Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

M.Sc. (Geology) / Please refer to full text to view abstract

The Chemung Formation in the south-central Appalachians constitutes part of the thick Devonian - lower Mississippian Acadian clastic wedge. Sediment in the Chemung was derived from a progressively-uplifted source area to the east and accumulated in the proximal environments of an epeiric sea. Sandstones within the dominantly muddy formation are found in a variety of sequence types characterized by hummocky cross stratification. Individual beds usually have sharp erosive bases and gradational tops. A hydrodynamic interpretation of hummocky sequences suggests that they are the result of extremely large but infrequent storm events and are surrounded by fair-weather deposits of mud rock. The Chemung shelf is envisaged as a very low-gradient (<0.5 ft./mile) clastic ramp extending hundreds of miles toward the craton interior. Transport of sand from the nearshore onto the shelf over distances up to 200 miles was facilitated by storm generated gradient currents. Coarsening/thickening- upward sequences of storm beds represent progradational shelf sand lobes. Three facies associations represent environments of deposition and record changing styles of storm sedimentation on the shelf. The distal inner shelf environment is characterized by discrete hummocky sandstone sequences deposited by only the largest of storms. The proximal inner shelf environment is a much higher energy environment in which periodic storms and fair-weather waves shoal on the low gradient sea floor producing thicker and amalgamated storm sequences. A low-energy shoreline environment is situated landward of the proximal inner shelf and contains only minor storm and fair-weather deposits. The widespread occurrence of hummocky sequences within the Chemung illustrates the importance storm processes can have in the transportation and deposition of sediment in shallow-marine settings. / Master of Science

This research involved the study of sediment cores from Loch Etive, Loch Long, Loch Goil and Loch Fyne with the aims of investigating the geochemistry of natural, and manmade radionuclides and heavy metals within the sea loch environment. The main aims of the research were to determine accumulation rates and the extent of mixing within these sediments and to assess the fluxes, sources and temporal variations in input of pollutant heavy metals to these environments. In recent years it has been suggested that Pb is mobile in sea loch sediments which questions the validity of applying ²¹⁰Pb dating in this environment. This has important implications with respect to interpreting sediment cores to assess temporal trends of pollutant inputs and investigating the rates of physical and biogeochemical processes that are taking place in the coastal environment. Hence, one of the aims of this research was to determine whether Pb was mobile in these sediments. The ²⁰⁶Pb/²⁰⁷Pb isotope ratio can potentially be used to determine the extent of pollutant Pb input from leaded petrol to the environment and a further objective of the work was to investigate the isotopic signature of pollutant Pb in the sediment. Concentration of ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²²⁸Th, ²³⁸U, ¹³⁷Cs, ¹³⁴Cs and ²⁴¹Am in the sediments were analysed using gamm a spectroscopy and the heavy metals, Pb, Zn and Cu were determined using X-ray Fluorescence. Stable Pb isotope ratios were determined using Inductively coupled plasma Mass spectrometry. The results obtained indicated that Pb is not subject to diagenetic mobility in these sediments and that ²¹⁰Pb profiles can be used to determine sedimentation rates for most of the sediment cores. lt was not possible to determine accumulation rates for the two cores from Loch Fyne by ²¹⁰Pb dating, and in this case the sedimentation rate was assessed by correlating the maximum concentration of ¹³⁷Cs in the sediments with the maximum ¹³⁷Cs discharge from Sellafield, BNFL's reprocessing plant located on the Cumbrian coast. The flux of ²¹⁰Pb to the lochs varied significantly suggesting that there has been sediment focusing of fine and/or organic rich material to the deeper sites, resulting in an enhanced flux of ²¹⁰Pb to these sediments. Sellafield waste radionuclides also provided useful chronologies by relating sediment maximum concentrations to maxima in the discharges. ¹³⁷Cs was observed to be subject to diffusive movement, invalidating the use of its total depth of penetration as a chronological indicator. The temporal trends of pollutant metal input agreed well with known historical trends and the Pb isotope profiles indicated that the onset of deposition from pollutant Pb from petrol occurred in the late 1920's. The maximum input of Pb from petrol peaked in the early 1980's and since then there has been a decrease in this input. The two sea lochs which were closest to the industrial centre of Glasgow exhibited a large anthropogenic pollutant input, confirming that these sediments have been highly perturbed by human activities, either directly as a result of sludge dumping or due to changes in land use (eg. road construction, deforestation, etc.) in the catchment. All the sea lochs reflected a change in the supply of material to the sediments over the last eighty years, indicating that increased anthropogenic activity has had an effect on these environments.

No description available.

No description available.

Little attention has previously boon given to the sediments of the Eden estuary, Fife, Scotland. This research was performed in order to identify, delineate and account for the observed sedimentary facies in the superficial sediments of the intertidal zone.

Cenozoic deposits in intermontane basins in the upper Gila River basin have been collectively included in the Gila conglomerate of Gilbert and Ransome. Re-examination of type-section areas shows that the term is unsatisfactory because it includes a substantial proportion of deposits other than conglomerates; it suggests that deposits in separate basins are identical; its use masks sequences of alluvial deposits within individual basins and relationships of deposits between basins; and it oversimplifies a complex Cenozoic history. It is suggested that the term Gila conglomerate be abandoned. The deposits, in the many basins, which heretofore may have been included in the Gila conglomerate, can be separated into two major divisions which may in turn be subdivided into mappable rock units. In each structural trough the upper units are characterized by: (1) Truncation by the highest pediment surfaces; (2) depositional or normal-fault contact with adjacent mountain areas whose composition the deposits reflect; (3) size-gradation relationships that suggest deposition within the boundaries of the present structural troughs; and (4) lack of mineralization. Limited fossil evidence suggests that deposition occurred during Pliocene to Pleistocene (Kansan) time. The lower units crop out in areas of deep dissection or structural uplift. They may be in fault contact with the upper units, underlie them unconformably, or grade into them. The lower units are characterized by: (1) Texture and composition that suggest deposition in basins other than those reflected by the present topography; (2) thrusting or normal faulting more complex than that associated with the upper units; (3) local mineralization; and (4) shallow intrusion. Limited fossil evidence sug gests a Miocene age for some of the older of the lower units, The alluvial deposits in individual basins in this area are amenable to stratigraphic analysis by standard procedures for describing rock units Correlations within or between basins should be on the basis of proper fossil or stratigraphic evidence and should be limited to the particular units involved and not expanded to include all the alluvial deposits in the areas concerned.

The main objective of this study is an assessment of the potential of applying land use optimization methods for minimizing the sediment yield from catchments. The study area is the Siran watershed, a subwatershed of the Tarbela watershed in Pakistan which drains directly into the Tarbela reservoir. It has an area of 4Ub sq. miles and receives 47.82 inches annual average precipitation. The main land use practices on the Siran Watershed are agriculture, rangeland grazing and forestry. A stochastic model for simulating daily precipitation and another for simulating daily maximum temperatures are developed for the area. The synthetic daily precipitation events are transformed into daily streamflows by the soil moisture counting streamflow model using the synthetic daily maximum temperatures as input. The streamtlow model, called the Generalized Streamflow Simulation System, is modified and used for simulating baseflow recessions. The stochastic precipitation model, the stochastic temperature model and the deterministic streamflow models were combined with the deterministic sediment yield model for simulating sediment yield from the watershed. The modified Universal Soil Loss Equation was used for simulating sediment yield. Parameters at these models were determined from data taken on the Siran Watershed. A linear program was used for land use optimization to minimize sediment yield and maximize watershed production. Both optimization processes ended up with the same land use areas allocating the Maximum area for forests. The expected sediment yield was reduced by 2.5 times and production of watershed was doubled. Optimization of crops was accomplished by maximizing the production of agriculture lands. This resulted in the allocation of major agriculture land areas for apple orchards. By adopting the final optimized land use practices, the sediment yield can be reduced to half and watershed production can be increased six times. The results of the present study are encouraging and indicate that application of land use optimization methods for reducing sediment yields nave great potential on the study area and on other subwatersheds of the Tarbela and Manyla Watersheds. The methodology developed in this study can provide a useful tool for watershed managers to reduce sediment yields and increase the income of the local inhabitants by maximizing the agriculture production in other parts of the country.

On average, one percent of reservoir storage capacity is lost annually to sediment deposition in reservoirs. Several methods for sediment removal do exist, but most are inefficient and costly in terms of money or water usage. One method known as siphoning has been shown to adequately remove sediment, but present knowledge is lacking to optimize this method for removal. Three relationships for sediment transport in a pipe were compared against data collected from a physical model resembling a reservoir siphoning system. None of the three accurately predicted the physical model results. However, some trends among the relationships were observed, indicating that with additional modification to the relationships, parameters could possibly be developed to design a prototype system.