Hostname: page-component-77c89778f8-m8s7h Total loading time: 0 Render date: 2024-07-21T12:20:10.271Z Has data issue: false hasContentIssue false
  • English
  • Français

Assessment of Pedogenic Gibbsite as a Paleo-PCO2 Proxy Using a Modern Ultisol

Published online by Cambridge University Press:  01 January 2024

Jason C. Austin  and
Paul A. Schroeder
Jason C. Austin*
Affiliation:
Department of Geology, University of Georgia, 30602-2501, Athens, GA, USA
Paul A. Schroeder
Affiliation:
Department of Geology, University of Georgia, 30602-2501, Athens, GA, USA
*
*E-mail address of corresponding author: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The stable carbon isotope composition of CO2 occluded in the gibbsite structure is proposed as a potential atmospheric paleo-PCO2 proxy. Analysis of pedogenic gibbsite from a modern Ultisol in the Piedmont of Georgia, USA, was conducted to test the basis for this concept and to help constrain the parameters used to describe physical and biological processes affecting such factors as the respiration rate of CO2. Co-variation of the δ13C and δ18O values with depth along a gradient parallel to the mixing line between the atmosphere and the soil organic material implies that diffusion is the process that determines the stable isotope composition of soil CO2. In the upper 40 cm, the measured δ13C values are not consistent with the expected diffusive depth profile assumed in paleo-PCO2 models. The isotope signature is reset downward in the depth profile with a concentration of the most atmosphere-like δ13C and δ18O values occurring at the top of the Bt horizon by some as-yet-unknown process. Bioturbation, recrystallization, and physical translocation are potential explanations for this observation. Regardless of the process at work, the net effect is an apparent two-component mixing curve between the top of the Bt horizon and deep within the saprolite. In cases where the A horizon is eroded but the Bt horizon is preserved it is possible that δ13C values of gibbsite-occluded CO2 can serve as a proxy for atmospheric paleo-PCO2. Careful textural study of all paleosols is therefore essential to match stable carbon isotope signatures with the horizons preserved. Understanding of modern dynamics and preservation of these isotopic signatures may also be important for those that employ other carbonate proxies.

Keywords

Paleo-PCO2 ProxiesPedogenic GibbsiteSoil CO2 DiffusionStable Carbon IsotopesStable Oxygen IsotopesUltisol
Type
Article
Information
Clays and Clay Minerals , Volume 62 , Issue 4 , August 2014 , pp. 253 - 266
Copyright
Copyright © Clay Minerals Society 2014

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Austin, J.C., 2011 Soil CO2 efflux simulations using Monte Carlo method and implications for recording paleo-atmospheric PCO2 in pedogenic gibbsite Palaeogeography Palaeoclimatology Palaeoecology 305 280–285.CrossRefGoogle Scholar
Bacon, A.R. Richter, D.D. Bierman, P. and Rood, D.H., 2012 Coupling meteoric 10Be with pedogenic losses of 9Be to improve soil residence time estimates on an ancient North American interfluve Geology 40 847–850.CrossRefGoogle Scholar
Berner, R.A. and Kothavala, Z., 2001 GEOCARB III: A revised model of atmospheric CO2 over Phanerozoic time American Journal of Science 301 182–204.CrossRefGoogle Scholar
Bowen, G.J. and Beerling, D.J., 2004 An integrated model for soil organic carbon and CO2: Implications for paleosol carbonate pCO2 paleobarometry Global Biogeochemical Cycles 18 1021–1012.CrossRefGoogle Scholar
Breecker, D.O. Sharp, Z.D. and McFadden, L.D., 2009 Seasonal bias in the formation and stable isotopic compostition of pedogenic carbonate in modern soils from central New Mexico, USA Geological Society of America Bulletin 121 630–640.CrossRefGoogle Scholar
Cerling, T.E., 1984 The stable isotopic composition of modern soil carbonate and its relationship to climate Earth and Planetary Science Letters 71 229–240.CrossRefGoogle Scholar
Cerling, T.E., 1991 Carbon dioxide in the atmosphere: evidence from Cenozoic and Mesozoic Paleosols American Journal of Science 291 377–400.CrossRefGoogle Scholar
Cerling, T.E. Quade, J. and Bowman, J.R., 1989 Carbon isotopes in soils and palaeosols as ecology and palaeoecology indicators Nature 341 138–139.CrossRefGoogle Scholar
Chen, Q. Zhu, R. and Xu, H., 2013 Stable isotopes of carbon dioxide in the marine atmosphere along a hemispheric course from China to Antartica Atmospheric Environment 80 342–346.CrossRefGoogle Scholar
Cuntz, M. Ciais, P. Hoffmann, G. and Knorr, W., 2003 A comprehensive global three-dimensional model of δ18O in atmospheric CO2: 1. Validation of surface processes Journal of Geophysical Research 108 4528, doi: 10.Google Scholar
Farrimond, P. Eglinton, G. and Brassell, S.C., 1986 Alkenones in Cretaceous black shales, Blake-Bahama Basin, western North Atlantic Organic Geochemistry 10 897–903.CrossRefGoogle Scholar
Francey, R.J. Allison, C.E. Etheridge, D.M. Trudinger, C.M. Enting, I.G. Leuenberger, M. Langerfelds, R.L. Michel, E. and Steele, L.P., 1999 A 1000-year high precision record of δ13C in atmospheric CO2 Tellus 51B 170–193.CrossRefGoogle Scholar
Freeman, K.H. and Hayes, J.M., 1992 Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO2 levels Global Biogeochemical Cycles 6 185–198.CrossRefGoogle ScholarPubMed
Hesterberg, R. and Siegenthaler, U., 1991 Production and stable isotopic composition of CO2 in a soil near Bern, Switzerland Tellus 43B 197–205.CrossRefGoogle Scholar
Hsieh, J.C.C. Savin, S.M. Kelly, E.F. and Chadwick, O.A., 1998 Measurement of soil-water δ18O values by direct equilibration with CO2 Geoderma 82 255–268.CrossRefGoogle Scholar
Kump, L.R. and Arthur, M.A., 1999 Interpreting carbonisotope excursions: carbonates and organic matter Chemical Geology 161 181–198.CrossRefGoogle Scholar
Kurschner, W.M. Van Der Burgh, J. Visscher, H. and Dilcher, D.L., 1996 Oak leaves as biosensors of late Neogene and early Pleistocene paleoatmospheric CO2 concentrations Marine Micropaleontology 27 299–312.CrossRefGoogle Scholar
Marlowe, I.T. Brassell, S.C. Eglinton, G. and Green, J.C., 1990 Long-chain alkenones and alkyl alkenoates and the fossil coccolith record of marine sediments Chemical Geology 88 349–375.CrossRefGoogle Scholar
Miller, J.B. Yakir, D. White, J.W.C. and Tans, P.P., 1999 Measurement of 18O/16O in the soil-atmosphere CO2 flux Global Biogeochemical Cycles 13 761–774.CrossRefGoogle Scholar
Pagani, M. Freeman, K.H. and Arthur, M.A., 1999 Late Miocene atmospheric CO2 concentrations and the expansion of C4 grasses Science 285 876–879.CrossRefGoogle Scholar
Robertson, S.M., 1968 Soil Survey of Clarke and Oconee Counties, Georgia U.S.A. Department of Agriculture.Google Scholar
Royer, D.L. Berner, R.A. and Beerling, D.J., 2001 Phanerozoic atmospheric CO2 change: evaluating geochemical and paleobiological approaches Earth Science Reviews 54 349–392.CrossRefGoogle Scholar
Schroeder, P.A. and Melear, N.D., 1999 Stable carbon isotope signatures preserved in authigenic gibbsite from a forested granitic-regolith: Panola Mountain, Georgia, USA Geoderma 91 261–279.CrossRefGoogle Scholar
Schroeder, P.A. Melear, N.D. Bierman, P. Kashgarian, M. and Caffee, M.W., 2001 Apparent gibbsite growth ages for regolith in the Georgia Piedmont Geochimica et Cosmochimica Acta 65 381–386.CrossRefGoogle Scholar
Schroeder, P.A. Austin, J.C. and Dowd, J.F., 2006 Estimating long-term soil respiration rates from carbon isotopes occluded in gibbsite Geochimica et Cosmochimica Acta 70 5692–5697.CrossRefGoogle Scholar
Stern, L. Baisden, W.T. and Amundson, R., 1999 Processes controlling the oxygen isotope ratio of soil CO2: Analytic and numerical modeling Geochimica et Cosmochimica Acta 63 799–814.CrossRefGoogle Scholar
Su, C.M. and Suarez, D.L., 1997 In situ infrared speciation of absorbed carbonate on aluminum and iron oxide Clays and Clay Minerals 45 814–825.CrossRefGoogle Scholar
Tabor, N.J. and Yapp, C.J., 2005 Incremental vacuum dehydration-decarbonation experiments on a natural gibbsite (α-Al(OH)3): CO2 abundance and δ13C values Geochimica et Cosmochimica Acta 69 519–527.CrossRefGoogle Scholar
Van Der Burgh, J. Visscher, H. Dilcher, D.L. and Kurschner, W.M., 1993 Paleoatmospheric signatures in Neogene fossil leaves Science 260 1788–1790.CrossRefGoogle ScholarPubMed
Welp, L.R. Keeling, R.F. Meijer, H.A.J. Bollenbacher, A.F. Piper, S.C. Yoshimura, K. Francey, R.J. Allison, C.E. and Wahlen, M., 2011 Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Nino Nature 477 579–582.CrossRefGoogle ScholarPubMed
Woodward, F.I. and Bazzaz, F.A., 1988 The responses of stomatal density to CO2 partial pressure Journal of Experimental Botany 39 1771–1781.CrossRefGoogle Scholar
Yapp, C.J., 1997 An assessment of isotopic equilibrium in goethites from a bog iron deposit in a lateritic regolith Chemical Geology 135 159–171.CrossRefGoogle Scholar
Yapp, C.J., 2003 A model for 18O/16O variations in CO evolved from goethite during the solid-state α-FeOOH to α-Fe2O3 phase transition Geochimica et Cosmochimica Acta 67 1991–2004.CrossRefGoogle Scholar
Yapp, C.J. and Poths, H., 1986 Carbon in natural goethites Geochimica et Cosmochimica Acta 50 1213–1220.CrossRefGoogle Scholar
Yapp, C.J. and Poths, H., 1990 Infrared spectral evidence for a minor Fe(III) carbonate bearing component in natural goethite Clays and Clay Minerals 38 442–444.CrossRefGoogle Scholar
Yapp, C.J. and Poths, H., 1992 Ancient atmospheric CO2 pressures inferred from natural goethites Nature 355 342–344.CrossRefGoogle Scholar
Yapp, C.J. and Poths, H., 1996 Carbon isotopes in continental weathering environments and variations in ancient atmospheric CO2 pressure Earth and Planetary Science Letters 137 71–82.CrossRefGoogle Scholar