Physical Sciences and Mathematics Commons^™

Origins Of Low-Angle Normal Faults Along The West Side Of The Bear River Range In Northern Utah, Jon E. Brummer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This paper presents new interpretations of two normal-slip, low-angle faults near Smithfield and Richmond, Utah. The faults have previously been interpreted as landslides, gravity slides, slide blocks, and depositional contacts. Recent work in the Basin and Range province allows new interpretations concerning the origins of the low­-angle faults.

Working hypotheses used to interpret origins of the faults are classified as folded thrust fault, rotated high-angle normal fault, gravity slide, listric normal fault, and low-angle normal fault. Among these general categories are several subhypotheses. The evaluation of each hypothesis includes a description of the geologic requirements of the hypothesis, a comparison …

Elemental Relationships In Rock Varnish As Seen With Scanning Electron Microscopy And Energy Dispersive X-Ray Elemental Line Profiling, Robert Raymond Jr., Steven L. Reneau, Charles D. Harrington

Scanning Microscopy

The heterogeneous nature of rock varnish requires a thorough understanding of elemental and mineralogic compositions before chemical variability of rock varnish may be confidently related to varnish age or to past geochemical environments. Elemental relationships in rock varnish were examined using scanning electron microscopy in conjunction with an elemental line profiling routine using semi-quantitative, energy-dispersive x-ray analysis. Results of our analyses suggest: 1) variations in cation concentrations used in varnish cation-ratio dating relate more specifically to variations in detritus concentration within the varnish than to element mobility as defined by weathering indices; 2) Mn:Fe ratios may be a poor indicator …

Scanning Electron Microscopic Analysis Of Rock Varnish Chemistry For Cation-Ratio Dating: An Examination Of Electron Beam Penetration Depths, Steven L. Reneau, Roland C. Hagan, Charles D. Harrington, Robert Raymond Jr.

Scanning Microscopy

Rock varnish is a microns-thick manganese- and iron-rich coating that forms on exposed rock surfaces in arid and semi-arid environments, and empirical correlations of the varnish cation ratio (K+Ca):Ti with age have been used to estimate ages of geomorphic surfaces. One method of obtaining varnish chemistry for cation-ratio dating involves scanning electron microscope (SEM) energy dispersive x-ray (EDX) analysis of natural varnish surfaces. The chemical analyses of rock varnish with SEM/EDX utilize a sequence of accelerating voltages to vary penetration depths into the sample. Using elemental x-ray maps of natural varnish surfaces obtained by SEM/EDX analysis, penetration into the substrate …

Barium Concentration In Rock Varnish: Implications For Calibrated Rock Varnish Dating Curves, C. D. Harrington, D. J. Krier, R. Raymond Jr., S. L. Reneau

Scanning Microscopy

Cation-ratio dating of rock varnish is a recently developed technique for obtaining surface exposure ages of a wide variety of geomorphic surfaces. As originally proposed, the technique utilizes a ratio among minor cations [(K+Ca)/Ti] in rock varnish. Although this varnish cation ratio is related to the Ti concentration, it can also be affected by the presence of Ba that may be partially included in the analyzed concentration of Ti. Barium is a minor constituent found in virtually all rock varnishes sampled from the Lake Mead area, Las Vegas Valley, and the Crater Flat region of southern Nevada. Barium is heterogeneously …

Flood Insurance Study, City Of Bountiful, Utah, Davis County, Federal Emergency Management Agency

All U.S. Government Documents (Utah Regional Depository)

This Flood Insurance Study revises and updates a previous Flood Insurance Study/Flood Insurance Rate map for City of Bountiful, Davis County, Utah. This information will be used by the City of Bountiful to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP). The information will also be used by local and regional planners to further promote sound land use and floodplain development.

Wyoming Statewide Wilderness Study Report, Wilderness Study Area Specific Recommendations, Volume Ii, United States Bureau Of Land Management

All U.S. Government Documents (Utah Regional Depository)

The WSA was studied under section 603 of the Federal Land Policy and Management Act of 1976 (FLPMA) and was included in the Grass Creek/Cody Wilderness Environmental Impact Statement (EIS) filed in August 1990. There were two alternatives analyzed in the EIS, No Wilderness and All Wilderness. The All Wilderness Alternative is the recommendation of this report.

Constraints On Unroofing Rates In The High Himalaya, Eastern Nepal, Mary S. Hubbard, L. H. Royden, K. V. Hodges

Geosciences Faculty Publications

Thermobarometric data for samples across the Main Central thrust zone in eastern Nepal show an inversion in temperature but not in pressure. These data have been interpreted to represent a portion of the paleogeotherm at the time of Main Central thrust deformation. A 40Ar/39Ar age on hornblende (closure temperature (Tc)=500±50°C) constrains the timing of this deformation to be ∼21±0.2 Ma. The 40Ar/39Ar ages of other minerals (muscovite, Tc=350°C, age (t)=12.0±0.2 Ma; K-feldspar, Tc=220°C, t=8.0±0.2 Ma) from the same location further constrain the cooling history of this region. Together the geochronologic and thermobarometric data yield an average unroofing rate of 1.2±0.6 …

Hydrogeology Of Thrust Faults And Crystalline Thrust Sheets: Results Of Combined Field And Modeling Studies, Craig B. Forster, James P. Evans

Geosciences Faculty Publications

Field, laboratory, and modeling studies of faulted rock yield insight into the hydraulic character of thrust faults. Late‐stage faults comprise foliated and subparallel faults, with clay‐rich gouge and fracture zones, that yield interpenetrating layers of low‐permeability gouge and higher‐permeability damage zones. Laboratory testing suggests a permeability contrast of two orders of magnitude between gouge and damage zones. Layers of differing permeability lead to overall permeability anisotropy with maximum permeability within the plane of the fault and minimum permeability perpendicular to the fault plane. Numerical modeling of regional‐scale fluid flow and heat transport illustrates the impact of fault zone hydrogeology on …

Surficial Geologic Map Of The Oak City Area, Millard County, Utah, United States Geological Survey

All U.S. Government Documents (Utah Regional Depository)

This map is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature.