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Shelf sandstones and hummocky cross-stratification: New insights on a stormy debate

1991; Geological Society of America; Volume: 19; Issue: 6 Linguagem: Inglês

10.1130/0091-7613(1991)019 2.3.co;2

1943-2682

William L. Duke, R. W. C. Arnott, R. J. Cheel,

Methane Hydrates and Related Phenomena

Research Article| June 01, 1991 Shelf sandstones and hummocky cross-stratification: New insights on a stormy debate William L. Duke; William L. Duke 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 Search for other works by this author on: GSW Google Scholar R.W.C. Arnott; R.W.C. Arnott 2ESSO Resources Canada Ltd., 237 4th Avenue S.W., Calgary, Alberta T2P 0H6, Canada Search for other works by this author on: GSW Google Scholar Richard J. Cheel Richard J. Cheel 3Department of Geological Sciences, Brock University, St. Catharines, Ontario L2S 3A1, Canada Search for other works by this author on: GSW Google Scholar Geology (1991) 19 (6): 625–628. https://doi.org/10.1130/0091-7613(1991)019 2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation William L. Duke, R.W.C. Arnott, Richard J. Cheel; Shelf sandstones and hummocky cross-stratification: New insights on a stormy debate. Geology 1991;; 19 (6): 625–628. doi: https://doi.org/10.1130/0091-7613(1991)019 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A new depositional model for hummocky cross-stratified sandstones is based on the following observations. (1) Storms transport coastal sand to the inner shelf under oscillatory-dominant combined flows exerting peak instantaneous bed shear stresses roughly normal to shore. (2) Isotropic hummocky cross-stratification is formed experimentally by large, three-dimensional, symmetrical bed forms generated by long-period, purely oscillatory flow and very strongly oscillatory-dominant combined flow. Anisotropic hummocky cross-stratification is formed by strongly oscillatory-dominant flow. (3) Grain fabric in hummocky sandstones indicates rapid reversals of bed shear stress consistent with deposition under a shore-normal oscillatory flow, initially superimposed on a relatively weak bottom current with a seaward-directed component of motion. Thus, shore-normal transport of coarse bedload on the inner shelf during storms (inferred from studies of ancient units) is caused by the interaction of high-speed oscillatory bottom motions under long-period shoaling waves and a relatively slow shore-oblique bottom current driven by geostrophically balanced coastal downwelling. Turbidity currents are not required to form shore-normal paleoflow indicators from hummocky beds. Large three-dimensional wave ripples generated by waning-storm or swell waves are responsible for much of the hummocky cross-stratification in the stratigraphic record. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.