Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-26T18:29:20.167Z Has data issue: false hasContentIssue false
  • English
  • Français

Scanning Electron Microscope Morphology of Deeply Weathered Granite

Published online by Cambridge University Press:  01 July 2024

R. J. Gilkes ,
Anchalee Suddhiprakarn  and
T. M. Armitage
R. J. Gilkes
Affiliation:
Department of Soil Science and Plant Nutrition, University of Western Australia, Nedlands, Western Australia, 6009
Anchalee Suddhiprakarn*
Affiliation:
Department of Soil Science and Plant Nutrition, University of Western Australia, Nedlands, Western Australia, 6009
T. M. Armitage
Affiliation:
Department of Soil Science and Plant Nutrition, University of Western Australia, Nedlands, Western Australia, 6009
*
1Permanent address: Department of Soils, Kasetsart University, Bangkok, Thailand
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Laterite profiles developed from granite in southwestern Australia were studied by scanning electron microscopy. The morphology of soil materials reflects the mineralogy of secondary minerals formed from feldspar. In the saprolite, etched feldspar surfaces are coated with kaolinite or radiating, spherical aggregates of tubular halloysite. In the lower pallid zone these minerals have replaced most of the feldspar. In the upper pallid zone a porous framework has developed consisting mainly of quartz and gibbsite with 5-/μm euhedral gibbsite crystals in voids. Halloysite crystals in the upper pallid zone are partly unrolled and have splayed ends. Differences in mineralogy and morphology between profiles are thought to be due to variations in the intensity of leaching.

Резюме

Резюме

С помощью электронного сканирующего микроскопа изучались латеритные разрезы, развившиеся в результате выветривания гранита в юго-западной Австралии. Морфология почвенных материалов отражает минералогию вторичных минералов, образованных из полевого шпата. В сапролите, выветрелые поверхности полевого шпата покрыты каолинитом или лучевыми, сферическими агрегатами трубчатого галлуазита. В нижней, паллидной зоне эти минералы почти полностью заместили полевой шпат. В верхней паллидной зоне образовалась пористая структура, состоящая в основном из кварца и гиббсита с 5 μм идиоморфными кристаллами гиббсита в полостях. Галлуазитовые кристаллы в верхних паллидных зонах частично развернуты и имеют скошенные концы. Различия в минералогии и морфологии разрезов объясняется изменением интенсивности выщелачивания. [N. R.]

Resümee

Resümee

Lateritprofile, die sich im südwestlichen Australien im Granit gebildet haben, wurden mittels Rasterelektronenmikroskopie untersucht. Die Morphologie des Bodenmaterials zeigt die Mineralogie der Sekundärminerale, die sich aus Feldspat gebildet haben. Im Rückstandsgestein sind geätzte Feldspatoberflächen mit Kaolinit oder radial strahligen Aggregaten aus röhrenförmigem Halloysit überzogen. In der tieferen bleichen Zone haben diese Minerale fast den ganzen Feldspat ersetzt. In der oberen bleichen Zone hat sich ein poröses Gerüst gebildet, das hauptsächlich aus Quarz und Gibbsit besteht, mit 5 μm großen idiomorphen Gibbsitkristallen in den Hohlräumen. Die Halloysitkristalle in der oberen bleichen Zone sind teilweise entrollt und haben nach außen gebogene Enden. Die Unterschiede in der Mineralogie und Morphologie der einzelnen Profile werden auf eine verschieden starke Auslaugung zurückgeführt. [U. W.]

Résumé

Résumé

Des proflies de latérite développés à partir de granite en Australie du sud ouest ont été étudiés par microscopie électronique balayante. La morphologie des matériaux du sol réflète la minéralogie des minéraux secondaires formés à partir de feldspar. Dans la saprolite, des surfaces de feldspar gravées sont recouvertes de kaolinite ou d'aggrégats sphériques et branchants d'halloysite tabulaire. Dans la zone inférieure pâle, ces minéraux ont remplacé la plupart des feldspars. Dans la zone pâle supérieure, une charpente poreuse s'est développée consistant surtout de quartz et de gibbsite avec des cristaux euhédraux de 5μm de gibbsite dans les vides. Les cristaux d'halloysite dans la zone pâle supérieure sont partiellement déroulés et ont des bouts ébrasés. On croit que les différences de minéralogie et de morphologie entre les profiles sont dues à des variations dans l'intensité du lessivage. [D. J.]

Keywords

FeldsparGibbsiteGraniteHalloysiteKaoliniteScanning electron microscopyWeathering
Type
Research Article
Information
Clays and Clay Minerals , Volume 28 , Issue 1 , February 1980 , pp. 29 - 34
Copyright
Copyright © Clay Minerals Society 1980

References

Bardossy, G. Csanady, A. and Csordas, A., (1978) Scanning electron microscope study of bauxites of different ages and origins Clays & Clay Minerals 26 245–262.CrossRefGoogle Scholar
Diamond, S. and Bloor, J. W., (1970) Globular cluster micro-structure and endellite (hydrated halloysite) from Bedford, Indiana Clays & Clay Minerals 18 309–312.CrossRefGoogle Scholar
Eswaran, H. and Bin, W. C., (1978) A study of a deep-weathering profile on granite in peninsular Malaysia. I. Physico-chemical and micromorphological properties Soil Sci. Soc. Amer. J. 42 144–149.CrossRefGoogle Scholar
Eswaran, H. and Bin, W. C., (1978) A study of a deep-weathering profile on granite in Peninsular Malaysia. III. Alteration of feldspars Soil Sci. Soc. Amer. J. 42 154–158.CrossRefGoogle Scholar
Eswaran, H. Stoops, G. and Sys, C., (1977) The micromorphology of gibbsite forms in soils J. Soil Sci. 28 136–143.CrossRefGoogle Scholar
Gilkes, R. J. Scholz, G. and Dimmock, G. M., (1973) Lat-eritic deep-weathering of granite J. Soil Sci. 24 523–536.CrossRefGoogle Scholar
Gilkes, R. J. and Suddhiprakarn, A., (1979) Magnetite alteration in deeply-weathered adamellite J. Soil Sci. .CrossRefGoogle Scholar
Gilkes, RJ and Suddhiprakarn, A., (1979) Biotite alteration in deeply weathered granite. I. Morphological, mineralogi-cal and chemical properties Clays & Clay Minerals 27 349–360.CrossRefGoogle Scholar
Grubb, P. L. C., (1971) Mineralogical anomalies in the Darling Ranges bauxites at Jarrahdale, Western Australia Econ. Geol. 66 1005–1016.CrossRefGoogle Scholar
Herbert, E. J. Shea, SR and Hatch, AB, (1978) Salt content of lateritic profiles in the Yarragil Catchment, Western Australia .Google Scholar
Hsu, P. H., Dixon, J. B. and Weed, S. B., (1977) Aluminum hydroxides and oxyhydroxides Minerals in Soil Environments Madison, Wisconsin Soil Sci. Soc. Amer. 99–143.Google Scholar
Keller, W. D., (1976) Scan electron micrographs of kaolins collected from diverse environments of origin Clays & Clay Minerals 24 107–113.CrossRefGoogle Scholar
Keller, W. D., (1977) Scan electron micrographs of kaolins collected from diverse environments of origin. IV. Georgia kaolin and kaolinizing source rocks Clays & Clay Minerals 25 311–345.CrossRefGoogle Scholar
Krinsley, D. H. and Doornkamp, J. C., (1973) Atlas of Quartz Sand Surface Textures Cambridge University Press.Google Scholar
Little, I. P. Armitage, T. M. and Gilkes, R. J., (1978) The weathering of quartz in dune sands under sub-tropical conditions in southeastern Australia Geoderma 20 225–237.CrossRefGoogle Scholar
Sadleir, S. B. and Gilkes, R. J., (1976) Development of bauxite in relation to parent material near Jarrahdale, Western Australia J. Geol. Soc. Aust. 23 333–344.CrossRefGoogle Scholar