Physical Sciences and Mathematics Commons^™

U-Pb Zircon Geochronology And Structure Of Regional Blueschist Units In The Easton Metamorphic Suite, Northwest Cascades, Wa, Katherine Lang

WWU Graduate School Collection

The Easton metamorphic suite of the Northwest Cascades Thrust System (NWCS) is a well-preserved subduction accretion complex in Washington State. The regional blueschist units of the Easton metamorphic suite include the Mt. Josephine semi-schist, Darrington Phyllite, and Shuksan greenschist/blueschist and all are interpreted to have accreted after the onset of Jurassic subduction beneath North America. This study uses zircon U-Pb geochronology, structure, and field observations to test the regional correlations between units in the Easton metamorphic suite and address models for the timing of subduction accretion along the North American margin in the Late Jurassic – Early Cretaceous. The results …

Joint Spacing In The Caples Lake Granodiorite Of The Sierra Nevada Batholith In Eldorado National Forest, California: A Comparative Analysis Of Joint Sets And Data Resolution, Jimmy Wood

Theses/Capstones/Creative Projects

Joints are the most common deformation structure in the Earth’s upper crust and exert a significant influence on structural stability, landscape morphology, and fluid flow . Therefore, a greater understanding of fracture parameters (e.g., length, aperture, etc.) allows us to more accurately predict their presence, persistence, and prevalence, in the subsurface . We study the fracture spacing of two sub-orthogonal joint sets—66 NE-246 SW and 330 NW-150 SE—in the Caples Lake granodiorite of the Sierra Nevada Batholith, California. Specifically, we investigate 1) their spacing distributions with a keen interest in power-law (fractal) spacing, 2) distribution comparisons between master and cross …

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 …

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 …

A Gis-Based Method For Archival And Visualization Of Microstructural Data From Drill Core Samples., Elliott Holmes

Electronic Theses and Dissertations

Core samples obtained from scientific drilling could provide large volumes of direct microstructural and compositional data, but generating results via the traditional treatment of such data is often time-consuming and inefficient. Unifying microstructural data within a spatially referenced Geographic Information System (GIS) environment provides an opportunity to readily locate, visualize, correlate, and explore the available microstructural data. Using 26 core billet samples from the San Andreas Fault Observatory at Depth (SAFOD), this study developed procedures for: 1. A GIS-based approach for spatially referenced visualization and storage of microstructural data from drill core billet samples; and 2. Producing 3D models of …

Fault Deformation At The Base Of And Within The Crescent Formation Along The Dosewallips River, Olympic Mountains Peninsula, Washington, Usa, Christine Meryl Maher

Dissertations and Theses

The Olympic Mountains, in the cost ranges of northwest Washington, expose a Cenozoic accretionary complex east of the Cascadia Subduction Zone. Accreted material consists of metasedimentary deposits thrust eastward beneath a basaltic terrane (i.e., the basaltic Crescent Formation and the basal Blue Mountain Unit [BMU] turbidite) along a major fault, the Hurricane Ridge Fault (HRF). Recent isotopic dating of zircons from the BMU indicate that it is about 8 my younger than the basalt, implying another major fault may exist east of the HRF, between the BMU and the Crescent Fm. Field observations, data, and samples for microstructural analysis were …

A Characterization Of Structures Across The Hurricane Ridge Fault In The Southeastern Olympic Peninsula, Wa, Hamma Hamma River Transect, Veronica Catherine Biesiada

Dissertations and Theses

The Olympic Mountains in northwestern Washington, USA are defined by the arcuate shape of the basaltic Crescent Formation (Fm.) that wraps a faulted and folded meta-sedimentary core. This area was developed through accretion and exhumation by subduction-related processes, but how this relates to the deformational history of the area is not fully understood. The region has been mapped geologically, however little focus has been placed on interpreting meso-scale structures. This study investigates structures along a transect where the Hamma Hamma River crosses the Hurricane Ridge Fault, which juxtaposes the meta-sedimentary core (west) and the basaltic Crescent Fm. (east). In the …

Fault Kinematics Of The Southern Rio Grande Rift: Exploring The Possibility Of Fault Reactivation, Georgina Rodriguez Gonzalez

Open Access Theses & Dissertations

The region in and around the southern Rio Grande rift has experienced a long and complex tectonic history since the Precambrian era. In addition to recording extension directions due to the opening of the Rio Grande rift, faults can also possibly record contractional deformation related to the Laramide orogeny, extension along the boundary of the Mesozoic Chihuahua Trough, and possibly strike - slip movement since the Precambrian related to the Texas Lineament. The northern and central segments of the Rio Grande rift preserve mostly N - S-trending faults, whereas the southern segment preserves NW - SE-trending faults. The main hypoThesis …

Ductile Deformation In The Central Panamint Mountains - A Multi-Disciplinary Approach To A Multi-Dimensional Problem., Tai Antonia Subia

Open Access Theses & Dissertations

This study provides new insights into the geometry and timing of ductile, syn-metamorphic structures in the central Panamint Mountains of eastern California. The study focused on Surprise Canyon, where exposures of Meso- to Neoproterozoic miogeocline rocks, reworked crystalline basement, and syn-metamorphic granitoids record fabric overprints indicative of at least two distinct dynamo-thermal metamorphic events. Prograde metamorphism at greenschist and amphibolite metamorphic facies conditions occurred during Early Jurassic plutonism based on deformation of a dioritic pluton with a U-Pb date reported here of 175.6 ± 3.2 Ma. Mid Jurassic deformation (D1) generated the main continuous cleavage in the rocks (S1) as …

Structural Style And Stratigraphic Architecture Of The Northeastern Brooks Range, Alaska, Benjamin G. Johnson

Graduate Theses, Dissertations, and Problem Reports

The Arctic Alaska–Chukotka microplate is a large Mesozoic–Cenozoic composite terrane that resides at the northern limit of the North American Cordillera. Although its Mesozoic origins are assuredly linked to the opening of the Amerasian Basin of the Arctic Ocean, its Paleozoic origins can be linked to at least three separate paleocontinents, including northern Laurentia, Baltica, and Siberia. Across the Arctic Alaska portion of the microplate, an internal, mid-Paleozoic suture zone presumably separates rocks of the North Slope subterrane (Laurentian affinity) from a collection of smaller subterranes in the southern Brooks Range and Seward Peninsula (Baltic affinity).

The mountains of the …

An Outcrop Based Study Of The Weches Formation In Sabine County, Texas: Investigating Its Unconventional Resource Potential Through The Study Of Stratigraphy, Sedimentology, Petrology, And Geochemistry, Talban Kantala

Electronic Theses and Dissertations

Fresh Weches Formation (Middle Eocene) exposures found in aggregate quarries in Sabine County, Texas, were sampled, measured, and logged with gamma-ray spectrometry (GRS). Sedimentology and petrology characteristics of Weches samples were analyzed through thin section, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and GRS Th/K ratios analyses. The source rock quality of the Weches was evaluated with geochemical techniques involving total organic carbon (TOC), Rock-Eval pyrolysis, and GRS Th/U ratios.

The Weches, in the study area, is 27.4 meters thick, and delineated into three major stratigraphic facies: an upper marginal marine prodeltaic facies (Therrill Member) comprised of silty claystones and …

Structural Synthesis And Spatial Distribution Of A 335 Ma Igneous Suite From The Eastern Blue Ridge, Alabama Appalachians, Avery Rosenbalm

Honors Theses

The Appalachian range was formed by three orogenies, the most recent being the Alleghanian beginning at ~330 Ma. A small pluton outcropping along Highway 280 near Alexander City, AL, called the 280 granodiorite, has been dated at ~335 Ma and intrudes the Devonian Elkahatchee Quartz Diorite (EQD). While little work has been done on the intrusion, it is significant because of its age: all deformation of the intrusion should be related to the Alleghanian orogeny, while most other bodies in the region exhibit significant overprinting due to previous successive orogenies. The pluton was mapped constraining the geographic extent, which is …

An Investigation Of Hydrothermal Veins Along The Foy Offset Dyke, Sudbury Impact Structure, Ontario, Sarah Ann Codyre

Electronic Thesis and Dissertation Repository

A multi-stage hydrothermal system is related to the 1.85 Ga Sudbury impact structure. This system began in the Sudbury Igneous Complex (SIC) and radiated outward along the offset dykes. Through the combination of orientation measurements of veins in the field, petrography and geochemistry of these veins, this study has determined that there are four types of hydrothermal epidote-quartz veins categorized by their orientation, petrography and geochemistry. This study discovered that there are general trends with increasing distance from the SIC along the Foy Offset Dyke. From this it can be concluded that this is in fact SIC-driven hydrothermal event not …

Conical Folds -- An Artifact Of Using Simple Geometric Shapes To Describe A Complex Geologic Structure, Avery Joseph Welker

Masters Theses

"Accurate representation of the 3D shapes of natural folds is essential to characterization of the dynamic models for fold formation. Geometrical analysis of folds commonly relies upon analyzing patterns defined by the variation in the orientation of poles to planar surfaces deformed by a shortening event when plotted using graphical calculators (e.g., stereogram, polar tangent diagrams) to interpret the shape of folds. Stereograms for which orientation data define small circles are classified as non-cylindrical regular folds and are interpreted as "conical folds," where the shape of the fold is represented by a cone that terminates at a point. Utilizing similar …

Kinematic, Metamorphic, And Geochronologic Constraints On The Evolution Of The Lhagoi Kangri Gneiss Dome, Southern Tibet: Insight Into Mid-Crustal Processes During Himalayan Orogenesis, Timothy Francis Diedesch

Doctoral Dissertations

The north Himalayan gneiss domes are a series of isolated structures in southern-central Tibet that expose middle crust and record an early history of deformation, metamorphism, and partial melting. The domes are windows into the processes and physical conditions that promoted growth and uplift of the Himalaya during the early stage of collision (Eocene to Miocene) between India and Asia. Mechanisms responsible for creating the north Himalayan gneiss domes are crucial to understanding the early tectonic evolution of large orogens, such as the Himalaya, particularly with respect to crustal rheology and how middle crust is exhumed in collisional settings. Models …

Stratigraphy And Structure Of A South-Trending Structural High, Northern Arkoma Basin, Arkansas, Yirong Chen

Graduate Theses and Dissertations

The Arkoma Basin is a Carboniferous peripheral foreland basin in southeastern Oklahoma and west-central Arkansas. The formation of the Arkoma Basin is a result of a collision between the North American Plate and the Sabine Terrane. To the north of the basin, there is a structural high that extends southward from the Arkoma Shelf into the basin. This structure is in contrast with the prevailing east-trending strike of structures in the northern margin of the basin and is poorly defined. This paper examined the structure of the salient with stratigraphic and structural cross sections. Across the study area, two NS …

The Structural Evolution Of A Portion Of The Median Batholith And Its Host Rock In Central Fiordland, New Zealand: Examples Of Partitioned Transpression And Structural Reactivation, Hannah Jane Blatchford

Graduate College Dissertations and Theses

This thesis presents the results of structural analyses and detailed field mapping from a region near Adams Burn in central Fiordland, New Zealand. The region preserves assemblages of metasedimentary and metaigneous rocks deposited, intruded, and ultimately metamorphosed and deformed during the growth of a Gondwana-margin continental arc from Cambrian-Early Cretaceous. Evidence of arc growth is preserved in the Late Devonian-Early Cretaceous Median Batholith, a belt of intrusive rock whose growth culminated with the emplacement of the Western Fiordland Orthogneiss (WFO) into the middle-lower crust of the margin. Following this magmatic flare-up, the margin experienced Late Cretaceous extensional orogenic collapse and …

Evolution Of Off-Fault Deformation Along Analog Strike-Slip Faults, Alexandra E. Hatem

Masters Theses

Strike-slip faults evolve to accommodate more fault slip, resulting in less off-fault deformation. In analog experiments, the measured fault slip to off-fault deformation ratios are similar to those measured in crustal strike-slip systems, such as the San Andreas fault system. Established planar faults have the largest fault slip to off-fault deformation ratio of ~0.98. In systems without a pre-existing fault surface, crustal thickness and basal detachment conditions affect shear zone width and roughness. However, once the applied plate displacement is 1-2 times the crustal thickness, partitioning of deformation between fault slip and off-fault distributed shear is >0.90, regardless of the …

Low-Temperature Deformation Of Mixed Siliciclastic & Carbonate Fault Rocks Of The Copper Creek, Hunter Valley, And Mcconnell Thrusts, Jack R. Hoehn

Honors Papers

This study analyzes the low-temperature deformation of fault rocks associated thrust faults. Each fault has dominantly carbonate rocks in one wall and dominantly siliciclastic rocks in the other. The rocks from the Hunter Valley and Copper Creek thrusts of the Southern Appalachians, and McConnell thrust of the Canadian Rockies, were analyzed using data extracted at the thin section and SEM scale. The rocks, all of which featured a fine-grained carbonate matrix surrounding larger carbonate and siliciclastic carbonates, all experienced general shearing, but deformed by different deformation mechanisms. The Hunter Valley and McConnell samples showed evidence of cataclasis, diffusive mass transfer, …

Preliminary Investigation Of The Geometry And Kinematics Of The Bangong-Nujiang Suture At The Basu Metamorphic Massif, Se Tibet, Chase Michael Billeaudeau

LSU Master's Theses

There are many uncertainties associated with the development and deformation of the Tibetan Plateau. The Basu Massif, located along the eastern Bangong-Nujiang Suture Zone, is an ideal locality to help provide constraints to resolve the geologic evolution of the Tibetan Plateau. The Basu Massif is characterized by high pressure-ultra high pressure (HP-UHP) metamorphic rocks, syn- and post-collisional granites, and a central Upper Paleozoic unit bounded by discontinuous belts of serpentinite. Field data suggests that the carbonates of the central Upper Paleozoic unit, serpentinites, granites and metasedimentary rocks are part of an isoclinally folded shear zone that may have been thrust …

Pennsylvanian To Cretaceous Folds And Thrusts In South-Central Nevada: Evidence From The Timpahute Range, Angela Giovanna Russo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding Permian and Mesozoic contractional structures from southern California to northern Nevada requires correlation through south-central Nevada. After the Devonian-Mississippian Antler orogeny through the Permian-Triassic Sonoma orogeny and then up to the Sevier orogeny, south-central Nevada was thought to have remained tectonically inactive. However, Pennsylvanian through Jurassic age deformation is documented to the south in Death Valley and to the north. Identifying geometries, spatial relationships, and relative timing of deformations in the Timpahute Range, south-central Nevada, is an essential piece to completing the overall understanding of Nevada geology. The purpose of this study is to identify and analyze deformational structures …

Insights Into The Timing, Origin, And Deformation Of The Highland Mountains Gneiss Dome In Southwestern Montana, Usa, Lane Markes Boyer

Graduate Theses and Dissertations

The Highland Mountains of southwestern Montana offer a unique view of the Archean igneous and metamorphic rocks within the Great Falls tectonic zone (GFTZ). A Paleoproterozoic structural gneiss dome has been interpreted in the southern extent of the Highland Mountains. The ∼ 130km² of exhumed metamorphic rocks and gneiss dome exposed in the Highland Mountains are the primary focus of this research. The formation of the Highland Mountains gneiss dome is proposed to be directly related to a northwest-side down detachment (the Steels Pass shear zone) that formed during terrane collision along the GFTZ. The field investigation determined foliation …

Determining The Motion And Location Of The Frenchman Mountain Fault, Las Vegas, Nevada: A Paired Basin Analysis And Structural Analysis, Laura Margaret Eaton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding the evolution of large-scale fault systems remains a challenge to geologists and is of critical importance in understanding the dynamics of larger plate tectonic interactions. I mapped the southwestern Frenchman Mountain Fault (FMF), conducted a basin analysis of units in the footwall of the fault, and measured kinematic indicators along the fault zone in order to constrain fault offset, magnitude, and timing in an attempt to further our understanding of these systems.

My findings include: 1) the presence of vertical and sub-vertical slickenlines on southwest dipping fault surfaces indicative of normal sense offset; 2) relatively little lateral variation in …

Field-Based Constraints On The Origin Of The Benton Uplift, Ouachita Mountains, Rachel Victoria Keng

Graduate Theses and Dissertations

The Ouachita Mountains are an east-west trending fold-and-thrust belt exposed in west central Arkansas and southeastern Oklahoma. The Mississippian-Pennsylvanian Ouachita orogeny occurred when the Sabine arc terrane collided during south-facing subduction, during closure of the Cambrian passive margin of the North American plate. Deep-water Paleozoic strata were incorporated into an accretionary wedge as the Sabine terrane approached the North American plate. Folds and thrust faults in the Ouachita Mountains generally verge north due to tectonic transport of an accretionary wedge from south to north. Structures in the Benton and Broken Bow Uplifts (located in the core of the wedge) locally …

Deciphering Controls On Polyphase Intraplate Deformation In The Ertomiao Region, Lang Shan, North-Central China, Michael Blevins

LSU Master's Theses

The Ertomiao region of the Lang Shan, China, is located approximately 700 km west of Beijing, in the north-central portion of the North China block. This area is characterized by multiple periods of deformation, including periods of extension and contraction, spanning from Permian through Cenozoic time. This setting provides the structural relationships necessary to decipher the controls of polyphase crustal deformation. During fieldwork key structural observations and crosscutting relationships were established. Beginning with a period of contraction, northeast striking post Jurassic, pre Early Cretaceous (123 ma) thrust faults place Precambrian gneiss (unit PCB) onto Jurassic/Cretaceous sandstone and conglomerate (unit Jr/K). …

Geologic Map And Structural Analysis Of The Twin Rocks 7.5 Minute Quadrangle, Wayne County, Utah, Samuel C. Sorber

Theses and Dissertations

A new geologic map of the Twin Rocks 7.5 minute quadrangle primarily located within Capitol Reef National Park, south-central Utah, provides stratigraphic and structural detail not previously available. This map has also been instrumental in understanding the evolution and development of fluvial terraces associated with Sulfur Creek and the structural geology of the backlimb of the Miners Mountain uplift. Nine bedrock stratigraphic formations and eight types of Quaternary deposits were mapped throughout the quadrangle. Bedrock stratigraphy ranges in age from Permian to Jurassic. New details absent on previous geologic maps include members of the Chinle and Moenkopi Formations and the …

Field Relations, Structural Geology, And Geochemistry Of The Jonestown Volcanic Field, Lebanon County, Southeastern Pennsylvania, Tristan J. Ashcroft

Geology Theses and Dissertations

The Jonestown Volcanic Field is a five kilometer by fifteen kilometer area of volcanic and hypabyssal rocks, basalt and diabase, located in southeastern Pennsylvania. These igneous rocks presently occur within an allochthonous belt of Ordovician deep water sedimentary rocks and Taconic flysch rocks known collectively as the Hamburg Klippe. Detailed field mapping during this project has revealed that the contacts between the igneous rocks and the flysch are not conformable. The volcanic rocks are associated with the Ordovician limestone that is adjacent to these volcanics. This limestone also is not conformable to the Hamburg Klippe sediments, rather it shares outcrop …

Tertiary Stratigraphy And Structural Geology, Wellsville Mountains To Junction Hills, North-Central Utah, Kathryn M. Goessel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study integrates detailed mapping of Tertiary deposits along the divide between the lower Bear River basin and the Cache Valley basin with several other techniques to generate a depositional model, define extension-related structures, and compile a geologic history for this part of the northeastern Basin and Range province. The study area is situated along the topographic divide between Box Elder and Cache Counties, Utah, from the Wellsville Mountains north almost to Clarkston Mountain. These ranges are cored by folded and thrusted Paleozoic rocks. They are bound on the west by normal faults of the Wasatch fault zone and on …

Tectonic Denudation Of Mesozoic Contractile Structures By A Low-Angle Normal Fault And Associated Faults, Southern White Pine Range, Nevada, Holly Langrock

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Blackrock Canyon area in the southern White Pine Range, Nevada mostly consists of the highly extended upper plate of a low-angle normal fault, the Blackrock fault. The post-31.3 Ma Blackrock fault places upper Paleozoic sedimentary rocks and overlying Tertiary volcanic rocks of the Garret Ranch Group in its hangingwall against a 50 degrees E-dipping homocline of Cambrian through Mississippian rocks in its footwall. The 15 to 30 degrees W-dipping Blackrock fault is non-planar and consists of two fault segments and a pronounced corrugation, the Bull Spring corrugation. These geometric irregularities suggest the slip direction on the fault was east-southeast …

Gravity Maps, Models And Analysis Of The Greater Portland Area, Oregon, Paul Thomas Beeson

Dissertations and Theses

Growing concern over earthquakes in the Pacific Northwest has prompted the mapping and location of near surface faults in the Portland area, Oregon. Visible evidence of faults is poor, requiring the use of geophysical methods to assist in mapping and defining structures in the basin. Gravity maps and models may help in addressing this problem.