Late Quaternary climate change, loess sedimentation, and soil profile development in the central Great Plains: A pedosedimentary model

Research Article| March 01, 2007 Late Quaternary climate change, loess sedimentation, and soil profile development in the central Great Plains: A pedosedimentary model Peter M. Jacobs; Peter M. Jacobs 1Department of Geography and Geology, University of Wisconsin–Whitewater, 800 W. Main St., Whitewater, Wisconsin 53190, USA Search for other works by this author on: GSW Google Scholar Joseph A. Mason Joseph A. Mason 2Department of Geography, University of Wisconsin, 550 N. Park St., Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Peter M. Jacobs 1Department of Geography and Geology, University of Wisconsin–Whitewater, 800 W. Main St., Whitewater, Wisconsin 53190, USA Joseph A. Mason 2Department of Geography, University of Wisconsin, 550 N. Park St., Madison, Wisconsin 53706, USA Publisher: Geological Society of America Received: 06 Jul 2005 Revision Received: 17 May 2006 Accepted: 09 Oct 2006 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 GEOLOGICAL SOCIETY OF AMERICA GSA Bulletin (2007) 119 (3-4): 462–475. https://doi.org/10.1130/B25868.1 Article history Received: 06 Jul 2005 Revision Received: 17 May 2006 Accepted: 09 Oct 2006 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Peter M. Jacobs, Joseph A. Mason; Late Quaternary climate change, loess sedimentation, and soil profile development in the central Great Plains: A pedosedimentary model. GSA Bulletin 2007;; 119 (3-4): 462–475. doi: https://doi.org/10.1130/B25868.1 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 Research on soil genesis often assumes a "top-down" model, in which the soil profile develops downward from a stable land surface. This model is inapplicable to upland landscapes affected by frequent dust deposition, where soils grow upward as they develop. On the central Great Plains, late Quaternary loess sections proximal to immediate source areas contain the Brady Soil, a prominent marker separating late Pleistocene Peoria Loess from Holocene Bignell Loess. Farther from immediate dust source areas, the Brady Soil and Bignell Loess are not recognizable in the field. On loess tablelands in these distal regions, surface soils typically contain a prominent, clay-rich B horizon below a thick silty A horizon. Assuming top-down pedogenesis, this could be interpreted as a postglacial soil profile formed in Peoria Loess, with the B horizon produced by weathering and clay illuviation. We propose a strikingly different interpretation, in which the upper B horizon at distal sites is the Brady Soil A horizon that has been transformed by burial, organic matter loss, and modern subsoil structure formation processes. The overlying modern A horizon represents Bignell Loess. Properties of the Brady Soil at proximal sites (a distinctive burrowed zone, high clay content and TiO2/ZrO2, and low volcanic glass content) can be traced to the B horizon in distal soils. A decrease in smectite abundance above the Brady Soil at proximal sites is identifiable at the top of the clay-rich B horizon in distal soils. The spatial variation of clay content in loess and soil horizons is best explained by eolian sedimentation patterns. The higher clay content in the Brady Soil and distal B horizons defines a fine-grained zone that represents a late phase of Peoria Loess accumulation. Evidence of chemical weathering is minimal, and illuvial clay is rare to absent in the clay-rich B horizons. Illuvial clay does often occur deep in the solum and is related to the depth below the top of the Brady Soil. The depth of occurrence of illuvial clay is not related to modern climate parameters, although depth to secondary carbonate appears to be in equilibrium with modern climate. Upland soils in the central Great Plains are composite soils; their properties are the result of a pedosedimentary history linked to regional climate change that has influenced sedimentation and pedogenesis since the late Pleistocene. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.