Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change

Abstract

Research Article| November 01, 2001 Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change Whitney J. Autin; Whitney J. Autin 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Search for other works by this author on: GSW Google Scholar Andres Aslan Andres Aslan 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Whitney J. Autin 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Andres Aslan 1Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, New York 14420, USA Publisher: Geological Society of America Received: 22 May 2000 Revision Received: 31 Jan 2001 Accepted: 27 Apr 2001 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2001) 113 (11): 1456–1466. https://doi.org/10.1130/0016-7606(2001)113<1456:APIPAH>2.0.CO;2 Article history Received: 22 May 2000 Revision Received: 31 Jan 2001 Accepted: 27 Apr 2001 First Online: 01 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 Whitney J. Autin, Andres Aslan; Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change. GSA Bulletin 2001;; 113 (11): 1456–1466. doi: https://doi.org/10.1130/0016-7606(2001)113<1456:APIPAH>2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract Comparison of Pleistocene and Holocene soils developed in Mississippi River meander-belt deposits in Louisiana illustrates the influence of relative sea-level change on pedogenesis. Holocene and Pleistocene meander belts have similar landscape morphologies, lithofacies, and soil characteristics, and probably formed under similar hydrologic regimes. The Pleistocene Avoyelles Prairie meander belt is now terraced, but it was originally graded to a lower relative sea-level position than the Holocene flood plain. Holocene alluvial soils are generally weakly expressed cumulative profiles with abundant redoximorphic features, and formed on an aggrading flood plain with a shallow fluctuating water table. The soil morphology varies with respect to landscape position and overbank lithofacies.Pleistocene alluvial paleosols show evidence for two stages of pedogenesis. During the first stage of pedogenesis, water-table fluctuations and flood-plain aggradation produced profiles with color mottles, iron and carbonate nodules, and weak B and C horizons, similar to Holocene flood-plain soils. The second stage of pedogenesis occurred after the Avoyelles Prairie was terraced and the regional water table fell a minimum of 30 m. Improved soil drainage created oxidizing and acidic conditions, removed free carbonates, dehydrated iron oxides, and transformed clay minerals. This stage produced Pleistocene profiles with brighter matrix and mottle hues, lower pH values, larger and harder iron nodules, and greater kaolinite contents than comparable Holocene flood-plain soils.The primary influence on regional water- table lowering in the southern Lower Mississippi Valley was relative sea-level fall. Mississippi River flood-plain lowering adjacent to the Avoyelles Prairie most likely occurred between the end of oxygen isotope stage 3 and the maximum period of valley entrenchment, during oxygen isotope stage 2. Water-table fall affected pedogenic processes a minimum of 400 km upvalley of the continental shelf margin. Pleistocene Mississippi River paleosols represent excellent analogs for interpreting ancient alluvial paleosols formed during episodes of base-level fall and valley incision. As fluvial entrenchment terraced the meandering Avoyelles Prairie, a pedogenic threshold was crossed that altered the pathway of chemical weathering. The complexity of a multiple-step pedogenic history also highlights the fact that interpretation of relative profile development as a function of time can be problematic. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.