Tidally Modulated Storm Sedimentation on Open-Coast Tidal Flats, Southwestern Coast of Korea: Distinguishing Tidal-Flat from Shoreface Storm Deposits
Byongcheon Yang, Robert W. Dalrymple, Seungsoo Chun, Michael F. Johnson, Heejun Lee, 2008. "Tidally Modulated Storm Sedimentation on Open-Coast Tidal Flats, Southwestern Coast of Korea: Distinguishing Tidal-Flat from Shoreface Storm Deposits", Recent Advances in Models of Siliciclastic Shallow-Marine Stratigraphy, Gray J. Hampson, Ronald J. Steel, Peter M. Burgess, Robert W. Dalrymple
Download citation file:
Observations of physical processes on the open-coast tidal flats along the southwestern coast of Korea show that tidal modulation of wave energy, as a result of changing water depth, produces composite storm beds that should be distinct from the classic storm beds that characterize wave-dominated shorefaces and shelves with small tides.
Storms (typhoons) during the low-energy summer generate muddy storm beds that superficially resemble the upward-thinning tidal rhythmites that form between spring and neap tides. Sandy, winter storm beds contain both falling-tide deposits that consist of decreasing-energy facies successions and rising-tide deposits that consist of increasing-energy facies successions. Over most of the tidal flat, bioturbation levels are low, even in the summer mud deposits, because of episodic high-energy conditions and high rates of sedimentation. Bimodal levels of bioturbation (negligible in the thin intra-storm, low-tide mud drapes versus more intense in inter-storm, fair-weather deposits) should characterize deposits formed on open-coast tidal flats. The style of bioturbation on the lower flat is similar to that reported from upper shorefaces, whereas the inner flat contains a mixed Skolithos-Cruziana assemblage that is much less diverse than that found in shelf deposits. These observations show that a spectrum of storm-bed types is to be expected between wave-dominated (i.e., shoreface and shelf) and tide-dominated (i.e., tidal-flat) settings.
Figures & Tables
Siliciclastic shallow-marine deposits record the interface between land and sea, and its response to a variety of forcing mechanisms: physical process regime, the internal dynamics of coastal and shelfal depositional systems, relative sea level, sediment flux, tectonic setting, and climate. These deposits have long been the subject of conceptual stratigraphic models that seek to explain the interplay between these various forcing mechanisms, and their preservation in the stratigraphic record. This volume arose from an SEPM research conference on shoreline–shelf stratigraphy that was held in Grand Junction, Colorado, on August 24–28, 2004. The aim of the resulting volume is to highlight the development over the last 15 years of the stratigraphic concepts and models that are used to interpret siliciclastic marginal-marine, shallow-marine, and shelf deposits.