Published ETD Collection
Permanent URI for this collectionhttps://hdl.handle.net/10657/2
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Browsing Published ETD Collection by Author "Abdulah, Kenneth"
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Item Heterogeneity, paleohydrology, and 3D facies architecture of ancient point bars, Ferron Sandstone, Notom Delta, South-central Utah(2013-08) Wu, Chenliang 1987-; Bhattacharya, Janok P.; Khan, Shuhab D.; Abdulah, KennethThis study examined ancient exhumed channel belts from the Cretaceous Ferron Sandstone, Notom Delta in south-central Utah. Extensive plan view exposures with local vertical cliff exposures allowed documentation of channel belt dimension, migration pattern (translation versus expansion) and facies architectures. The cliff exposures allow documentation of channel fill thickness and bedding structure that were used in paleogeographic and paleohydraulic reconstructions. Paleocurrent measurements are consistent within one depositional unit (such as a unit bar or channel belt) and can be used to infer channel flow and bar migration patterns. Four hundred and eight paleocurrent directions were integrated with grain-size measurements to reconstruct the 3D facies architecture of the ancient channel belts. Based on the presence of distinct types of inclined strata of large scale foresets and the channel sinuosity (1.01-1.44.) measured from the paleographic map, the formative river of the point bar complex was interpreted to be a low sinuosity river. The point bar complex consists of four successive component point bars and shows a migration pattern that changes from expansion to translation with increasing sinuosity. By using empirical equations, average channel depth and channel width were determined to be 1.7m-3.6m and 23m-89m respectively. Channel width (around 50m) as measured from abandoned channel lags falls into this range. The large variation of channel belt width may be a result of increasing channel dimension due to increasing sinuosity. Therefore, empirical equations for calculating paleohydraulic parameters are generally applicable but need further refinement for specific river types. Bar thickness measured from vertical outcrops range from 5.4m to 6.3m which gives a much narrower range of 47 to 59 m for the channel width estimation. The discharge of the formative river is estimated to be 115 m3/sec to 387 m3/sec. Grain-size variation shows a distinct coarsening trend from inner bar to outer bar at both the scale of individual point bars and the meander loop complex. Because of the absence of extensive shale drapes between each point bar, petrophysical heterogeneity introduced by grain-size variation of sand and directional permeability anisotropy introduced by different types of cross bedding will be the main type of heterogeneity. The grain-size distribution shows a more complicated pattern compared to previous models and the resulting fluid flow pattern is expected to be more complex as well. Finally, the major controls on the formation of low sinuosity river are gradient, sediment supply, and bank erosion, although high frequency climate changes are interpreted to be responsible for the filling of the whole incised valley system. The fluvial style is a bed-load to mixed-load, high net-to-gross river system with limited suspended content in the flow.Item Quaternary Depositional History of a Shelf-Margin Minibasin, Northern Gulf of Mexico(2015-05) Conklin, Tucker 1989-; Wellner, Julia S.; Sager, William W.; Emmet, Peter A.; Abdulah, KennethHigh-resolution 3D seismic data were used to study the evolution of a shelf- margin minibasin located approximately 160 km off of the coast of Louisiana. Depositional packages were delineated and classified based on observed changes in internal characteristics and lapout patterns. Reconstruction of the depositional history of the minibasin reveals information relating to how depositional styles and architecture change over time in response to eustasy, sediment supply, and salt tectonics. Four shelf-margin deltas were identified and classified into two categories: unstable fluvial-dominated deltas, and stable wave-dominated deltas. Slope failure driven by continued uplift of two salt diapirs bounding the study area on both the eastern and western flanks caused numerous mass-transport complexes to redeposit sediment throughout the minibasin. Slope channels contained within the deltaic packages erode into the underlying substrate, and functioned as a shelf to slope sediment bypass mechanism. Deltaic packages are sometimes capped by muddy transgressive wedges. Prodelta muds and hemipelagic drape deposits also fill portions of the minibasin. A sequence stratigraphic framework was used in order to relate the sediment packages to the sea-level record. Deltaic deposition occurred during lowstand periods, and accounts for the largest packages present in the minibasin. Muddy wedges were sometimes deposited during major transgressions, with high amplitude continuous sediment deposits forming during highstands. Fluvial-dominated deltas show signs of a higher sediment supply and rate, which is indicated by syndepositional internal deformation and greater sediment thicknesses. The wave-dominated deltas present are stable, with no observed deformation. The constraining effects of the minibasin in relation to the depositional styles of the deposits were also examined. In this regard when compared to their open shelf-edge counterparts, the deltas present were more likely to develop shelf to slope bypass systems in the form of slope channel complexes, regardless of wave or fluvial influence.