No description available.

Site index curves were constructed for the Emory oak (Ouercus emoryi) woodlands of the San Rafael Valley in southeastern Arizona. The woodlands primarily consisted of trees that were of sprout origin. Growth was rapid for 10 years, moderate from 10 to 20 years, and slow after 20 years. No trees in the study area were more than 40 feet tall. Stepwise regression analysis was used to analyze the relationship between site index and site factors. Important variables included available soil water holding capacity, percent volume of coarse fragments, radiation index, percent sand, litter depth, and soil pH. Two models were developed; the r² values were 0.56 and 0.49, respectively. Analysis of variance was used to test for differences between site index on different soil types and slope positions. All statistical tests were conducted using a 0.10 level of significance. The sample consisted of 100 trees. Most of the factors were involved with availability of water to the tree roots. Emory oak grows in a dryland area where water is a limiting factor. Therefore, the effect that soil and terrain has on the availability of water to tree roots is an important impact on the site index for Emory oak woodlands.

No description available.

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2007. / Includes bibliographical references (p. 41-44).

We examined small-displacement faults in the Jurassic Entrada Sandstone adjacent to the Iron Wash Fault, central Utah east of the San Rafael Swell, in order to describe the nature and timing of past fluid movement and deformation in the Entrada Sandstone. Using field studies, microscopy, and X-ray diffraction analysis, we identified mineralized fractures and cementation features in association with deformation bands and fractures at the interface of the Earthy and Slick Rock Members of the Entrada Sandstone. Where the faults cross the Earthy-Slick Rock Member interface, deformation band faults in the Slick Rock Member become opening-mode fractures in the Earthy Member. These fractures are frequently mineralized with calcite, and goethite pseudomorphs after pyrite, providing evidence of at least two phases of fluid flow from the Entrada reservoir into the caprock in connection with deformation bands. We also observe mineralized fractures, poikilotopic cementation, and spherical to elongate concretions on and within deformation band fins in the Slick Rock Member. These features indicate the presence and movement of fluids parallel to and between deformation band fins. At some sites, deformation band faults and fractures cross and offset the interface; at others, they are present in both units, but deformation band faults do not cross the interface and fractures are not directly connected to any bands. Mineralized fractures are only found at breached-interface sites; evidence for fluid flow in the Slick Rock Member is only found in deformation band fins. Interface crossing and fracture formation is not related to proximity to the Iron Wash Fault. We propose that mesoscale faults can act as seal bypass systems and allow fluid leakage from reservoir rock into overlying less permeable rocks. Deformation bands act as both conduits for and barriers to flow, seen most clearly in deformation band fins where iron staining and mineralization is constrained between sets of bands within the fin. In CO2 or wastewater injection scenarios, interface deformation may prevent successful fluid trapping and cause re-emission of injected fluids.

Suspended-load rivers are subject to rapid geomorphic changes. In particular during the Holocene Epoch, arroyos of the Colorado Plateau experienced several periods of rapid erosion and aggradation. The most recent period of entrenchment occurred around the turn of the 20th century. The mechanisms responsible for the modern period of aggradation that has followed the most recent period of entrenchment have not been well documented. The research presented in this thesis reveals the mechanisms responsible for modern alluviation of the San Rafael River, which drains the Colorado Plateau The lower 87 km of the San Rafael River, which enters the Green River south of the town of Green River, UT has experienced rapid geomorphic changes during the last 100 years. To quantify these changes, we used a complement of temporally precise and spatially robust methods. By understanding the rates, magnitudes and types of geomorphic changes, we could then identify the mechanisms of these channel changes. The San Rafael River narrowed by 83% between 1938 and 2009 and the floodplain aggraded 1.0 to 2.5 m. Channel narrowing was caused by a reduction in the transport capacity of the river, and was accelerated by the establishment of vegetation, including the non-native tamarisk shrub, on active channel surfaces and the floodplain. Significant water withdrawals during the 20th century have primarily been responsible for the reduction in transport capacity by decreasing the magnitude and duration of the annual snowmelt flood. During this time period, monsoon floods continued to deliver large quantities of fine sediment to the channel. During the 20th century, the channel bed incised in one segment and aggraded in five segments. The two periods of incision that we documented were related to human modifications of the channel and floodplain. With the knowledge of the physical processes that have been responsible for the channel changes in the San Rafael River, prediction of future channel conditions can then be made. The changes to the physical template of the San Rafael River have implications for the management of three endemic fish – the roundtail chub (Gila robusta robusta), the bluehead sucker (Catostomus discobolus), and the flannelmouth sucker (Catostomus latipinnis) – which currently utilize the study area.

Paleoecology of the lowermost Carmel Formation, San Rafael Swell, Emery County, Utah, was studied at nine localmes 2 to 21 miles apart. Eight of the sections contain fossiliferous calcilutites and oolmc limestones in the basal 35 to 135 feet measured. Thickness of the fossiliferous beds ranges up to 10 feet. Beds of barren calcilutites, calcarenites, oolmc limestones, intraclastic limestones, calcareous sandstones, and bedded gypsum, separate the fossiliferous beds. A parallel-bedded, basal quartz sandstone, 0.5 to 7 feet thick, everywhere overlies the Navajo Formation. Molluscs dominate faunal assemblages. Shells are recrystallised to calcite, but external sculpture is preserved in sufficient detail for identification. Lamellibranchs are represented by disarticulated shells in unbroken condmon, oriented convex up. Fossil assemblages constitute four main types: (1) Two widespread and heterogeneous assemblages dominated by Camptonectes sp.; (2) A restricted assemblage consisting only of Trigonia Spa in the northern Swell; and (3) A restricted assemblage consisting only of Ophiomorpha burrows in the southern Swell. Associated with Camptonectes Spa are the lamellibranchs Vaugonia sp., Pronoella sp., Trigonia sp., Lima sp., (?)Ostraes sp., (?)Gryphaea sp., and Isognomon sp.; the gastropods Cossmanea Spa and Nerinea sp., and the crinoid Pentacrinus sp .. Fossil assemblages show an imbalance; Herbivores and sediment feeders are absent, and carnivores (predators) and scavengers (selective detritus feeders) are rare. Disarticulation without great breakage suggests gradual deposmon of shells and carbonate material under moderate energy condmons. On the basis of closest living relatives, the assemblages found in carbonate rocks indicate a wide tolerance of these animals to fluctuations in salinity and temperature. The well developed byssal notch of some pectinids suggests abundant vascular plant live. Abundantly fossiliferous beds are separated by barren beds with some evaporites, a sequence suggesting a warm sea of varying but high salinity. Grain-size ranges and limestone predominance indicate, respectively, differing lateral energy levels, and a low terrigeneous clastic influx.

The highly endemic native fish fauna has experienced dramatic reductions in abundance and range because of anthropogenic activity. In addition to a highly altered flow, temperature, and physical habitat template, many non-native fish species have established populations throughout the basin. The San Rafael River, a tributary of the Green River in southeastern Utah, is home to populations of flannelmouth sucker (Catostomus latipinnis), bluehead sucker (C. discobolus), and roundtail chub (Gila robusta), and has experienced degradations representative of many rivers throughout the Colorado River Basin. Using the San Rafael River as a template, I examined (1) the effect of the non-native fishes on the food web structure of a Colorado River tributary and (2) whether any changes to the food web structure by non-native fishes impact fitness-related vital rates of native fishes in the river. Stable isotope analysis revealed that the non-native fishes present novel predator archetypes to the “three species,” but size-at-age and body condition analyses did not reveal any reduction in fitness between native fishes captured in the presence of the non-native fishes. Additionally, I used site-specific biotic and abiotic measurements to develop a model predicting “three species” relative abundance. Non-native fish abundance and spatially auto-correlated measures of physical habitat were found to be particularly important predictors of “three species” relative abundance. The model was used in combination with a longitudinal habitat survey to predict the current continuous distribution along the length of the lower San Rafael River, as well as to simulate population-level effects of relevant restoration actions. The eradication of non-native fishes resulted in significant population increases for each of the ‘three species,’ and physical habitat restoration resulted in significant population increases when executed in certain reaches, but significant population reductions if executed in other reaches. These results suggest that the restoration of physical habitat without addressing populations of non-native fishes will likely result in a limited response by the “three species,” and that the choice of restoration location is critical to its success.

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2007. / Includes bibliographical references (p. 86-88).

Sequestration of carbon dioxide (CO2) into subsurface porous sandstone is proposed as a method for reducing accumulation of anthropogenic emissions of CO2 into the atmosphere. Natural exposures of reservoir and top-seal pairs in central and southeastern Utah are identified as analogs to proposed CO2 injection targets. Reservoir and top-seal pairs in natural analog exposures are analyzed in tandem to evaluate evidence for paleo-migration of fluids and/or hydrocarbons from the reservoir through the top seal. The San Rafael Swell and Monument Uplift exhibit similar structure and exposures of Jurassic units yet differ in amount and type of host rock alteration due to variable amounts and types of fluids and/or hydrocarbons that migrated along faults and fractures. Macroscopic scale analysis of each monocline included processing of satellite imagery, and creation of depth contour maps. At the mesoscopic scale, fracture spacing acquired from scanline station measurements identified increased fracture frequency in proximity to major fault zones. At the microscopic scale, percentage of degradation and type of mineralization in pore space were used to verify increased fluid flow in proximity to major fault zones. Faults with possible intersections with multiple antithetic faults at depth have an increased probability of allowing for upward migration of fluids and/or hydrocarbons along the fault plane and damage zone, effectively bypassing the top sealing formations. Fault leakage potential maps identified areas where seal bypass along major faults would likely occur during sequestration of CO2. The method was validated by identifying potential migration pathways for oil seeps on the Little Grand Wash fault in central Utah. The San Rafael Swell was geometrically modeled through restoration of eroded formation tops along the fold axis to quantify the interaction between an outward migrating CO2 plume and varying degrees of faulting and fracturing. Analysis of the migration of a CO2 plume front through time exhibits an increasing probability of the outward migrating plume intersecting a leaking feature, with the highest probability of the advancing plume intersecting a potentially leaking feature achieved when faults with 1+ km trace length and mean fracture spacing of 17 cm are taken into consideration. (177 pages)