The Little Grand Wash fault and the Salt Wash Graben in the Colorado Plateau of southeastern Utah emit CO2 gas from abandoned drillholes, springs, and a hydrocarbon seep. Similar CO2-charged water has also been emitted in the past, as shown by large localized travertine deposits and veins along and near the fault traces. The faults cut natural CO2 reservoirs and provide an excellent analog for geologic CO2 sequestration. The faults cut a north-plunging anticline of rocks consisting of siltstones, shales, and sandstones from the Permian Cutler Formation through the Cretaceous Mancos Shale. The Little Grand Wash fault has 260 m of throw and the stratigraphic separation across the Salt Wash Graben is 50 m. The fault rocks in the damage zone show hundreds of fractures, which decrease in density farther away from the faults. In specific areas, fractures with the presence of calcite mineralization indicate fluid migration and bleach zones from a few millimeters to 30 cm. This is evidence of past fluid migration directly associated with the fault zone. Calcite mineralization fills these fractures and is also deposited in a variety of other bed forms. Foliated fault gouge, 5 to 20 cm thick, forms clay smear structures with a scaly shear fabric in a zone l0 to 15 cm thick is seen in the fault core. The leakage is constrained to the footwalls of the northernmost faults throughout the area. Clay-rich gouge structures should be effective barriers to cross-fault flow . Well log, surface geologic, and geochemical data indicate that the CO2 reservoirs have been cut by the faults at depth, providing a conduit for the vertical migration of CO2 to the surface, but not for horizontal flow across the fault plane. Even though lateral cross-fault migration may be impeded, this study clearly indicates that there are possible migration pathways for the escape of CO2 from faulted subsurface aquifers, including aquifers faulted by "low-permeability" faults with clay gouge. Three-dimensional flow models show how the fault's maximum permeability in the damage zone is parallel to the faults, and the leakage though the damage zone is localized near the fold axis of the regional anticline. Direct dating of the clay in the fault gouge was done by ExxonMobil with 40Ar/39Ar methods, indicating that fault movement occurred between the middle Eocene and the end of the Miocene. During this time, the Colorado Plateau is interpreted to have been experiencing rapid uplift. The middle Jurassic, upper Jurassic, and Cretaceous rocks at the surface have been uplifted approximately 1.8 km since the end of the Eocene. This uplift may have influenced fault movement in the Colorado Plateau and along the Little Grand Wash fault, and Salt Wash and Ten Mile Graben. In evaluating these deep aquifers for CO2 sequestration, careful design and monitoring of the geological structure and stress regimes must be considered to avoid leakage.

This dissertation encompasses two studies: one developing virtual field trips for mobile devices for an innovative approach to lower-division geoscience education, and the other examining the role of rock strength in river erosion and landscape evolution. The education study involves the development of three virtual field trip modules (Geologic Time, Geologic Structures, and Hydrologic Processes, all free on iTunes and Google Play) that lead students down a virtual Colorado River through Grand Canyon by physically moving around their campus quad, football field or other location, using their GPS-equipped smart phone or tablet. As students reach each location in the scaled down and geo-referenced virtual Grand Canyon, an informative video appears with a themed geological question and an interactive touchscreen activity. The effectiveness of these three modules in terms of student engagement and learning was tested at five U.S. Colleges with a range of missions and student demographics. Results show that the virtual field trip modules are effective at increasing student interest across races and genders in the geosciences, do not detract from student learning, and have the potential to increase content comprehension. The second study is the examination of the relation between rock strength and topography in the Colorado Plateau. This work contributes empirical data to the age-old debate over the mechanisms and patterns of stream erosion through statistical relations between rock strength and stream power, river steepness, and valley width along the Green-Colorado River system. Estimates of an “effective” tensile strength were calculated for units too incompetent to test directly, such as the shales prevalent in the region. Results indicate bedrock strength is a first-order control on river erosion in this landscape, as suggested by John Wesley Powell in 1896: “where the rocks are firm and stable, corrasion [sic] of the stream is slow; where the rocks are soft, corrasion [sic] is more rapid,” which is intuitive yet frequently overlooked.

Sixteen stands representing a range of structural variation in aspen, mixed aspen-conifer, and spruce-fir communities of the Wasatch Plateau, Utah, were censused by the sample count method. The stands were classified as eleven community types based on the understory dominants or indicator species and the cover types. Fifty bird species were recorded during the two seasons; thirty-two occurred in aspen cover, forty-four in mixed aspen-conifer cover, and twenty-two in spruce-fir. Comparisons of the composition and density of bird populations were made between uniform stands of a single life form and more structurally complex stands of either single or mixed life forms. Limiting factors in the structural characteristics of the stands were identified for birds restricted to particular stands. Low avian similarities between some aspen stands were attributed to the differences in structure between the stands. Bird species which favored the deciduous life form tended to decrease in abundance in the mixed stands as the canopy coverage of conifers increased, and they were absent in the spruce-fir stand. Coniferous forest bird species were more abundant in mixed stands with high coniferous coverage than in the aspen-dominated stands. Low individual bird numbers were found in the conifer stand of uniform small trees. Several vegetational characteristics of the stands were evaluated to determine if any was an index of forest heterogeneity predictive of bird species diversity. The habitat features of ecological relevance to most of the bird species were the size, spacing, and life form of the trees. The diversity of the distribution of diameter measurements at breast height for the tree species was predictive of bird species diversity. High diversity in the distribution of tree measurements at breast height was correlated with variation in tree height, tree canopy diameter, and the spacing of the life forms. It was therefore an index of three dimensional environmental patchiness, easily visualized by the variation in life forms and the number of stories within the stand.

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) are a sagebrush obligate species and as such an indicator of sagebrush (Artemisia spp.) habitat quality and quantity. Sage-grouse populations have declined across western North America. This decline has been attributed to habitat loss and degradation of the sagebrush ecosystem. To determine factors that may cause localized declines in sage-grouse populations, managers may need site-specific information on the ecology and habitat use patterns of meta-populations. This information is currently lacking for sage-grouse populations that inhabit the Bear Lake Plateau and Valley (BLPV), encompassing parts of Idaho, Utah and Wyoming. I captured, radio-marked and monitored 153 sage-grouse in the BLPV from 2010–2012 to assess nest success, brood survival, mortality factors, and habitat use. Reproductive success was lower than range-wide averages, with especially low success in 2011. Nesting and brood rearing both showed higher success rates in 2012. Survival was very similar to estimates found elsewhere. Females had higher survival rates than males, and yearlings had higher survival probability than adults. Sage-grouse mortality was highest in summer and spring, and lowest in fall. Individual sage-grouse completed large scale movements, often using habitats in Idaho, Utah, and Wyoming. Important factors in sage-grouse habitat selection included distance to major road, distance to habitat edge, distance to vertical structure (i.e., communication towers, wind turbines, and transmission lines), and vegetation cover types. Sage-grouse tended to avoid major road and vertical structures (i.e., communication towers, wind turbines, and transmission lines). They also selected habitat further away from habitat edge. Vegetation types preferred by sage-grouse included shrubland habitats, wet meadows, and grassland. MaxEnt models did not place highest importance on sagebrush habitats, which are critical for sage-grouse presence. This could have occurred because the vegetation layers used in the model did not assess habitat quality. Models produced using the ten landscape variables and BLPV sage-grouse locations ranked good to excellent fits. State-defined habitat covered a larger extent than MaxEnt predicted habitat. MaxEnt predicted habitat areas may be used to further refine state identified core areas to assist in prioritization of conservation efforts to protect the BLPV sage-grouse population.

Indiana University-Purdue University Indianapolis (IUPUI) / The Indian summer monsoon (ISM) is the dominant hydrometeorological phenomenon that provides the majority of precipitation to southern Asia and southeastern Tibet specifically. Reliable projections of ISM rainfall are critical for water management and hinge on our understanding of the drivers of the monsoon system and how these drivers will be impacted by climate change. Because instrumental climate records are limited in space and time, natural climate archives are required to understand how the ISM varied in the past in response to changes in climatic boundary climate conditions. Lake sediments are high-resolution natural paleoclimate archive that are widely distributed across the Tibetan Plateau, making them useful for investigating long-term precipitation trends and their response to climatic boundary conditions. To investigate changes in monsoon intensity during the Holocene, three lakes were sampled along an east-west transect in southeastern Tibet: Galang Co, Nir’Pa Co, and Cuobu. Paleoclimate records from each lake were developed using isotopic (leaf wax hydrogen isotopes; δ2H), sedimentological, and geochemical proxies of precipitation and lake levels. Sediments were sampled at high temporal frequencies, with most proxies resolved at decadal scales, to capture multi-decadal to millennial-scale variability in monsoon intensity and local hydroclimate conditions. The ISM was strongest in the early Holocene as evidenced by leaf-wax n-alkane δ2H at both Cuobu and Galang Co corresponding with Cuobu’s higher lake levels and effective moisture. Monsoon intensity declined at Cuobu and Galang Co around 6 ka which corresponds to reduced riverine sediment influxes at Cuobu and deeper lake levels at Galang Co. The antiphase relationship between lake levels and monsoon intensity at Galang Co is attributed to air temperatures and effective moisture, with a warmer and drier local hydroclimate driving early Holocene low lake levels. The late Holocene ISM was more variable with wet and dry periods, as seen in the Nir’Pa Co lake level and leaf wax n-alkane δ2H record. These records demonstrate coherent drivers of synoptic and local hydroclimate that account for Holocene ISM expression across the southeastern Tibetan Plateau, indicating possible drivers of future monsoon expression under climate change.

No description available.

In the past decade there has been a call for integrated studies that examine the interaction of fluvial and aeolian processes (Belnap et al., 2011; Bullard and Livingstone, 2002). In this study, we examined the role of land-use, weather, and soil type on the flux of aeolian material into dry washes on the Colorado Plateau in central Utah, USA, and western Colorado, USA. Our goal was to quantify the impact of individual deposition and erosion events by correlating weather and land-use data with a combination of measurement methods including dust collection via dust traps, GPS surveying, and close-range photogrammetry. Our data suggest that there is an interaction between these processes and that seasonality and land-use play a large role in determining the strength of this interaction. Particularly, high land-use and dry, windy conditions were most conducive to the surface movement of sediment and subsequent removal of that sediment by fluvial processes.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The ecology of subalpine fir relative to broom rust was investigated. Broom rust infections were most common in trees growing on limestone soils, and seldom occurred on trees growing on basalt soils. Even though plant moisture stress was consistently higher in the plants from limestone soils, the studies indicated that moisture stress is not the major factor causing infection. The amounts of available magnesium and phosphorus were much lower in the limestone soil. It is postulated that the higher plant moisture stress of subalpine fir growing on limestone soils may aggrevate the lack of nutrients and be a contributing factor to the susceptibility of subalpine fir to broom rust. Even though the study raises more questions than it answers, management prescriptions relative to this disease can be proposed. Pruning and burning of diseased branches should be evaluated as a possible method to control broom rust on subalpine fir. This species must be better managed because of its strategic position on watersheds and recreation sites of higher elevations.

No description available.