Tectonics and Structure Commons^™

Modeling The Greenland-Iceland-Faroe Ridge Using Integrated Geophysical Analysis, Zachary Clowdus

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Greenland-Iceland-Faroe Ridge (GIFR) is an area of significant geologic interest with anomalously thick crust related to enhanced melt generation from the interaction between the Mid-Atlantic Ridge and the Iceland hotspot. To the northeast of Iceland lies the Jan Mayen Microcontinent (JMMC), which is a continental fragment separated from Greenland during the opening of the Northern Atlantic. The overall extent of the JMMC, especially its southern boundary, remains poorly constrained. The crust beneath the GIFR is believed to be primarily of oceanic affinity. However, a recent discovery of felsic lavas in Iceland led to an alternative hypothesis that implies the …

Survey Of A Paired Gravity Anomaly Within The Benton Uplift Of The Ouachita Mountains, Isaac B. Prud'homme

Physics Undergraduate Honors Theses

The Benton Uplift west of Hot Springs, AR is underlain by a paired gravity anomaly on the order of 80 mGal. Nicholas & Rozendal (1975) have theorized that the gravitational low is caused by a “downwarp of the crust into the mantle”1 however the cause of the gravitational high is still debated. This paired gravity anomaly within the Benton Uplift follows the Ouachita orogenic belt southwest for 500 miles where it meets the Marathon uplift in southwest Texas. We conducted a gravity survey along a 108-km-long transect east of two previous gravity surveys.2,3 We corrected the data from this transect …

Integrated Geophysical Modeling Of Newly Identified Pseudofaults Within Southern Cascadia Subduction Zone, Morgan R. Madsen

Honors Program: Senior Projects (Public)

The Cascadia Subduction Zone, located off the western coast of North America, has a long history of seismic activity, causing various geohazards such as megathrust earthquakes and tsunamis for the coastal population (Goldfinger et al., 2000; Tréhu et al., 2022). It is necessary to identify areas of greater risk, as seismic hazards will continue to affect the area due to ongoing subduction of the oceanic Juan de Fuca plate beneath the North American continent. Heavily fractured, weakened zones of oceanic crust, known as propagator wakes and pseudofaults, have been shown to correlate with greater seismicity (Ashraf and Filina, 2023a). Propagator …

Gravity And Magnetic Analysis Of The Amu Darya Basin Of Turkmenistan And Uzbekistan, Logan R. Rogers

Graduate Theses/Dissertations

The Jurassic-Tertiary Amu Darya Basin is mainly located within Turkmenistan and Uzbekistan with a small portion extending into Afghanistan and Iran. The basin is one of the largest petroleum systems in central Asia. The basin is located in the southeast corner of the Turan platform, where both the Middle Paleozoic Turkestan and Early Mesozoic Tethys oceans were closed during different orogenies. The southern boundary of the basin is along the Bande Turkestan fold belt, the Afghan-Tajik basin to the east, Paleozoic metamorphic terranes to the north, and the Karakum high (Paleozoic basement rocks) to the west. Several blocks and terranes …

Processing Seismic, Gravity And Magnetic Data Over Diebold Knoll On Juan De Fuca Plate, Md Ariful Islam, Irina Filina

UNL Student Research Days Posters, Graduate

The Juan de Fuca plate is subducting beneath the North American plate along the Cascadia Subduction Zone. The CSZ is associated with multiple earthquakes, although compared to other subduction zones, it is less active. Many studies suggest that subduction will cause major mega thrust earthquake in near future, while others oppose this view. This project is focused on the Diebold Knoll on the JdF plate Various geophysical methods will be integrated to determine its origin and tectonic history.

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 …

Geophysical Analysis Of The Midcontinent Rift’S Subsurface Structure In Southeastern Nebraska, Patrick Szopinski

Honors Program: Senior Projects (Public)

The Midcontinent Rift System (MCRS) is a 1.1 billion-year-old failed rift system that spans much of the North American continental interior. The MCRS is exposed at Lake Superior and is buried in the subsurface along its southwest-extending arm through southeastern Nebraska. Due to the presence of buried volcanic rocks, the MCRS has characteristic highly-pronounced potential field anomalies (gravity and magnetic). Despite these large anomalies, not much is known about the subsurface faulting associated with the rift zone in the Midwest. The goal of this project is to attempt to use integrated analysis of collected geophysical data from multiple methods to …

Integrated Geophysical Analysis In The Northeastern Gulf Of Mexico, Mei Liu

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The formation of the Gulf of Mexico (GoM) relates to the breakup of Pangea and opening of the central Atlantic Ocean. The tectonic history of the basin is still being debated due to lack of geological constraints. This project addresses the crustal architecture in the northeastern GoM from integrative analysis of multiple geophysical datasets to provide constraints for the tectonic reconstruction.

The objectives of this study are: 1) to delineate various tectonic zones (continental and oceanic domains) and map the boundary between them, 2) to derive physical properties of the subsurface rocks, 3) to map the major tectonic structures in …

Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham

Theses and Dissertations--Earth and Environmental Sciences

A zone of high magnetization along the SE margin of Paleoproterozoic Laurentia in the United States is indicated by magnetic anomaly data. The SE edge corresponds to the geochemical Neodymium mantle derivation model age (T_DM) boundary and the entire anomaly overlies the Paleoproterozoic Mazatzal Province. Two-dimensional gravity and magnetic models across the Nd boundary are created with Moho constrained from receiver functions with gravity, sedimentary thickness and the base of the crustal magnetization. Upper crustal magnetization does not show strong variation across this boundary and much of the strong magnetization appears to lie in the middle crust. Using …

Spatiotemporal Slip Rate Variations Along Surprise Valley Fault In Relation To Pleistocene Pluvial Lakes, Brian N. Marion

All Master's Theses

Using mapped paleoshoreline features with high-resolution topographic data and obtained radiocarbon dates on paleoshoreline tufas, I documented precise fault offsets of dated features over the last 25 ka along the Surprise Valley Fault (SVF). Fault offset measured in three lake sections within Surprise Valley ranged from 3.6 m in the southern section to 14.4 m in the central section. The offset paleoshorelines are dated to the late Pleistocene (<22 >ka) and were formed during the latest impoundment of pluvial Lake Surprise since the last glacial maximum. Slip rates vary along strike, assuming a fault dip of 68° with 0.25 ± …

Spatial Scaling Of Crustal And Lithospheric Deformation In The Western United States, Cody W. Bomberger

Graduate Student Theses, Dissertations, & Professional Papers

Deformation of continental lithosphere can extend great distances laterally from tectonic plate boundaries. This extent has been used to argue for a variety of constitutive laws for continental materials, based on the underlying principles in continuum mechanics that identify a relationship between characteristic spatial scale and material properties. Although the relationship between observed deformation and material models is always non-unique, quantifying one or more characteristic scales of deformation in a region can rule out some models of how the lithosphere deforms. In the western United States active deformation occurs at the plate boundary between North America and either the Pacific …

Present Day Kinematics Of The Eastern California Shear Zone From A Geodetically Constrained Block Model, S. C. Mcclusky, S. C. Bjornstad, B. H. Hager, R. W. King, B. J. Meade, M. Meghan Miller, F. C. Monastero, B. J. Souter

All Faculty Scholarship for the College of the Sciences

We use Global Positioning System (GPS) data from 1993–2000 to determine horizontal velocities of 65 stations in eastern California and western Nevada between 35° and 37° N. We relate the geodetic velocities to fault slip rates using a block model that enforces path integral constraints over geologic and geodetic time scales and that includes the effects of elastic strain accumulation on faults locked to a depth of 15 km. The velocity of the Sierra Nevada block with respect to Nevada is 11.1±0.3 mm/yr, with slip partitioned across the Death Valley, (2.8±0.5 mm/yr), Panamint Valley (2.5±0.8 mm/yr), and Airport Lake/Owens Valley …

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) results from networks spanning the Eastern California shear zone and adjacent Sierra Nevada block, occupied annually between 1993 and 1998, constrain plate margin kinematics. We use an elastic block model to relate GPS station velocities to long‐term fault slip rate estimates. The model accounts for elastic strain accumulation on the San Andreas fault, as well as faults of the Eastern California shear zone. South of the Garlock fault, 14 mm/yr of dextral shear is distributed across the Eastern California shear zone. Some of this slip penetrates eastward into the Basin and Range, and a collective budget …

A Detailed Economic Investigation Of Geochemical And Aeromagnetic Anomalies North Central Maine, W. F. Stickney, R. S. Young, L. A. Wing

Maine Collection

A Detailed Economic Investigation of Geochemical and Aeromagnetic Anomalies North Central Maine

W.F.Stickney, R.S.Young and L.A.Wing

Special Economic Series No.4, Maine Geological Survey, Department of Economic Development, Augusta, Maine (March 1965).

Contents: Foreword / Part I - Geology (W.F. Stickney) / Part II - Geophysics (R.S. Young) / Part III - Geochemistry (L.A. Wing) / References

An Aeromagnetic And Geologic Reconnaissance Survey Of The Sidney - Augusta And Gardiner Areas : Kennebec County, Maine, Lawrence A. Wing

Maine Collection

An Aeromagnetic and Geologic Reconnaissance Survey of the Sidney - Augusta and Gardiner Areas : Kennebec County, Maine

(GP & G Survey #5)

by Lawrence A. Wing, Chief Geologist, James W. Sewall Company, Old Town, Maine.

Maine Geological Survey, Department of Economic Development, Augusta, Maine - August 12, 1959.