Hostname: page-component-848d4c4894-wg55d Total loading time: 0 Render date: 2024-05-04T02:19:24.976Z Has data issue: false hasContentIssue false
  • English
  • Français

An Fe-Berthierine from a Cretaceous Laterite: Part II. Estimation of Eh, pH and pCO2 Conditions of Formation

Published online by Cambridge University Press:  28 February 2024

Steven J. Fritz  and
Thomas A. Toth
Steven J. Fritz
Affiliation:
Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907
Thomas A. Toth
Affiliation:
Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907
Get access Rights & Permissions [Opens in a new window]

Abstract

Transgression by the Western Interior Sea during the Late Cretaceous in southwestern Minnesota caused swampy conditions to be imposed upon a laterite consisting of gibbsite, goethite and kaolinite. Reducing conditions overprinted upon the laterite reduced ferric Fe in goethite for incorporation of ferrous Fe into Fe-berthierine. Attendant oxidation of organic matter provided CO2 for siderite's formation. Thermodynamic calculations indicate that berthierine, gibbsite, goethite, kaolinite and siderite were in equilibrium with a solution whose pH was 5.2 and whose pCO2 was on the order of 0.3 atm. Formation of Fe-berthierine is favored by solutions having: 1) low silica concentration; 2) low [Mg2+]/[Fe2+] ratio; 3) high pCO2; 4) extremely low sulfate content before reduction takes place; and 5) moderate reducing conditions (Eh around −0.05 V).

Keywords

BerthierineGibbsiteGoethiteCretaceousKaolinitepCO2pHSideriteSoil ZoneWeathering
Type
Research Article
Information
Clays and Clay Minerals , Volume 45 , Issue 4 , August 1997 , pp. 580 - 586
Copyright
Copyright © 1997, The Clay Minerals Society

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

Brookins, D.G., 1988 Eh-pH diagrams for geochemistry Berlin Springer-Verlag 10.1007/978-3-642-73093-1.CrossRefGoogle Scholar
Faure, G., 1991 Principles and applications of inorganic geochemistry New York Macmillan.Google Scholar
Flebbe, P.A. et al. , Cohen, 1984 et al. , Carbon dioxide and methane systematics in selected Okefenokee Swamp sites The Okefenokee Swamp Los Alamos, NM Wetland Surveys 380–390.Google Scholar
Kauffman, E.G., 1977 Geological and biological overview, Western Interior Basin Cretaceous facies, fauna, and paleoenvironments across the Western Interior Basin, Mountain Geologist. Rocky Mtn Assoc Geol 14 75–99.Google Scholar
Krauskopf, K., 1967 Introduction to geochemistry New York J Wiley.Google Scholar
Lindsay, W.L., 1979 Chemical equilibria in soils New York J Wiley.Google Scholar
Nordstrom, D.K. Valentine, S.D. Ball, J.W. Plummer, L.N. and Jones, B.E., 1984 Partial compilation and revision of basic data in the WATEQ programs US Geol Surv Water Res Invest 84–4186.Google Scholar
Postala, D., 1977 The Occurrence and chemical composition of recent Fe-rich mixed carbonates in a river bog J Sed Petrol 47 1089–1098.Google Scholar
Robie, R.A. Hemingway, B.S. and Fisher, J.R., 1979 Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 Pascals) pressure and at higher temperatures US Geol Surv Bull 1452.Google Scholar
Stumm, W. and Morgan, J.J., 1981 Aquatic chemistry New York J Wiley.Google Scholar
Tardy, Y. and Garrels, R.M., 1974 A method of estimating the Gibbs energies of formation of layer silicates Geochim Cosmochim Acta 38 1101–1116 10.1016/0016-7037(74)90007-6.CrossRefGoogle Scholar
1982 J Phys Chem Ref Data 11 suppl2.Google Scholar
Woods, T.L. and Garrels, R.M., 1987 Thermodynamic values at low temperature for natural inorganic materials: An uncritical summary New York Oxford Univ Pr.Google Scholar
Weast, R.C. and Astle, W.J., 1981 editors. Handbook of Chemistry and Physics Boca Raton, FL CRC Pr.Google Scholar