Isabella sections of the Kern Canyon fault and the Breckenridge fault. The mapping presented here provides definitive evidence for previously unrecognized Holocene and late Pleistocene east-down displacement along the Kern Canyon and Breckenridge faults. Our …

Rock Properties And Structure Within The San Andreas Fault Observatory At Depth (Safod) Borehold, Northwest Of Parkfield, California: In Situ Observations Of Rock Deformation Processes And Fluid-Rock Interactions Of The San Andreas Fault Zone At ~ 3 Km Depth, Kelly Keighley Bradbury

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The San Andreas Fault Observatory at Depth (SAFOD) is a scientific drilling experiment situated along the central creeping segment of the San Andreas Fault, near Parkfield, California, and north of a segment of the fault that has experienced large historical earthquakes. Drilling into active fault zones allows scientist’s to examine in situ rock samples and to record real-time data.

The main goal of this study is to characterize the geologic setting and rock properties of the San Andreas fault at ~ 3 km depth in the SAFOD borehole. In this region, the fault deforms nearly continuously through aseismic creep and …

Heterogeneous Deformation Of Gabbroic Rocks, Calvin Mako

Honors College

The Grenville province is the exhumed remains of a more than 1 billion year old orogen. Mid to lower crustal rocks of this orogen are now exposed at the surface, affording the opportunity to examine deeper crustal processes during orogeny. I have studied an outcrop of anorthositic gabbro from the Central Metasedimentary Belt boundary thrust zone (CMBbtz) in the Grenville province of southern Ontario. The CMBbtz is a region that separates two major lithotectonic domains of this part of the Grenville province and is thought to have accommodated large scale thrusting in the mesoproterozoic era. The CMBbtz comprises large crystalline …

Multiple Deformation Mechanisms Operating At Seismogenic Depths: Tectonic Pseudotachylyte And Associated Deformation From The Central Sierra Nevada, California, Mitchell R. Prante, James P. Evans

Geosciences Presentations

No abstract provided.

The Marriage Of Eolian Rock Properties And Deformation Of The Nugget Formation; Anschutz Ranch East Field: Northeast Utah And Southwest Wyoming, Dustin J. Keele

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Nugget Formation in the Anschutz Ranch East field, northeast Utah and southwest Wyoming, provides an exceptional example of how primary eolian rock properties have a considerable influence on the style of structural deformation. Both new and existing subsurface data were integrated for an overall characterization of sedimentologic and diagenetic heterogeneities, which demonstrate relationships with different styles of structural compartmentalization in reservoirs. The Anschutz Ranch East field is a large asymmetric anticlinal trap in the Utah-Wyoming thrust belt. Three cores were analyzed in order to investigate brittle deformation in eolian facies: dune, apron, and interdune. Selected cores are located along …

Source Of Meta-Igneous Blocks And Structure Of The Colebrooke Schist In The Snowcamp Peak Area, Pickett Peak Terrane, Southwestern Oregon, Jennifer Katrib

Geology Theses and Dissertations

The Colebrooke Schist of the Pickett Peak terrane, southwestern Oregon, is the easternmost, structurally highest unit of the Late Mesozoic-Cenozoic Franciscan Accretionary Complex. The Colebrooke Schist consists of mostly transitional greenschist-blueschist-facies meta-sedimentary rocks with common blocks of meta-volcanics and serpentinites, rare talc-schists and meta-plutonic rocks. The Colebrooke Schist meta-volcanic blocks are greenstones, in many cases with visible relict pillow structures and relict igneous textures.
Fifteen meta-volcanic samples and one meta-plutonic sample were analyzed by XRF and ICP-MS and were plotted with analyses from Plake (1989) and Coleman (1972). The Colebrooke Schist meta-volcanic rocks plot in mid-ocean ridge basalt (MORB), island …

Aragonite Pseudomorphs In High Pressure Marbles Of Syros, Greece, John B. Brady, Michelle J. Markley, John C. Schumacher, John T. Cheney, Grace A. Bianciardi

Geosciences: Faculty Publications

Numerous rod-shaped calcite crystals occur in the blueschist to eclogite facies marbles of Syros, Greece. The rods show a shape-preferred orientation, and the long axes of the rods are oriented at a large angle to foliation. The crystals also have a crystallographic-preferred orientation: calcite c-axes are oriented parallel to the long axes of the rods. Based on their chemical composition, shape, and occurrence in high-pressure marbles, these calcite crystals are interpreted as topotactic pseudomorphs after aragonite that developed a crystallographic-preferred orientation during peak metamorphism. This interpretation is consistent with deformation of aragonite by dislocation creep, which has been observed …

Mantle Deformation Beneath Southern Africa, Paul G. Silver, Stephen S. Gao, Kelly H. Liu, Kaapvaal Seismic Group

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Seismic anisotropy from the southern African mantle has been inferred from shear-wave splitting measured at 79 sites of the Southern African Seismic Experiment. These data provide the most dramatic support to date that Archean mantle deformation is preserved as fossil mantle anisotropy. Fast polarization directions systematically follow the trend of Archean structures and splitting delay times exhibit geologic control. The most anisotropic regions are Late-Archean in age (Zimbabwe craton, Limpopo belt, western Kaapvaal craton), with delay times reduced dramatically in off-craton regions to the southwest and Early-Archean regions to the southeast. While thin lithosphere can account for weak off-craton splitting, …

Analysis Of Deformation Data At Parkfield, California: Detection Of A Long-Term Strain Transient, Stephen S. Gao, Paul G. Silver, Alan T. Linde

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Analysis of more than a decade of high-quality data, particularly those from the two-color electronic distance meter (EDM), in the Parkfield, California, area reveals a significant transient in slip rate along the San Andreas Fault. This transient consists of an increase in fault slip rate of 3.3 ± 0.9 mm/yr during 1993.0 to 1998.0. The most reliable fault creep instruments show a comparable increase in slip rate, suggesting that the deformation is localized to the fault which breaks the surface. There was also an increase in precipitation around 1993. It is unlikely, however, that this anomaly is due directly to …