Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 302-310).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

The study is based on the post-Messinian depositional sequences of the Ebro continental margin and Nile submarine cone, on the northwestern and southeastern Mediterranean, respectively.  This study is based mainly on the interpretation of 3D geometries and stratigraphical relationships observed on 3D and 2D seismic reflection data. These siliciclastic systems evolved along the Mediterranean ‘passive’ margins at approximately the same time, thus experiencing the same post-Messinian eustatic history.  However, they have been subject to entirely different local forcing, and present markedly different sedimentation histories. while the seismic profiles of the Pliocene-Pleistocene succession of the Ebro continental margin display a complex pattern of well-developed margin-scale clinoforms, seismic profiles on the Nile cone show a succession characterized by mass-transport deposits and channel-levee systems. Major transformations in the long-term architectural style are recognized in both systems and these are correlative in time at the Plio-Pleistocene boundary, suggesting an externally driven mechanism.  Moreover, sediment budget calculations indicate an increase in the amount of sediments delivered to these basins during the Pleistocene. Their architectural development changed not only in response to the effects of changes in external controls on the sedimentary dynamics and sediment transfer processes as the classic sequence stratigraphic model considers, but also through morphodynamic feedbacks.  Oversteepening of the depositional profile as these systems prograded into the deeper basins led to mass failures of the shelf margin and deficits of mass in certain portions of the system that led to their complete re-organization.  The concepts of slope accommodation, mechanisms of sediment redistribution along the continental margin, and the persistence of significant stratigraphic surfaces, are called into question in these systems.

acase@tulane.edu / Though rivers are inextricably linked in our minds with an intermittently flooded overbank environment, surprisingly little is known about the sedimentary processes that operate there, or how they interact with those of the river. The knowledge gap is acute in deltas, where dense populations often necessitate tightly engineered control over flow patterns, leading to disconnected overbank environments that no longer receive input from the main channel. However, the need to understand sedimentary function in the overbank is also acute in deltas, as rising relative sea levels create an urgent need to manage water and sediment resources. This dissertation is presented as three primary chapters, each of which examines a different aspect of the hydrodynamic and sedimentary connection between a river’s channel and its overbank environment. In Chapter 2, my coauthors and I ask which factors enhance overbank sediment retention, and what retention rates might be considered typical in deltas. We compare the sediments stored in a crevasse splay to those transported by the river and conclude that retention rates approaching 100% might be achievable in settings that are not exposed to coastal processes. Chapter 4 is also concerned with spatial patterns of sedimentation on a delta. In it we use physical experiments to examine the influence that floods play in mobilizing sediments from the channel and storing them in the overbank environment. We find, counterintuitively, that an experiment whose input included floods has a lower proportion of floodplain to channel deposits preserved than an experiment with a constant input. Chapter 3 is focused on water and sediment dynamics in the channel in a region where significant flow is lost to the overbank environment. Here we present measurements from channel networks in the Mississippi River’s Birdsfoot Delta and show that flow loss along the channels is a critical control on channel function that causes channels of disparate sizes to behave similarly. We use our field results to inform a numerical model of channel bed evolution in a region with flow losses, and conclude that the modern flood control system in the Lower Mississippi River may have significantly changed the bed morphology. / 1 / Christopher R. Esposito

Memoria para optar al título de Geógrafo / A partir del análisis geomorfológico se estudia la morfología fan-delta asociada a la desembocadura de los ríos Huinay y Lloncochaigua, en la localidad de Huinay, fiordo Comau, región de Los Lagos. Se analizó el contexto especifico territorial y geográfico del ambiente periglacial inserto en cuencas norpatagonicas, con el propósito de caracterizar la morfología deltaica a través de imágenes y fotografías aéreas de las últimas tres decadas desde 1982, analizando la morfología y los cambios internos en las formas deltaicas de Huinay-Lloncochaigua. Se realizó cartografías geomorfológicas bajo las diferentes condiciones de marea, identificando la dinámica subaérea y subacuática de las formas estudiadas. El trabajo de terreno realizado en enero y junio 2016, permitió definir la naturaleza del fan-delta, debido a la marcada impronta aluvial de los lóbulos deltaicos, el patrón braided característico de flujos con abundante carga sedimentaria y bancos compuestos por gravas de origen fluvial. Los resultados obtenidos revelan los patrones de cambio y tendencia evolutiva de la morfología asociada al litoral cercano, los cuales indican que el fan-delta Huinay actualmente se encuentra en procesos de acumulación, acreción y progradación de material. Se plantea la necesidad de avanzar en la investigación de estas formas, más aún en escenarios de cambio ambiental asociados a la disminución de las precipitaciones y aumento de las temperaturas durante el presente siglo.

No description available.

No description available.

This study maps the facies architecture and geometry of stratigraphic surfaces within the tide-influenced upper Sego Sandstone exposed in the Book Cliffs between Crescent Junction and Thompson Springs, Utah. A bedding diagram was constructed by correlating 32 measured stratigraphic logs across this 8.5 kilometer strike-oblique outcrop to interpret depositional environments and the sequence stratigraphic setting of this tidally-influenced sandstone. Five facies associations are defined: marine shale, lower shoreface, tidally-influenced bedsets, heterolithic tidal bedsets, and tidal flat deposits. Vertical facies trends define two sandy intervals separated by a marine shale, that are interpreted to record episodic progradation of deltaic shorelines. Erosion surfaces at the base of these intervals are interrupted to record tidal scouring of the sea floor during falling stage regression. Sandstone-bodies within these intervals shingle westward recording delta lobes that thinned and became more heterolithic. Although sandstone intervals are interpreted to record progradation, internal cross stratification is dominantly tidal-flood oriented. This is interpreted to record preferential preservation of bedload transported by flood tidal currents onshore, even though net sediment was directed offshore in a suspended ebb-oriented hypopycnal plume and as fluid mud during uncommon river floods. Deposits above high-relief erosion surfaces observed to cut down into the upper Sego Sandstone do not meet the criteria for incised valley fills. These surfaces are interpreted to record tidal current enlargement of distributary channels after abandonment. Such incisions thus do not necessarily record changes in sea level.

This research investigates different scenarios of deltaic deposition, both in shelfbreak and ramp settings. I address four ancient cases with particular characteristics: 1) A shelf-margin case from the Eocene Battfjellet Formation, West Spitsbergen, Norway, in which deltas were able to migrate to the shelf-edge during rising and sea-level highstand conditions despite the low-supply character of the system (low progradation/aggradation rates compared to analogous margins), with consequent sand starvation on the slope and deeper areas of the basin. The delta system was overall wave-dominated, with restricted tide-influence at the mouth of the distributaries and more accentuated tide-influence during the transgressive transit of the deltas; 2) A shelf-margin case from the Pliocene paleo-Orinoco Delta System, Mayaro Formation, SE-Trinidad, in which high rates of sediment supply from the paleo-Orinoco River and exceptionally high subsidence rates due to growth-faulting, produced a spectacular stacking of sandstones on the outer shelf and shelf-edge areas, but with apparently limited sand delivery into deeper waters. The delta system was overall storm-wave dominated, with fluvial-influence in the lower segment of the system and some tide-influence in association with the fluvial-influence; 3) A case from a shallow-water ramp, Campanian Rock Springs Formation (Western Interior Seaway), in which deltas accumulated along relatively straight, north-south oriented shorelines highly impacted by wave-storm processes. Tide-influence was limited to the mouth of the distributaries, and fluvial deposits mostly developed within the coastal-plain areas; and 4) A case from the same ramp setting as (3) but in an outer-ramp site, Campanian Haystack Mountains Formation, in which a lowering in sea-level translated the delta system tens of kilometers eastwards into the basin. As a consequence of a shallower and narrower seaway, southerly-oriented tidal currents were enhanced and subsequently skewed or re-aligned the delta system to the south. The key contributions of this research concern (1) the feasibility of shelf-margin accretion during rising and highstand of sea level, (2) the critical importance of shelf width and sediment supply (and not only sea-level behavior) to bring deltas to the shelfedge, and (3) the possible tendency for tides enhancement in the distal reaches of shallow seaway ramps, caused by narrowing of the seaway and fault-topography enhancement during falling sea level. / text

Thesis (Ph. D.)--University of Southern California, 1997. / Includes bibliographical references (leaves 219-229).