Some geologic investigations of Quaternary deposits, especially in the conterminous United States, have attempted to use relative degrees of weathering and soil formation to establish chronosequences of glacial and (or) fluvial landforms.Most studies have been in the glacial terrane of the midcontinent and the Western United States.Few such studies have been conducted in the Eastern United States, especially in the unglaciated Middle Atlantic and Southeastern States.From 1979 to 1984, the U.S. Geological Survey and the U.S. Department of Agriculture's Soil Conservation Service conducted cooperative regional studies of the relations between soils and geology in the Middle Atlantic and Southeastern States.The primary goal of the studies was to determine if soil properties could be used to estimate ages of associated landforms.Coral, wood fragments, and peat were sampled from constructional landforms of fluvial and marine origin in order to estimate ages by isotopic analyses; these ages were then related to regional biostratigraphic and lithostratigraphic correlations.Specific site investigations were conducted on Pliocene to Holocene marine and fluvial terraces in the Atlantic and eastern Gulf Coastal Plains and the Appalachian Piedmont.Soils on granite, schist, and quartzite parent rocks of the Appalachian Piedmont were sampled to test the use of soil properties as indicators of soil age.Each chapter of this bulletin series examines the relation of soils to geology in a specific geographic area.The cooperative study involved research scientists from both agencies and field personnel from State offices of the Soil Conservation Service.Responsibility for sample analysis was divided between the Department of Agriculture's National Soil Survey Laboratory in Lincoln, Nebr., and the U.S. Geological Survey in Reston, Va.This report was prepared by scientists from both agencies who participated in specific site investigations
Research Article| January 01, 2011 Age, genesis, and paleoclimatic interpretation of the Sangamon/Loveland complex in the Lower Mississippi Valley, U.S.A. Helaine W. Markewich; Helaine W. Markewich † 1U.S. Geological Survey, 3039 Amwiler Road, Suite 130, Atlanta, Georgia 30360, USA †E-mail: helainem@usgs.gov Search for other works by this author on: GSW Google Scholar Douglas A. Wysocki; Douglas A. Wysocki 2National Soil Survey Center, 100 Centennial Mall North, Room 152, MS 34, Lincoln, Nebraska 68508, USA Search for other works by this author on: GSW Google Scholar Milan J. Pavich; Milan J. Pavich 3U.S. Geological Survey, National Center, MS 926B, Reston, Virginia 20192, USA Search for other works by this author on: GSW Google Scholar E. Moye Rutledge E. Moye Rutledge 4Emeritus Faculty, Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2011) 123 (1-2): 21–39. https://doi.org/10.1130/B30208.1 Article history received: 02 Nov 2009 rev-recd: 11 Feb 2010 accepted: 06 Apr 2010 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Helaine W. Markewich, Douglas A. Wysocki, Milan J. Pavich, E. Moye Rutledge; Age, genesis, and paleoclimatic interpretation of the Sangamon/Loveland complex in the Lower Mississippi Valley, U.S.A.. GSA Bulletin 2011;; 123 (1-2): 21–39. doi: https://doi.org/10.1130/B30208.1 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 For more than a century, the Sangamon paleosol (the Sangamon) has been an integral part of geologic and pedologic investigations in the central United States, including the Upper Mississippi and Lower Missouri River Valleys. Compositional, pedologic, micromorphologic, stratigraphic, and age data indicate that the prominent reddish paleosol developed in silt-rich deposits of the Lower Mississippi Valley, from southernmost Illinois to northwestern Mississippi, represents multiple periods of soil formation, and is wholly or in part time equivalent to the Sangamon of the central United States. Thermoluminescence data, for localities where the Sangamon developed in loess, indicate that the primary period of loess deposition was from 190 to 130 ka (oxygen isotope stage, OIS6), that loess deposition continued intermittently from 130 to 74 ka (OIS5), and that deposition was wholly or in part coeval with Loveland loess deposition in the central United States. Beryllium-10, chemical, and pedologic data indicate that in the Lower Mississippi Valley: (1) the Sangamon represents a minimum time period of 60–80 k.y.; (2) there were at least two periods of soil formation, ca. 130–90 ka and 74–58 ka (OIS4); and (3) rates of weathering and pedogenesis equaled or exceeded the net loess-accumulation rate until at least 46 ka (OIS3) and resulted in development of a paleosol in the overlying basal Roxana Silt. Along a N-S transect from southern Illinois to western Mississippi, Sangamon macroscopic characteristics as well as the micromorphology, chemistry, and mineralogy, suggest a regional paleoclimate during periods of soil formation that: (1) was warm to hot, with a wider range in temperature, precipitation, and evapotranspiration than present; (2) had seasonal to decadal or longer periods of drought; and (3) had down-valley (southward) trends of increasing temperature and precipitation and decreasing seasonality and variation in annual to decadal precipitation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Uncorrected [sup 10]Be inventories of a 2.7 m-long section of core indicate surface exposure lasting 115 ka during development of the Sangamon Geosol and 30 ka for a soil complex developed in overlying loessial sediment (Robein Silt). The latter estimate is in agreement with [sup 14]C assays in the region. Taking into account the age of overlying late Wisconsin drift, the new data indicate an age of about 170 ka for the onset of Sangamon pedogenesis in northern Illinois. Previous to this study, there have been no numerical-age determinations for the start of the last interglacial in northern IL. The data confirm a previous hypothesis that the Lake Michigan Lobe did not invade IL contemporaneous with deposition of Roxana Silt, or during the other period of midcontinental loess deposition suggest by TL ages of ca. 70 to 85 ka. The core was collected immediately south of the IL-WI border (42[degree] 30 minutes N, 88[degree] 30 minutes W) near Hebron, IL. Buried by 14 m of late Wisconsin drift, and the interval assayed for [sup 10]Be included 2.0 m of pedogenically-altered Illinoian sand and gravel, and 0.7 m of Wisconsin silt. One AMS [sup 14]C assay of carbonized fragments from themore » A-horizon of the Sangamon Geosol yielded an age of 38,500 [+-] 5,000 yr B.P.; conventional [sup 14]C ages for the overlying silt are from wood fragments (24,780 [times] 360 yr B.P.) and a bulk soil sample (26,030 [+-] 450 yr B.P.). The range of ages is typical for this stratigraphic sequence in IL. The [sup 10]Be concentration in the lowest part of the silt is 600 atoms/gm. This value is three times greater than the concentration typical of calcareous Mississippi River valley loess and of the C-horizon of the Sangamon Geosol in the core. High concentration of [sup 10]Be in the Robein Silt likely was caused by redeposition of [sup 10]Be-rich B-horizon material eroded from soil profiles elsewhere in the paleobasin.« less
Isotopes of Be and C were used to reconstruct loess accumulation, hillslope evolution, and agricultural modification in soils of western Iowa. While both elements are derived from additions by the atmosphere (via plants in the case of carbon), the differences in element cycling allow erosional and depositional processes to be separated from biochemical processing. Based on 'OBe, loess accumulation likely occurred simultaneously with hillslope degradation. Rates of loess accumulation declined five- fold between early stages (late Pleistocene and early Holocene) and later stages (late Holocene) of ac- cumulation, but the absolute timing of accumulation requires independent dating methods. Based on 14C measurements, plant inputs and decomposition are significant near the surface, but below 1-1.5 m carbon inputs are minimal and decomposition is nearly arrested. The amount of carbon below 1.5 m is constant (0.1%) and is composed of soil organic matter that was buried by loess. Agricultural modifi-
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