Geo-Marine Letters

, Volume 29, Issue 6, pp 359–378

Evolution and preservation potential of fluvial and transgressive deposits on the Louisiana inner shelf: understanding depositional processes to support coastal management

  • James Flocks
  • Michael D. Miner
  • David C. Twichell
  • Dawn L. Lavoie
  • Jack Kindinger
Original

DOI: 10.1007/s00367-009-0164-4

Cite this article as:
Flocks, J., Miner, M.D., Twichell, D.C. et al. Geo-Mar Lett (2009) 29: 359. doi:10.1007/s00367-009-0164-4

Abstract

The barrier-island systems of the Mississippi River Delta plain are currently undergoing some of the highest rates of shoreline retreat in North America (~20 m/year). Effective management of this coastal area requires an understanding of the processes involved in shoreline erosion and measures that can be enacted to reduce loss. The dominant stratigraphy of the delta plain is fluvial mud (silts and clays), delivered in suspension via a series of shallow-water delta lobes that prograded across the shelf throughout the Holocene. Abandonment of a delta lobe through avulsion leads to rapid land subsidence through compaction within the muddy framework. As the deltaic headland subsides below sea level, the marine environment transgresses the bays and wetlands, reworking the available sands into transgressive barrier shorelines. This natural process is further complicated by numerous factors: (1) global sea-level rise; (2) reduced sediment load within the Mississippi River; (3) diversion of the sediment load away from the barrier shorelines to the deep shelf; (4) storm-induced erosion; and (5) human alteration of the littoral process through the construction of hardened shorelines, canals, and other activities. This suite of factors has led to the deterioration of the barrier-island systems that protect interior wetlands and human infrastructure from normal wave activity and periodic storm impact. Interior wetland loss results in an increased tidal prism and inlet cross-sectional areas, and expanding ebb-tidal deltas, which removes sand from the littoral processes through diversion and sequestration. Shoreface erosion of the deltaic headlands does not provide sufficient sand to balance the loss, resulting in thinning and dislocation of the islands. Abatement measures include replenishing lost sediment with similar material, excavated from discrete sandy deposits within the muddy delta plain. These sand bodies were deposited by the same cyclical processes that formed the barrier islands, and understanding these processes is necessary to characterize their location, extent, and resource potential. In this paper we demonstrate the dominant fluvial and marine-transgressive depositional processes that occur on the inner shelf, and identify the preservation and resource potential of fluvio-deltaic deposits for coastal management in Louisiana.

Supplementary material

367_2009_164_MOESM1_ESM.pdf (2.1 mb)
Supplementary material, approximately 2.08 MB.

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • James Flocks
    • 1
  • Michael D. Miner
    • 2
  • David C. Twichell
    • 3
  • Dawn L. Lavoie
    • 4
  • Jack Kindinger
    • 1
  1. 1.Florida Integrated Science CenterU.S. Geological SurveySt. PetersburgUSA
  2. 2.Pontchartrain Institute for Environmental SciencesUniversity of New OrleansNew OrleansUSA
  3. 3.U.S. Geological SurveyWoods HoleUSA
  4. 4.U.S. Geological SurveyStennis Space CenterUSA

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