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PALEOCLIMATIC APPLICATIONS AND MODERN PROCESS STUDIES OF PEDOGENIC SIDERITE GREG A. LUDVIGSON Kansas Geological Survey, The University of Kansas, 1930 Constant Avenue, Lawrence, Kansas 66047-3724, USA e-mail: gludvigson@kgs.ku.edu LUIS A. GONZÁLEZ, DAVID A. FOWLE, AND JENNIFER A. ROBERTS Department of Geology, The University of Kansas, 1475 Jayhawk Boulevard, Room 120, Lawrence, Kansas 66045-7594, USA STEVEN G. DRIESE Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798-7354, USA MARK A. VILLARREAL AND JON J. SMITH Kansas Geological Survey, The University of Kansas, 1930 Constant Avenue, Lawrence, Kansas 66047-3724, USA AND MARINA B. SUAREZ Department of Geological Sciences, University of Texas at San Antonio, 1 UTSA Circle, San Antonio, Texas 78249, USA ABSTRACT: Pedogenic siderite is a carbonate mineral that forms in the reducing groundwaters of poorly drained soils and paleosols in zonal climatic belts with strongly positive precipitation–evaporation balances. Microcrystalline and spherulitic forms of siderite are commonly recognized in micromorphologic studies of hydromorphic paleosols. Ancient paleosol sphaerosiderites commonly occur with diameters in excess of 1 mm, while modern pedogenic siderite crystal dimensions in excess of 100 µm are rare. Pedogenic siderites have been widely reported from Late Paleozoic, Mesozoic, and Cenozoic paleosols. The carbon and oxygen isotopic compositions of pedogenic siderites have been widely used as proxies for the oxygen isotopic composition of paleoprecipitation for their respective paleosols. Modern process studies of historic pedogenic siderites are yielding a more refined understanding of the stable isotopic systematics of low-temperature siderite. These works will lead to a future change in usage of published siderite–water 18 O fractionation equations.
MULTIANALYTICAL PEDOSYSTEM APPROACH TO CHARACTERIZING AND INTERPRETING THE FOSSIL RECORD OF SOILS LEE C. NORDT Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798, USA e-mail: Lee_Nordt@baylor.edu CHARLES T. HALLMARK Department of Soil and Crop Sciences, Texas A&M University, 370 Olsen Blvd., College Station, Texas 77843, USA STEVEN G. DRIESE AND STEPHEN I. DWORKIN Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798, USA ABSTRACT: Interpretations of critical zones, past and present, are dependent on the comprehensive characterization of morphological, physical, chemical, biological, and mineralogical properties of soils as the biogeochemical mediator of Earth’s surface processes. The traditional approach of studying fossil soils (paleosols), however, is modeled after methods developed during the advent of pedology in the early 20th century. Even though there have been remarkable advances in the development of analytical procedures for modern soils (pedology), advancements in paleopedology have not proceeded past wholerock geochemical characterization. Here, we develop multianalytical strategies combining traditional and modern approaches to studying paleosols that include direct laboratory measurement, petrographic analysis, and pedotransfer functions. In addition to standardizing the characterization of paleosols, doing so will also contribute to more robust geoinformatic compilations and strengthen interpretations of soil processes, soil taxonomic classification, edaphic controls, and climate conditions in the past. We applied the multianalytical approach to a paleosol from the Late Triassic and demonstrate that it classifies as a Vertisol based on slickensides identified in the field, sepic fabric in thin section, and high values for variables such as total and fine clay content, coefficient of linear extensibility (COLE), smectite content, and available water capacity (AWC). Reconstructed cation exchange capacity (CEC), pH, and base saturation point to a plentiful supply of plant available nutrients. Most reconstructed properties appear to have been reasonably preserved because of shallow burial depths and the formation of slowly permeable claystones. Further testing of direct analytical techniques and the development of pedotransfer functions beyond Vertisols are needed to improve the characterization of the full range of properties expected in the fossil rock record of soils.
Page 2 and 3: New Frontiers in Paleopedology and
Page 4 and 5: A SHORT HISTORY AND LONG FUTURE FOR
Page 6 and 7: CO 2 CONCENTRATIONS IN VERTISOLS: S
Page 8 and 9: SOIL AND LANDSCAPE MEMORY OF CLIMAT
Page 12 and 13: ALLUVIAL STACKING PATTERN ANALYSIS
Page 14 and 15: PROGRADING DISTRIBUTIVE FLUVIAL SYS
Page 16 and 17: SOIL DEVELOPMENT ON MODERN DISTRIBU
Page 18 and 19: A PEDOSTRATIGRAPHIC APPROACH TO NON
Page 20 and 21: oth higher temperatures and an inte
Page 22: EARLY CAMBRIAN HUMID, TROPICAL, COA

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