Physical Sciences and Mathematics Commons^™

Micro- To Macro-Scale Structural And Lithological Architecture Of Basal Nonconformities: Implications For Fluid Flow And Injection Induced Seismicity, Garth Hesseltine

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rising incidents of earthquakes caused by human activity in the United States, known as induced earthquakes, is a growing concern. Induced earthquakes may occur when fluid and/or wastewater is injected several kilometers beneath the Earth’s surface into sedimentary rocks. Fluids and pressures can migrate from the sedimentary rocks, which are typically friendlier to fluid flow, into underlying less friendlier crystalline rocks along fluid pathways weakening and possibly reactivating preexisting faults. Understanding potential fluid pathways and/or barriers from the sedimentary rocks to crystalline rocks is crucial. I investigate the structure, composition, and heterogeneity of rocks near the contact between the sedimentary …

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 …

Composition, Microstructures, And Petrophysics Of The Mozumi Fault, Japan: In Situ Analyses Of Fault Zone Properties And Structure In Sedimentary Rocks From Shallow Crustal Levels, Angela J. Isaacs, James P. Evans, Peter T. Kolesar, Tsuyoshi Nohara

Geosciences Faculty Publications

[1] We characterize the chemical, microstructural, and geophysical properties of fault-related rock samples from the 80–100 m wide Mozumi fault zone, north central Honshu, Japan. The fault is exposed in a research tunnel 300–400 m below the ground, and we combine geological data with borehole geophysical logs to determine the elastic and seismic properties of the fault zone. Detailed mapping within the tunnel reveals that the fault zone consists of two zones of breccia to foliated cataclasites 20 and 50 m thick. Two narrow (tens of centimeters wide) principal slip zones on which most of the slip occurred bound the …

Hydrologic Properties And Structure Of The Mozumi Fault, Central Japan, Craig B. Forster, James P. Evans, Hidemi Tanaka, Ronald Jeffreys, Tsuyoshi Nohara

Geosciences Faculty Publications

Analyses of rocks from the Active Fault Survey Tunnel (AFST) provides insight into the structure and hydrogeology of the northeast-trending Mozumi-Sukenobu fault, an active strike-slip fault with 125 to 500 m of right-lateral slip in central Japan. Interlayered regions of sub-vertical permeability zones formed by cataclasis and slip on clay-rich foliated zones. Core samples range from 10⁻¹⁹ m² to almost 10⁻¹³ m². CFC analyses of waters from the fault zone show that water entering the tunnel is 27–36 years old, yielding a bulk fault permeability of 10⁻¹⁴ to 10⁻¹⁵ m². The …

Structure And Petrology Of Tertiary Volcanic Rocks In Parts Of Toms Cabin Spring And Lucin Nw Quadrangles (Box Elder Co.), Utah, Bruce Edward Scarbrough

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A series of late Tertiary rhyolitic and dacitic flows, domes, and minor pyroclastic rocks form an elongate volanic mass along the northwestern Utah-northeastern Nevada border. The structure of the flow banding and the linear arrangement of vents indicate that the mass represents a multi-sourced extrusive complex which erupted through many fissure-type conduits. A 39 km² area at the southern end of the mass was studied in detail in order to gain a better understanding of the eruptive nature and history of these Tertiary volcanic rocks. Age dating reveals that volcanism in the study area was episodic, and covered a …

Structure And Petrography Of The Tertiary Volcanic Rocks Between Death Creek And Dairy Valley Creek (Box Elder Co.), Utah, E. Matthew Hare

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Several volcanic flows lie between Death Creek and Dairy Valley Creek, near Etna, Utah. The major, central portion of the volcanic flows is composed of dacite and dacite vitrophyre. An elongate ridge in the southeastern corner of the study area and several small outcrops in Death Creek Valley are composed of rhyolite and rhyolite vitrophyre. Additional rock types include conglomerate, volcanic ash, and tuffaceous sedimentary rock of the Tertiary Salt Lake Formation, Paleozoic limestone, and Tertiary basalt.

Dacite and dacite vitrophyre samples are porphyritic, containing phenocrysts of plagioclase, quartz, biotite, amphibole, orthopyroxene, and iron-titanium oxides. Rhyolite and rhyolite vitrophyre samples …

Structure And Petrology Of Tertiary Volcanic Rocks Near Etna, Utah, Kent W. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three volcanic domes and related volcanic rocks of Tertiary age are located near Etna, Utah, in Box Elder County. The domes follow a north-south trend and are fault controlled. Flow structure indicates a change from a less viscous, flow-forming lava which produced an exogenous dome to a more viscous lava which formed endogenous domes. Associated pyroclastic deposits are negligible. The volcanic rocks are composed of porphyritic rhyolite and rhyolitic vitrophyre having phenocrysts of quartz, sanidine, plagioclase and biotite with minor amounts of Fe-Ti oxides, hypersthene, allanite and calcic amphibole. Quartz and sanidine phenocrysts are generally embayed whereas plagioclase phenocrysts are …

Structural Geology Of The Southern Part Of Elkhorn Mountain, Bannock Range, Idaho, George A. De Vries

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The area of southern Elkhorn Mountain, a previously unmapped area, is located north of Malad City, Idaho, in the Bannock Range. The mapped area is within the Basin and Range province. The mapped area measures 5.9 miles in the north-south direction and approximately 8.8 miles in the east-west direction.

The oldest stratigraphic unit, in the mapped area, is the Ute Formation of Middle Cambrian age. Other units of Cambrian age, in ascending order, are: Blacksmith Formation, Bloomington Formation, Nounan Formation, and St. Charles Formation. The units of Ordovician age are the Garden City and the Swan Peak Formations. The youngest …