Skip to Main Content
Book Chapter

Groundwater-Fed Wetland Sediments and Paleosols: It’s All About Water Table

By
Gail M. Ashley
Gail M. Ashley
Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA gmashley@rci.rutgers.edu
Search for other works by this author on:
Daniel M. Deocampo
Daniel M. Deocampo
Department of Geosciences, Georgia State University, Atlanta, Georgia 30302, USA
Search for other works by this author on:
Julia Kahmann-Robinson
Julia Kahmann-Robinson
Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798, USA
Search for other works by this author on:
Steven G. Driese
Steven G. Driese
Department of Geology, Baylor University, One Bear Place #97354, Waco, TX 76798, USA
Search for other works by this author on:
Published:
January 01, 2013

Abstract

Wetlands are continental depositional environments and ecosystems that range between ephemerally wet to fully aquatic habitats, and, thus, the character of a wetland soil is directly related to the position of the water table over seasonal and longer timescales. The sediment and paleosol records of wetlands are products of a unique setting that can be both exposed to the atmosphere and water-saturated at the same time. Wetlands tend to occupy low-gradient portions of the landscape in places where the phreatic zone is at least ephemerally exposed at the surface, and hydrophytic vegetation has an opportunity to colonize. Groundwater-fed wetlands are an end member of a continuum of waterlogged environments and are associated with localized groundwater discharge (GWD); e.g., springs and seeps that can sustain permanent saturation. Research has tended to follow one of two parallel tracks: sedimentology or pedology. An objective of this paper is to bring these two separate lines of inquiry closer together. The signature of wetland pedogenesis includes redoximorphic features, enhanced hydrolytic alteration or dissolution of soluble phases, and preservation of biotic indicators of wetland habitats. Histosols (peats) and other hydric soils (indicated by gley color and reduced minerals like pyrite and siderite) are common in sites with a permanently high water table and anaerobic conditions. Illuvial clays, in contrast, record episodes in which wetlands dry out and drainage improves sufficiently for these features to form. A case study from Holocene-age Loboi Swamp, Kenya, illustrates the importance of integrating field observations and laboratory analyses. Wetland conditions were observed through thin section micromorphology, mineralogy, bulk geochemistry, and macro- and microfossils. The record of Loboi Swamp is characterized by the juxtaposition of features indicating episodes of soil saturation alternating with those indicating desiccation. In order to extract the most information recorded in groundwater-fed wetlands, soils and sediments should be studied as part of the larger spatial and climatic frameworks in which they occur.

You do not currently have access to this article.

Figures & Tables

Contents

SEPM Special Publication

New Frontiers in Paleopedology and Terrestrial Paleoclimatology: Paleosols and Soil Surface Analog Systems

Steven G. Driese
Steven G. Driese
Search for other works by this author on:
Lee C. Nordt
Lee C. Nordt
Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798-7354, USA
Search for other works by this author on:
SEPM Society for Sedimentary Geology
Volume
104
ISBN electronic:
9781565763036
Publication date:
January 01, 2013

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal