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You searched for subject:(hummocky cross stratification). Showing records 1 – 2 of 2 total matches.

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University of Texas – Austin

1. -6179-5957. Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves.

Degree: PhD, Geological sciences, 2019, University of Texas – Austin

Hummocky cross-stratification (HCS) is widely interpreted in wave-influenced ancient shallow-marine deposits. Currently, debate is abundant surrounding HCS with differences in opinions driven partly by poor understanding of the nature and magnitude of processes that lead to HCS formation; lack of enough data to characterize HCS three-dimensional architecture, lateral variability and facies; and inadequate knowledge of how the presence of waves influences sediment movement on marine shelves. This dissertation focusses on filling these knowledge gaps by conducting a tripartite study involving numerical analysis of outcrop exposures of HCS-bearing shelf sands, geostatistical analysis of post-storm-generated bedforms on a modern shelf, and physical modeling of wave interaction with turbid hyperpycnal flows. Numerical analysis and estimated wave time periods from HCS measurements in Late Cretaceous marine transgressive strata in southeastern San Juan Basin, New Mexico, and in deposits of the Cape Sebastian Sandstone (CSS) in southwestern Oregon suggest that HCS in these deposits was more likely formed by decayed swell waves that had travelled long distances away from powerful storms, rather than by active storm waves. These studies suggest that the maximum sustainable wind speeds during greenhouse periods such as those that characterize the late Cretaceous could have been higher than those of modern storms. Study of modern storm deposits shows that sand ridge hydrodynamics affects grain-size variation across the large-scale bedforms (sand ridges and sorted bedforms), which in turn governs the variation in surficial bedforms (megadunes, hummocky bedforms, and 2.5 dimensional dunes). Results indicate that while large-scale bedforms are more current-driven, the small-scale bedforms are more likely to have formed under wave-dominated conditions. These results underscore the role of seafloor morphology on distribution of hummocky bedforms and associated structures on the marine shelf. Lastly, study of wave interaction with turbid hyperpycnal shelf flows shows that wave-generated turbulence helps maintain elevated density in the flows and hence maintains the driving forces of current movement. These elements enable the flow to sustain its energy despite low shelf gradients. These results highlight the contribution of waves in sediment transport across the shelf. Overall, this doctoral dissertation enhances our ability to predict paleo-conditions responsible for deposition of HCS in the geological record, improves our understanding of the role of waves in sand movement on and across shelves, and is the first research to document the relationship between hummocky bedforms and storm processes in the modern shelf. Advisors/Committee Members: Goff, John A. (advisor), Wood, Lesli J. (advisor), Steel, Ronald J (committee member), Mohrig, David (committee member), Kim, Wonsuck (committee member), Southard, John (committee member).

Subjects/Keywords: Hummocky cross-stratification; Shelf sands; Storm processes; Wave-influenced deposits; Multi-beam bathymetry; Hyperpycnal flows

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

-6179-5957. (2019). Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/1998

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Chicago Manual of Style (16th Edition):

-6179-5957. “Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed April 19, 2021. http://dx.doi.org/10.26153/tsw/1998.

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Author name may be incomplete

MLA Handbook (7th Edition):

-6179-5957. “Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves.” 2019. Web. 19 Apr 2021.

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Author name may be incomplete

Vancouver:

-6179-5957. Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Apr 19]. Available from: http://dx.doi.org/10.26153/tsw/1998.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-6179-5957. Influence of surface gravity waves on sediment transport and deposition of hummocky cross-stratified sands on marine shelves. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/1998

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete


Texas A&M University

2. Lyon, Trey Saxon. Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop.

Degree: MS, Geology, 2015, Texas A&M University

The Eagle Ford Formation is currently the most economically significant unconventional resource play in the state of Texas. There has been much debate as to the environment of deposition for the lowermost Facies A of the Eagle Ford in outcrop exposures in Lozier Canyon, Texas. Two conflicting hypotheses were proposed: 1) Sedimentary structures in Facies A are hummocky cross-stratification (HCS) and swaley cross-stratification (SCS), which indicates a shelfal depositional environment above the storm wave base (SWB). 2) Sedimentary structures in Facies A are a mixture of diagenetically separated contourites, turbidites, and pinch-and-swell beds, which indicate a distal-slope depositional environment below SWB. This research used field work, three-dimensional analysis of sedimentary structures, measurements of ripple height, and laboratory analysis to interpret the environment of deposition. The results of these observations and data suggest that the sedimentary structures in Facies A record a depositional environment above SWB. Observation of cross-bedded structures in three-dimensions reveals (i) isotropic truncation of laminae; (ii) symmetric rounded ripples; (iii) large variations in laminae geometry, truncation, and dip inclination, attributed to fluctuations in storm intensity, frequency, and duration; and (iv) and bidirectional downlap and reactivation surfaces associated with oscillatory flow above the SWB. This study interprets cross-bedded sedimentary structures in Facies A as swaley cross-stratification (SCS) and hummocky cross-stratification (HCS) associated with storm events, and thus places Facies A in a depositional environment above storm wave-base (SWB). Advisors/Committee Members: Giardino, John R (advisor), Laya, Juan Carlos (committee member), Pope, Mike (committee member), Houser, Christopher (committee member).

Subjects/Keywords: Eagle Ford; Boquillas; sedimentology; hummocky cross stratification; tempestite; depositional environment; outcrop; Lozier Canyon; Osman Canyon; cross bedding; cross; HCS; swaley; turbidite; contourite; West Texas

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lyon, T. S. (2015). Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155182

Chicago Manual of Style (16th Edition):

Lyon, Trey Saxon. “Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop.” 2015. Masters Thesis, Texas A&M University. Accessed April 19, 2021. http://hdl.handle.net/1969.1/155182.

MLA Handbook (7th Edition):

Lyon, Trey Saxon. “Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop.” 2015. Web. 19 Apr 2021.

Vancouver:

Lyon TS. Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop. [Internet] [Masters thesis]. Texas A&M University; 2015. [cited 2021 Apr 19]. Available from: http://hdl.handle.net/1969.1/155182.

Council of Science Editors:

Lyon TS. Determining the Depositional Environment of the Lower Eagle Ford Group in Lozier Canyon, Antonio Creek, and Osman Canyon: An Out Crop Study of Bedding Features a Study of Bedding Features at Outcrop Scale or in the Outcrop. [Masters Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155182

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