Letter abstract
Nature Geoscience 1, 173 - 176 (2008)
Published online: 17 February 2008 | doi:10.1038/ngeo129
Subject Category: Geomorphology
Mississippi Delta subsidence primarily caused by compaction of Holocene strata
Torbjörn E. Törnqvist1, Davin J. Wallace1,3, Joep E. A. Storms2,4, Jakob Wallinga2,5, Remke L. van Dam2,6, Martijn Blaauw2,7, Mayke S. Derksen2,8, Cornelis J. W. Klerks2,9, Camiel Meijneken2,10 & Els M. A. Snijders2,11
Coastal subsidence causes sea-level rise, shoreline erosion and wetland loss, which poses a threat to coastal populations1. This is especially evident in the Mississippi Delta in the southern United States, which was devastated by Hurricane Katrina in 2005. The loss of protective wetlands is considered a critical factor in the extensive flood damage. The causes of subsidence in coastal Louisiana, attributed to factors as diverse as shallow compaction and deep crustal processes, remain controversial2, 3, 4, 5, 6, 7, 8, 9, 10, 11. Current estimates of subsidence rates vary by several orders of magnitude3, 6. Here, we use a series of radiocarbon-dated sediment cores from the Mississippi Delta to analyse late Holocene deposits and assess compaction rates. We find that millennial-scale compaction rates primarily associated with peat can reach 5 mm per year, values that exceed recent model predictions5, 9. Locally and on timescales of decades to centuries, rates are likely to be 10 mm or more per year. We conclude that compaction of Holocene strata contributes significantly to the exceptionally high rates of relative sea-level rise and coastal wetland loss in the Mississippi Delta, and is likely to cause subsidence in other organic-rich and often densely populated coastal plains.
- Department of Earth and Environmental Sciences, Tulane University, 6823 St. Charles Avenue, New Orleans, Louisiana 70118-5698, USA
- Department of Physical Geography, Utrecht University, PO Box 80115, NL-3508 TC Utrecht, The Netherlands
- Present address: Department of Earth Science, Rice University, Houston, Texas 77251, USA
- Present address: Department of Geotechnology, Delft University of Technology, NL-2600 GA Delft, The Netherlands
- Present address: Netherlands Centre for Luminescence Dating, Delft University of Technology, NL-2629 JB Delft, The Netherlands
- Present address: Department of Geological Sciences, Michigan State University, East Lansing, Michigan 48824, USA
- Present address: Shell International Exploration and Production, NL-2280 AB Rijswijk, The Netherlands
- Present address: Government Service for Land and Water Management, NL-2500 CG The Hague, The Netherlands
- Present address: Vestigia Ltd Archaeology and Cultural History, NL-3813 AA Amersfoort, The Netherlands
- Present address: ProRail, NL-3500 GA Utrecht, The Netherlands
- Present address: Ministry of Housing, Spatial Planning and the Environment, NL-2500 GX The Hague, The Netherlands
Correspondence to: Torbjörn E. Törnqvist1 e-mail: tor@tulane.edu
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