Browsing by Subject "Lake deposition"

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Deep lacustrine clinoforms : formation, architectures, and deposits
(2016-08-16) Fong-Ngern, Rattanaporn; Steel, R. J.; Olariu, C. (Cornel); Mohrig, David C.; Kim, Wonsuck; Krézsek, Csaba
This dissertation is a study of the occurrence, geometry, stratigraphy and sedimentological characteristics of shelf-margin clinoforms in a deep lake setting. Because of their formation in a hydrologically closed environment, and reduced salinity water, lake clinoforms’ characteristics can differ from their well-studied marine counterparts. An investigation on lake clinoforms can lead to a better understanding of lake depositional processes, particularly those that provide a linkage between the co-genetic shallow-deepwater depositional environments, and consequent sediment dispersals in a deep lake setting. Even though similar processes also operate in a deep-marine setting, their interaction within the reduced salinity water of a lake can build deposits and stratigraphy that differ from marine basin fill. Hence, this study provides a good example of lake clinoforms and their deposits, which can be used for comparison with those of marine environment. For the most part, this study is performed on the western Dacian Basin datasets, which comprise subsurface and outcrop data. The subsurface dataset includes three overlapping 3D seismic volumes that cover 1,700 square-kilometer area and well data. The entire basin fill succession is exposed and allows up to 1000 m thick sedimentological data to be collected. The seismic data analysis suggests that a closed nature and isolation from the effects of eustatic sea-level changes contributed to limited aggradation of the Dacian clinoform topsets and significant sediment partition to the deep-lacustrine environments, which led to rapid foreset progradation and high bottomset aggradation. Integration between the subsurface and outcrop datasets shows that direct sediment transport from the shelf to the basin-floor environments is common and carried through hyperpycnal-flow channels and mass-wasting of the shelf edge. Based on the Dacian Basin clinoforms’ distinctive bottomset geometry, a special attention was given to the base-of-slope as a crucial point to scrutinize basin-floor sedimentation and sediment partitioning between the deepwater slope and basin floor settings. From the Dacian Basin seismic dataset, a base-of-slope trajectory analytical concept is developed and proposed as a complimentary predictive tool to the shelf-edge trajectory concept. The base-of-slope trajectory analysis was also applied to other published clinoform data to test its applicability