Geology Commons^™

Subsidence History Of The Rukwa Rift In South West Tanzania Analysed From Ivuna Well, E I Mbede

Tanzania Journal of Science

The variation in subsidence rate during rift basin development is a good indication for the Geodynamic history of a sedimentary basin. The sedimentary section of Ivuna Well is herein used to explain the structural evolution of Rukwa Basin within the Western Rift of the East African Rift System. The sedimentary record of Ivuna Well is extracted from published information. The effects of sedimentary load, corrected for compaction and variation in water depth, and lake-level have been removed to obtain the "tectonic subsidence." Curves show two phases of accelerated subsidence related to the fault controlled rifting phases: The Karoo rifting and …

Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird

Geology Faculty Publications

Published mechanisms for rift tip propagation at spreading centers include extensional deformation and an initial period of slow spreading. We investigate whether the gravity signal and inferred crustal structure at pseudofaults formed in medium to superfast spreading environments resemble the gravity signal at fracture zones or nontransform discontinuities formed in slow spreading environments. We find that altimetry-based gravity anomalies on the Mathematician, Bauer, Easter, Juan Fernandez, and northern Chile Ridge pseudofaults, located in 75–150 mm/yr (full rate) seafloor spreading environments, are similar in amplitude and form to Atlantic fracture zones with 20–30 mm/yr spreading rates. A 5–15 mGal positive mantle …

New Kinematic Models For Pacific‐North America Motion From 3 Ma To Present, Ii: Evidence For A “Baja California Shear Zone”, Timothy Dixon, Fred Farina, Charles Demets, Francisco Suarez-Vidal, John Fletcher, Bertha Marquez-Azua, M. Meghan Miller, Osvaldo Sanchez, Paul Umhoefer

All Faculty Scholarship for the College of the Sciences

We use new models for present‐day Pacific‐North America motion to evaluate the tectonics of offshore regions west of the Californias. Vandenburg in coastal Alta California moves at the Pacific plate velocity within uncertainties (∼1 mm/yr) after correcting for strain accumulation on the San Andreas and San Gregorio‐Hosgri faults with a model that includes a viscoelastic lower crust. Modeled and measured velocities at coastal sites in Baja California south of the Agua Blanca fault, a region that most previous models consider Pacific plate, differ by 3–8 mm/yr, with coastal sites moving slower that the Pacific plate. We interpret these discrepancies in …

Magmatic Processes Operating During The Middle To Late Pliocene And Pleistocene Along The Transition Zone Near 43º North, Christy L. Lee

Dissertations and Theses

A geochemical and structural transition zone exists between the Cascades and Basin and Range provinces in Oregon. Geologic mapping in this area has allowed the definition of six volcanic rock sequences: 1) interfingered alkali-rich basaltic trachyandesite to trachydacite lava flows and low-alkali basaltic andesite lava flows, 2) HAOT lava flows, 3) basaltic andesite lava flows, 4) andesite lava flows and vent deposits with minor basaltic andesite lava flows, 5) HAB lava flows, and 6) interfingered basaltic andesite, andesite, and trachyandesite lava flows.

Geochemical models of sequence 1 alkali-rich rocks suggest the fractionation of the parent assemblage plag (An₅₅)+magn+ol±aug …

Lava And Ice Interaction At Stratovolcanoes: Use Of Characteristic Features To Determine Past Glacial Extents And Future Volcanic Hazards, David T. Lescinsky, Jonathan H. Fink

Geology Faculty Publications and Presentations

Structures resulting from lava and ice interaction are common at glaciated stratovolcanoes. During summit eruptions at stratovolcanoes, meltwater is produced and travels freely down steep slopes and thin permeable valley glaciers, eroding the ice and enlarging preexisting glacial drainages. As a result, in this environment have produced few catastrophic floods. Lava flowing into the open channels and voids in the glaciers becomes confined and grows thicker, filling the available space and producing steep-sided bodies with smooth, bulbous contact surfaces. Quenching of lava against ice or by water forms small-scale features such as tensional fractures and glass. As the amount of …

Use Of Goes Thermal Infrared Imagery For Eruption Scale Measurements, Soufrière Hills, Montserrat, William I. Rose, Gari C. Mayberry

Department of Geological and Mining Engineering and Sciences Publications

GOES two-band IR data are used to estimate the magnitude of small eruption clouds (ash; <∼10⁵ tonnes of fine [1–25 µm in diameter] ash, and 5–15 km asl). The method is demonstrated on clouds from Soufrière Hills Volcano, Montserrat in 1997–99. The clouds in early 1999 were much smaller, were generally emplaced lower in the atmosphere and contained an order of magnitude less fine ash than 1997 clouds generated during the most intense phase of the eruption to date. Although GOES has an excellent capability for large eruption clouds, its use for smaller eruptions like Montserrat highlights several shortcomings, including …

Evolution Of The Kangmar Dome, Southern Tibet: Structural, Petrologic, And Thermochronologic Constraints, Jeffrey Lee, Bradley R. Hacker, William S. Dinklage, Yu Wang, Phillip Gans, Andrew Calvert, Jinglin Wan, Wenji Chen, Ann E. Blythe, William Mcclelland

All Faculty Scholarship for the College of the Sciences

Structural, thermobarometric, and thermochronologic investigations of the Kangmar Dome, southern Tibet, suggest that both extensional and contractional deformational histories are preserved within the dome. The dome is cored by an orthogneiss which is mantled by staurolite + kyanite zone metasedimentary rocks; metamorphic grade dies out up section and is defined by a series of concentric kyanite-in, staurolite-in, garnet-in, and chloritoid-in isograds. Three major deformational events, two older penetrative events and a younger doming event, are preserved. The oldest event, D1, resulted in approximately E-W trending tight to isoclinal folds of bedding with an associated moderately to steeply north dipping axial …

Field Trip Guide (For The Nebraska Well Drillers Association) Eastern Nebraska Geology, Scott Summerside, Duane Eversoll, Mark Kuzila, Matt Joeckel

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Arthur County Test-Hole Logs: Nebraska Water Survey Test-Hole Report No. 3, Robert F. Diffendal Jr., James W. Goeke

Robert F. Diffendal, Jr., Publications

In 1930, the Conservation and Survey Division (CSD) of the University of Nebraska and the United States Geological Survey began a program of cooperative groundwater studies in Nebraska. Since then test drilling by use of rotary drilling equipment has been an integral part of that program. This report contains logs of all the test holes drilled in Arthur County under the program as well as those drilled by the Conservation and Survey Division with financial assistance from other government agencies.

The maps in this report show the locations of all test holes drilled in the county since 1934.

Present techniques …

Effect Of The Direction Of The Blast On Vegetation Recovery Within The Zone Of Devastation Created By The May 18, 1980 Eruption Of Mount St. Helens, Washington, Dmitri Barkovsky

All-Inclusive List of Electronic Theses and Dissertations

A number of different remote sensing techniques were used to analyze Landsat TM image data in order to study vegetation recovery patterns at three locations within the zone of devastation of Mount St. Helens (MSH). Prior to the May 18, 1980 eruption, the vegetation in the area ofMSH was characterized by mature coniferous forest disturbed only by a few clearcuts, according to analysis of Landsat MSS data. As a result of the MSH eruption, more than 600 sq. km of the area predominantly north of the volcano were severely devastated by a number of volcanic events such as phreatic explosions, …

Comparative Analysis Of Thebes And Kirk Lithic Technology And Home Range Implications In Southwestern Indiana, Mark E. Cantin

All-Inclusive List of Electronic Theses and Dissertations

Early Archaic populations are typically characterized as highly mobile forager groups with expansive home ranges, though little distinction is made between systems of penecontemporaneous groups. This thesis will investigate and compare home range size, technology, and material type and quality selection practices between two Early Archaic populations as manifested by Kirk and Thebes Cluster projectile points in a data set recovered from southwestern Indiana. The mechanisms behind and the relationships between chert selection and mobility will be shown as a complex feedback loop. As such, the role of curation, embeddedness, and risk management in technological organization and the potential influence …

Keith County Test-Hole Logs: Nebraska Water Survey Test-Hole Report No. 51, Robert F. Diffendal Jr., James W. Goeke

Robert F. Diffendal, Jr., Publications

In 1930, the Conservation and Survey Division (CSD) of the University of Nebraska and the U.S. Geological Survey began a program of cooperative groundwater studies in Nebraska. Since then test drilling by use of rotary drilling equipment has been an integral part of that program. This report contains logs of all the test holes drilled in the county under the program as well as those drilled by the Conservation and Survey Division with financial assistance from other government agencies.

The maps in this report show the locations of all test holes drilled in the county since 1934 (Figure la–d).

Present …

Sedimentologic And Paleogeomorphologic Character Of The Western Beteiha Plain, Israel, Laura Baker

Student Work

The geographical problem addressed in this study was to reconstruct the paleogeography of the western Beteiha Plain, located between Bethsaida and the Sea of Galilee and determine its sedimentologic and paleogeomorphologic character. Grain size analysis of sediments, along with sediment color was used to reconstruct the landscape and identify areas such as estuaries or lagoons.

Sediment samples were collected throughout the Beteiha Plain at selected locations. Excavation and collection was accomplished with hand-driven core equipment and backhoe trenches.

The multidisciplinary approach used in this project included fieldwork for sediment collection, laboratory analysis for the production of the data necessary to …

Calibration Of Optical Digital Fragmentation Measuring Systems, Norbert H. Maerz, Wei Zhou

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Optical granulometry systems like WipFrag are required to measure fragments in situ. That is to say, the fragments are in piles where sorting takes place, where fragments are partially overlapped, and where fines may not be seen because they fall in and behind the coarser fragments, or where the fines are simply too small to be seen. As a result, optical systems tend typically to overestimate the size of the distribution, and underestimate the variability of the distribution. The wider the size distribution being measured, the more severe the problem is. This paper presents the results of a study that …

Establishing The Inundation Distance And Overtopping Height Of Paleotsunami From The Late-Holocene Geologic Record At Open-Coastal Wetland Sites, Central Cascadia Margin, Robert B. Schlichting

Dissertations and Theses

Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Cascadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast.

Anomalous sand sheets that have been characterized …

Debris-Flow Activity In Canyon Of Lodore, Colorado: Implications For Debris-Fan Formation And Evolution, Jennifer A. Martin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Large-scale characteristics of Ladore Canyon debris fans are dependent upon the bedrock and lithology of the mainstem and tributary canyons. The largest fans occur in the widest section of the mainstem canyon, which typically correlates with the location of large faults. The steepest fans are found at the mouths of tributaries where cliffs are formed by resistant lithologies. Smaller-scale fan characteristics are dependent upon the magnitude and frequency of events from the respective drainage basin, which is controlled primarily by climate. Three distinct deposit ages (oldest, intermediate, youngest) were distinguished on individual fans and were tentatively correlated throughout the canyon …

The Sequence Stratigraphy Of The Middle Cambrian Wheeler Formation In The Drum Mountains Of West Central Utah, Loren P. Schneider

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The majority of the Middle Cambrian Wheeler Formation in the Drum Mountains was deposited during a single 3^rd order sequence. Superimposed onto this sequence are three indistinct 4^th order cycles and twenty distinct 5^th order cycles. These higher order cycles were likely deposited within short intervals of geologic time (204 to 405 ky).

The lower sequence boundary zone occurs within the Swasey Formation. The Transgressive Surface is the contact between the Swasey and Wheeler Formations. The Maximum Flooding Surface is located near the top of the lower Wheeler Formation, which also approximates the base of the Ptychagnostus …

Holocene Tephrostratigraphy, Southern Kenai Peninsula, Lower Cook Inlet, Alaska, Kathleen J. Lemke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis describes the results of a study of 33 tephra layers found within two peat sections near Anchor Point and Homer, Alaska, on the lower Kenai Peninsula. Numerous lower Cook Inlet volcanoes have been active through the Holocene. Tephra layers found at these two sites provide a partial record of their eruptive activity. The hazards that accompany this activity have increased as populations and commercial activities expand and air traffic over the region increases. The tephras analyzed for this study provide an initial geochemical database for the lower Cook Inlet volcanoes. The database is available in electronic format at …

Late Quaternary Glacier Fluctuations And Vegetation Change In The Northwestern Ahklun Mountains, Southwestern Alaska, Yarrow L. Axford

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research examines moraine and lacustrine records of glacier fluctuations, in combination with palynological records of vegetation change, from the previously unstudied northwestern Ahklun Mountains in southwestern Alaska.

Moraine mapping reveals that ice-cap outlet glaciers in the study area extended ca. 60 km from the center of the Ahklun Mountians ice dome during the early Wisconsin (sensu lato), and ca. 40 km during the late Wisconsin. Correlations with well-studied moraines in the southern Ahklun Mountains indicate an asymmetry of glaciation over the range, with ice-cap outlet glaciers more extensive to the south. This asymmetry was more striking during …

The Age Of The Woolly Rhino From Dream Cave, Derbyshire, Uk, Donald A. Mcfarlane, Joyce Lundberg, Derek C. Ford

WM Keck Science Faculty Papers

The Dream Cave woolly rhinoceros, Coelodonta antiquitatis, is a "classic" specimen of a "cold-stage" fossil fauna from central England. The find was illustrated and described by Dean William Buckland in his seminal tome Reliquiae Diluvianae (1823) during the first half of the 19th century, and made a significant contribution to the development of Buckland's views on the origin of extinct and extirpated fossil vertebrates. The report presents the first, albeit indirect, radiometric dates on the specimen, and argues that the animal fell into the cave just before 37,000 years BP, during the middle of Marine Isotope Stage 3 Interstadial (41 …

Sedimentology, Palynology, And Sea Level Fluctuations Recorded From Two Pennsylvanian Cores From Northwestern Missouri, Elizabeth J. Morris, Francisca Oboh-Ikuenobe

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Two cores from Buchanan and Andrew Counties in the Forest City Basin, northwestern Missouri, yielded approximately 1,200 feet of sedimentary rock deposited during the Pennsylvanian Period (approximately 300 million years ago), a period characterized by rapid fluctuations in sea level. The cores were logged from the Excello Formation in the Upper Desmoinesian Series upward to the Iatan Formation at the top of the Missourian Series. Lithofacies were identified from rock composition, grain size, color, bedding thickness, sedimentary structures, and fossils. Petrographic thin sections were taken from selected rock types and the results were used to complement the visual descriptions. Limestones …

Field Trip Guide For The Upper Republican And Middle Republican Nrd's Southwestern Nebraska Geology And Soils, Duane Eversoll, Jim Goeke, Mark Kuzila

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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 …

Present‐Day Motion Of The Sierra Nevada Block And Some Tectonic Implications For The Basin And Range Province, North American Cordillera, Timothy H. Dixon, M. Meghan Miller, Frederic Farina, Hongzhi Wang, Daniel Johnson

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) data from five sites on the stable interior of the Sierra Nevada block are inverted to describe its angular velocity relative to stable North America. The velocity data for the five sites fit the rigid block model with rms misfits of 0.3 mm/yr (north) and 0.8 mm/yr (east), smaller than independently estimated data uncertainty, indicating that the rigid block model is appropriate. The new Euler vector, 17.0°N, 137.3°W, rotation rate 0.28 degrees per million years, predicts that the block is translating to the northwest, nearly parallel to the plate motion direction, at 13–14 mm/yr, faster than …

Creating Virtual 3-D Outcrop, Xueming Xu, Carlos L. V. Aiken, Janok P. Bhattacharya, Rucsandra M. Corbeanu, Kent C. Nielsen, George A. Mcmechan, Mohamed G. Abdel Salam

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Because of the high precision of present-day GPS and reflectorless laser technology, geologic information and remotely sensed data (i.e., seismic and GPR grids, wells) can be positioned accurately in 3-D and reconstructed as a virtual image. Hence, we have developed the “virtual outcrop” for applications that require knowledge about the 3-D spatial arrangements of rock types.

Lower Elkhorn Natural Resources District Cooperative Agreement, Field Summary Report 1998-1999, Susan Olafsen Lackey

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Upper Elkhorn Natural Resources District Cooperative Agreement, Field Summary Report 1998-1999, Susan Olafsen Lackey

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Feature Extraction In Geobiophysical Modeling Of Mining Activity Impacting Dewey Lake, Kentucky, Sean K. Litteral

Theses, Dissertations and Capstones

Surface coal mining activity has effects on watershed and lake morphology within the Appalachian Mountains that continue to be problematic. A watershed’s natural dynamic balance has been subject to the influence of various natural and anthropogenic parameters such as mining sediment transport, wind, wave effects and currents. Many techniques have been developed to improve image processing in geobiophysical modeling, which can assist scientists, government officials, and industry personal with decisions affecting environmental concerns. One of the more advanced techniques involves 3D visualization and geobiophysical modeling. This process was used in combining remotely sensed digital aerial imagery with Digital Elevation Models …

The Microstratigraphy Of The Meadville Member Of Lodi, Northeastern Ohio: A Lithofacies Analysis, Andrew S. Madof

Honors Papers

During the Lower (Osagian) Mississippian Period, Ohio was about 7 degrees south of the equator in a tropical epicontinental sea at the northwestern edge of the Appalachian foreland Basin. Present day Lodi, northeastern Ohio, lay within the midst of a westward deepening syncline whose sediment was derived from the Acadian uplifts to the east. This sediment, composed primarily of illite and quartz, was deposited about 100 m below sea level in a middle to outer deltaic environment. From the base (Meadville Member) to the top (Armstrong Member) of the strata exposed at Lodi, a general increase in grain size occurs. …

Reflections Of A Naturalist: Papers Honoring Professor Eugene D. Fleharty, Jerry R. Choate

Fort Hays Studies Series

Science and academia tend to be dominated by persons who are utterly brilliant, or who are proficient at self-promotion, or who are willing to sacrifice their personal lives and work twice as hard as their peers, or who exhibit some combination of these attributes. Occasionally, however, someone comes along who is just "ordinary" compared with academic overachievers but whose accomplishments far exceed reasonable expectations. Eugene D. Fleharty is such a person. Although he is extraordinarily bright, few would describe him as utterly brilliant. He has never been inclined to "toot his own horn" or otherwise promote himself. And, although he …