See more from this Division: Topical Sessions
See more from this Session: Late Quaternary of the Northern Gulf of Mexico Margin: Climate Change, Sea-Level Change, and the Depositional Record
Abstract:
Chenier-Plain development was commonly accepted to have been driven entirely by Mississippi-River autocyclicity as illustrated by Hoyt's (1969) model depicting transgressive cheniers and regressive mudflats. However, Hoyt's model oversimplifies Chenier-Plain evolution because it omits ridges created by non-transgressive processes. Thus, Chenier-Plain evolution is more complex than Mississippi River channel avulsions, and it involved not only chenier ridges (transgressive), but also beach ridges (regressive) and spits (laterally accreted). A six-stage geomorphic process-response model was developed to explain Chenier-Plain evolution as a function of: 1) the balance between sediment supply and energy dissipation associated with Mississippi River channel avulsions, 2) local sediment reworking and lateral transport, 3) tidal-entrance dynamics and sediment trapping, and 4) possibly higher-than-present stands of Holocene sea level. Hence, development of transgressive, regressive, and laterally-accreted ridges typically occurred contemporaneously along the same shoreline at different locations.
Possible geomorphic evidence for higher-than-present stands of Holocene sea level lies in the development of various ridges that have maximum elevations that exceed 2.5 m. Of the eight primary paleoshoreline trends on the Chenier Plain, maximum elevations tend to occur along two prominent ridge trends, the Little Chenier-Little Pecan Island trend and the Grand Chenier trend, which are the two most important paleoshorelines because of their lateral extent and relief.
See more from this Division: Topical Sessions
See more from this Session: Late Quaternary of the Northern Gulf of Mexico Margin: Climate Change, Sea-Level Change, and the Depositional Record