Thesis (M.S.)--Virginia Polytechnic Institute and State University, 2002. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: William E. Galloway. Vita. Includes bibliographical references.

Thesis (M.S.)--Humboldt State University, 2006. / Includes bibliographical references (leaves 85-90). Also available via Humboldt Digital Scholar.

Zugl.: Bochum, Universiẗat, Diss., 1990.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. Title from title screen (viewed Sept. 20, 2007). Includes bibliographical references (leaves 108-114). Online version of the print original.

Thesis (Ph. D.)--College of William and Mary. / Supplemental material for Appendices A-C on CD-ROM.. Includes bibliographical references.

This thesis explores a number of hydrodynamic sedimentation problems in which the fluid motion is governed by the quasi-steady Stokes approximation. In Chapter Two potential-theoretic methods are used to solve the axisymmetric sedimentation problem of a small slowly rotating and translating particle moving through a fluid-filled circular pore of finite length. In such an approach the velocity and pressure fields, governing the fluid motion, are expressed in terms of relevant harmonic functions, a method which is also applicable to linear elasticity. To give the motivation behind the selection of these harmonics and the analytic methods used, Chapter One discusses two electrostatic problems possessing analogous boundary conditions. In both chapters each problem is reduced to the solution of coupled infinite systems of linear equations and solved by truncation to coupled finite sets. The numerical solutions of these equations are then used to compute approximations to the resistive torque and drag experienced by the sedimenting particle. Chapter Three is divided into two parts. Part I treats the application of the method of subareas to some model electrostatic problems. In Part II we utilize the Oseen integral representation of solutions of the Stokes equations to develop a boundary-integral method for the study of further sedimentation problems. The method involves the discretization of the linear integral equations of the first kind, whose unknowns comprise boundary-stress components, using the method of subareas, thus reducing the integral equations to a system of linear equations. Problems solved using this method include the axial translation of a small particle towards a rigid square plate, an investigation of the flow field development for an axially translating small body moving through a hollow and constricted circular cylinder of finite length, the broadside motion of a circular disk through a circular cylinder and an investigation of a curious phenomenon, known as 'overshooting', in the developing axial velocity profile within a finite-length circular cylinder, given certain inlet and outlet velocity profiles.

A dynamic mathematical model has been constructed for the computer simulation of sedimentation in free meandering streams. The system is defined in terms of form and process, and component mathematical models (with mainly deterministic, but also probabilistic, characteristics) are formulated for the prediction of the following aspects of the system for a given physical situation and a single time increment; (l) The characteristics of the plan form of free meanders; (2) The movement of meanders in plan, and definition of cross sections across the meander in which erosion and deposition are considered in detail; (3) The hydraulic properties of the channel and the erosional and depositional activity within the channel as defined in specific cross sections; (4) Whether neck or chute cut off will occur; (5) A relative measure of the discharge during seasonal high water periods, which s is used in (3) and (4); (5) Aggradation. The limitations, qualifications and validity of the component mathematical models are discussed during their development, as is the input required. The overall model has been translated into a FORTRAN IV computer program and a set of experiments with selected input parameters has been performed. The results and their implications are fully documented and compared qualitatively with recent and ancient fluviatile sedimentation. The shape of simulated pointbar sediments, as controlled by channel migration over floodplains of variable sediment type, agrees broadly with the natural situation. Sheet deposits cannot be simulated because large-scale meander-belt movements are not accounted for; this also inhibits generation of thick sequences of alluvial sediments. When channel, migration is combined with a constant aggradation rate the model predicts a general slope (relative to the land surface) of facies boundaries and scoured basal surfaces upward in the direction of channel movement. If aggradation sufficiently increases the thickness of fine grained overbank material, there is a channel stabilisation effect. Epsilon cross-stratification, which represents the shape of a pointbar surface before falling-stage deposition (lateral and vertical), may be picked out in the simulated sediments. The epsilon unit thickness is that measured from bankfull stage down to the lowest channel position existing prior to deposition. The model records the characteristic fining upwards of grain sizes in the pointbar, and the systematic distribution of sedimentary structures. Channel migration combined with seasonal scouring and filling across the channel produces a characteristic relief in the basal scoured surfaces and the grain size and sedimentary structure boundaries. A related lensing and inter- fingering of grain size and sedimentary structure facies may also be present. The model also records large-scale lateral changes in grain size and sedimentary structure associated with changes in the shape of developing meanders. It is shown that a complete sequence of pointbar sediments capped by overbank sediments would rarely be preserved in the moving-phase situation. Such preservation only becomes likely when an aggrading section lies out of range of an eroding channel for a considerably longer time span than it takes a meander to move one half-wavelength downvalley. Deep channel-scours have a higher preservation potential than contemporary shallower ones. Where appropriate field data exist the model can be used in the more accurate recognition of ancient fluviatile sediments. Inferences may be made about the erosion-deposition processes operating in the ancient channel system, and the geometry and hydraulics of the system can be alluded to. A representative application of the model to the quantitative interpretation of an ancient pointbar deposit is illustrated. There is reasonable agreement between the natural and the simulated deposits, and a broad quantitative picture of the palace environment of sedimentation is obtained.

The aim of this research was to examine the depositional architecture of the Northern Mauritanian passive margin, West Africa, in order to infer the geological evolution from Mesozoic to Recent. The study is based on a seismic stratigraphic analysis of 2D and 3D seismic reflection data (18000 km2), well data, outcrops and published work. The results are summarised on fifteen paleogeographic maps and key points in the sedimentary and tectonic evolution of this study can be made. Important subsidence in the southern area occurred from the Jurassic to the Turonian, which caused the development of a fractured flexure zone. This was the main tectonic activity clearly seen in the study area. During the Early Cretaceous, the entire study area was located in a siliciclastic deep-water slope environment. From the Late Cretaceous to the Paleocene, the northern study area became progressively shallower and a carbonate platform developed, while deltas were supplying sediment to the deep-water slope in the southern study area. The Paleocene Thermal Maximum climatic event caused the demise of the carbonate platform in the northern area. From the Middle Eocene to the Recent, most of the area was in a siliciclatic deepwater slope environment. Rivers and deltas that drained the adjacent craton were supplying sediment to the area, which exhibits a complex architecture of gravity and bottom current deposits. Presently, numerous deep-water tributary channels incise the seabed of the study area. This study represents the first reconstruction of the paleoenvironmental evolution of the Mauritanian passive margin from Mesozoic to Recent.

Cone penetration tests (CPTs) have been developed for engineering investigations of sands and finer sediments. CPTs produce high resolution, repeatable and continuous records to depths of several tens of metres, and resemble wireline logs used in the petroleum industry. It is the objective of this dissertation to demonstrate that they can be used for facies analysis in a similar manner, by using these data to develop a facies model for the modern Fraser River delta, British Columbia, Canada. CPT data provide reliable estimates of sediment type and gram size, so that bed thicknesses, sharp and gradational contacts, coarsening and fining upward sequences, bed continuity and dips can be readily identified. The facies model of the Fraser delta is based on a database of over 800 CPTs and 20 continuously cored boreholes. These data demonstrate that the topset is dominated by a nearly continuous sharp-based sand unit that is 8 to 30 m thick, fines upward and is interpreted to represent a complex of distributary channel deposits. The widespread distribution of this sand unit is the result of distributary channel migration in a tidal flat setting and avulsion or channel switching in the upper delta plain. The sand unit is gradationally overlain by a thinner sequence of interbedded sands and silts deposited in tidal flat, abandoned channel and floodplain environments. Deposits of the upper foreset (<60 m) dip up to 7° seaward and are dominated by silts, interbedded and interlaminated with sands. Several intergradational facies, ranging from dominantly silt to dominantly sand, occur and represent increasing proximity to active distributary mouths. These sediments are organized into metre-scale sandy and silty coarsening-upward sequences that are interpreted to represent annual deposits, and sharp-based sand units that represent sedimentary gravity flow deposits. Deeper foreset deposits are dominated by bioturbated silts. The distribution of facies on both the topset and the foreset has been controlled by the interaction of tidal and fluvial processes. CPT data played a key role in developing this facies model of the Fraser River delta. Most facies have distinct CPT signatures. For example, the topset sand unit and overlying deposits have a CPT signature comparable to the “bell-shaped” gamma ray log signature typical of channel deposits. In the foreset, the seaward dips, the coarsening upward sequences and the sharp-based sands are readily observable on CPT data. Although cores were essential to confirm the facies significance of these signatures, the large volume of CPT data permitted recognition of facies distributions and relationships “at a glance” throughout the delta, rather than at the relatively few site where continuous cores were available. Furthermore, CPTs can be acquired for a fraction of the cost of continuous cores, so that CPT data are potentially an invaluable tool for stratigraphic investigations of other modern sedimentary environments dominated by sands and finer sediments. / Graduate