Advertisement

Clays and Clay Minerals

, Volume 39, Issue 6, pp 622–633 | Cite as

Chlorite Vermiculitization and Pyroxene Etching in an Aeolian Periglacial Sand Dune, Allen County, Indiana

  • Scott Argast
Article

Abstract

Weathering has etched and deeply-denticulated the constituent orthopyroxenes, and chlorite has been transformed to vermiculite in the upper 3 m of an aeolian, periglacial sand dune formed in northeastern Indiana about 13,000 b.p. Pyroxene weathering begins with the development of cleavage-parallel etch pits on {010} and {100} surfaces. These pits coalesce and eventually crop out on basal surfaces as denticulations. The mean denticulation size increases logarithmically toward the surface, and the denticulation size of the orthopyroxenes is a quantifiable feature of the weathering process. Ferruginous pendants, microboxworks of iron oxides, and other indications of iron redeposition within the ortho-pyroxene microenvironments were not observed.

Chlorite in the dune has been weathered to vermiculite. The parent chlorite is a high-Fe variety, and the transformation to vermiculate does not involve the development of a chlorite/vermiculite intermediary phase. Fe2+ is oxidized as part of the transformation process and this iron is retained in the sediment as discrete goethite and as crystalline and noncrystalline coatings on the dune grains. The vermiculite from depths shallower than 64 cm is only partly expandable and is completely collapsed by K-saturation or heat treatment. This is a hydroxy-Al vermiculite and its formation is typical of intense weathering under the acid conditions prevalent at the dune surface.

Key Words

Chlorite Denticulations Dunes Etching Hydroxy-Al Indiana Pleistocene Pyroxene Vermiculite Weathering 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Anand, R. R. and Gilkes, R. J. (1984) Weathering of hornblende, plagioclase and chlorite in meta-dolerite, Australia: Geoderma 34, 261–280.CrossRefGoogle Scholar
  2. April, R.H., Hluchy, M.M., and Newton, R.M. (1986) The nature of vermiculite in Adirondack soils and tills: Clays & Clay Minerals 34, 549–556.CrossRefGoogle Scholar
  3. Bain, D. C. (1977) The weathering of chloritic minerals in some Scottish soils. Jour. Soil Sci., 28, 144–164.CrossRefGoogle Scholar
  4. Berner, R. A. and Schott, J. (1982) Mechanism of pyroxene and amphibole weathering II. Observations of soil grains: Amer. Jour. Sci. 282, 1214–1231.CrossRefGoogle Scholar
  5. Berner, R. A., Sjoberg, E. L., Velbel, M. A., and Krom, M. D. (1980) Dissolution of pyroxenes and amphiboles during weathering: Science 207, 1205–1206.CrossRefGoogle Scholar
  6. Bleuer, N. K. (1974) Buried till ridges in the Fort Wayne area, Indiana, and their regional significance: Geol. Soc. Amer. Bull. 85, 917–920.CrossRefGoogle Scholar
  7. Bleuer, N. K. and Moore, M. C. (1978) Environmental Geology of Allen County, Indiana: Indiana Geol. Survey Special Report 13.Google Scholar
  8. Brown, G. and Brindley, G. W. (1980) X-ray diffraction procedures for clay mineral identification: in Crystal Structures of Clay Minerals and their X-Ray Identification, G. W. Brindley and G. Brown, eds., Mineralogical Society Monograph 5, London, 305–360.Google Scholar
  9. Coffman, C. B. and Fanning, D. T. (1975) Maryland soils developed in residuum from chloritic metabasalts having high amounts of vermiculite in sand and silt fractions: Soil Sci. Soc. Amer. Proc. 39, 723–732.CrossRefGoogle Scholar
  10. Douglas, L. A. (1977) Vermiculites: in Minerals in Soil Environments, J. B. Dixon and S. B. Weed, eds., Soil Sci. Soc. Amer., Madison, Wisconsin, 259–292.Google Scholar
  11. Eggleston, C. M., Hochella, M. F., Jr., and Parks, G. A. (1989) Sample preparation and aging effects on the dissolution rate and surface composition of diopside: Geochim. et Cosmochim. Acta 53, 797–804.CrossRefGoogle Scholar
  12. Eggleton, R. A. (1975) Nontronite topotaxial after hedenbergite: Am. Mineral. 60, 1063–1068.Google Scholar
  13. Franzmeier, D. P. (1970) Particle size sorting of proglacial eolian materials: Soil Sci. Soc. Amer. Proc. 34, 920–924.CrossRefGoogle Scholar
  14. Grandstaff, D. E. (1986) The dissolution rate of forsteritic olivine from Hawaiian beach sand: in Rates of Chemical Weathering of Rocks and Minerals, S. M. Colman and D. P. Dethier, eds., Academic Press, New York, 41–59.Google Scholar
  15. Hall, R. D. and Martin, R. E. (1986) The etching of hornblende grains in the matrix of alpine tills and periglacial deposits: in Rates of Chemical Weathering of Rocks and Minerals, S. M. Colman and D. P. Dethier, eds., Academic Press, New York, 101–128.Google Scholar
  16. Hall, R. D. and Michaud, D. (1988) The use of hornblende etching, clast weathering, and soils to date alpine glacial and periglacial deposits: A study from southwestern Montana: Geol. Soc. Amer. Bull. 100, 458–467.CrossRefGoogle Scholar
  17. Holdren, G. R., Jr. and Berner, R. A. (1979) Mechanisms of feldspar weathering—I. Experimental studies: Geochim. et Cosmochim. Acta 43, 1161–1171.CrossRefGoogle Scholar
  18. Jackson, M. L. (1979) Soil Chemical Analysis—Advanced Course, 2nd ed. Published by the author, Madison, Wisconsin.Google Scholar
  19. Kirschner, F. R. and Zachary, A. L. (1969) Soil Survey of Allen County, Indiana: U.S. Dept. of Agriculture, Washington, DC.Google Scholar
  20. Landa, E. R. and Gast, R. G. (1973) Evaluation of crystalUnity in hydrated ferric oxides: Clays & Clay Minerals 21, 121–130.CrossRefGoogle Scholar
  21. Locke, W. W. (1979) Etching of hornblende grains in arctic soils: An indicator of relative age and paleoclimate: Quat. Res. 11, 197–212.CrossRefGoogle Scholar
  22. Locke, W. W. (1986) Rates of hornblende etching in soils on glacial deposits, Baffin Island, Canada: in Rates of Chemical Weathering of Rocks and Minerals, S. M. Colman and D. P. Dethier, eds., Academic Press, New York, 129–145.Google Scholar
  23. Makumbi, L. and Herbillon, A. J. (1972) Vermiculitisation experimentale d’une chlorite: Bull. Groupe franc. Argiles 24, 153–164.CrossRefGoogle Scholar
  24. Malla, P. B. and Douglas, L. A. (1987) Identification of expanding layer silicates: Layer charge vs. expansion properties: in Proc. Int. Clay Conf, Denver, 1985, L. G. Schultz, H. van Olphen and F. A. Mumpton, eds., 277–283.Google Scholar
  25. Moore, D. M. and Reynold, R. C., Jr. (1989) X-Ray Diffraction and the Identification and Analysis of Clay Minerals: Oxford University Press, Oxford, 332 pp.Google Scholar
  26. NOAA (1978) Climates of the States, Vol. 1. Alabama-Montana: Gale Research Co., Detroit, 606 pp.Google Scholar
  27. Proust, D., Eymery, J.-P., and Beaufort, D. (1986) Supergene vermiculitization of a magnesian chlorite: Iron and magnesium removal processes: Clays & Clay Minerals 34, 572–580.CrossRefGoogle Scholar
  28. Ross, G. J. (1975) Experimental alteration of chlorites into vermiculites by chemical oxidation: Nature 255, 133–134.CrossRefGoogle Scholar
  29. Ross, G. J. and Kodama, H. (1974) Experimental transformation of a chlorite into a vermiculite: Clays & Clay Minerals 22, 205–211.CrossRefGoogle Scholar
  30. Ross, G. J. and Kodama, H. (1976) Experimental alteration of a chlorite into a regularly interstratified chlorite-vermiculite by chemical oxidation: Clays & Clay Minerals 24, 183–190.CrossRefGoogle Scholar
  31. Schott, J. and Berner, R. A. (1983) X-ray photoelectron studies of the mechanism of iron silicate dissolution during weathering: Geochim., et Cosmochim. Acta 47, 2233–2240.CrossRefGoogle Scholar
  32. Schott, J. and Berner, R. A. (1985) Dissolution mechanisms of pyroxenes and olivines during weathering: in The Chemistry of Weathering, J. I. Drever, ed., Reidel, Dordrecht, 35–53.CrossRefGoogle Scholar
  33. Schwertmann, U. (1964) Differenzierung der eisenoxide des bodens durch extraktion mit ammoniumoxalat-lösung: Z. Pflanzenernahr. Dung., Bodenk. 105, 194–202.CrossRefGoogle Scholar
  34. Siever, R. and Woodford, N. (1979) Dissolution kinetics and the weathering of mafic minerals: Geochim. et Cosmochim. Acta 43, 717–724.CrossRefGoogle Scholar
  35. Stoops, G., Altemüller, H.-J., Bisdom, E. B. A., Delvigne, J., Dobrovolsky, V. V., Fitzpatrick, E. A., Paneque, G., and Sleeman, J. (1979) Guidelines for the description of mineral alterations in soil micromorphology: Pédologie 29, 121–135.Google Scholar
  36. Sunderman, J. A. (1987) Fort Wayne, Indiana: Paleozoic and Quaternary geology: in Centennial Field Guide, Vol. 3. North-Central Section, D. L. Biggs, ed., Geol. Soc. Amer., Denver, Colorado, 325–332.CrossRefGoogle Scholar
  37. Velbel, M. A. (1989) Weathering of hornblende to ferruginous products by a dissolution-reprecipitation mechanism: Clays & Clay Minerals 37, 515–524.CrossRefGoogle Scholar
  38. Vicente, M. A., Razzaghe, M., and Robert, M. (1977) Formation of aluminum hydroxy vermiculite (intergrade) and smectite from mica under acidic conditions: Clay Miner. 12, 101–112.CrossRefGoogle Scholar
  39. Wilson, M. J. (1986) Mineral weathering processes in podzolic soils on granitic materials and their implications for surface water acidification: Jour. Geol. Soc. London 143, 691–697.CrossRefGoogle Scholar

Copyright information

© The Clay Minerals Society 1991

Authors and Affiliations

  • Scott Argast
    • 1
  1. 1.Department of GeosciencesIndiana University-Purdue University at Fort WayneFort WayneUSA

Personalised recommendations