Weathering microenvironments on feldspar surfaces: implications for understanding fluid-mineral reactions in soils

Lee, M.R. , Brown, D.J. , Hodson, M.E., MacKenzie, M. and Smith, C.L. (2008) Weathering microenvironments on feldspar surfaces: implications for understanding fluid-mineral reactions in soils. Mineralogical Magazine, 72(6), pp. 1319-1328. (doi: 10.1180/minmag.2008.072.6.1319)

Abstract

The mechanisms by which coatings develop on weathered grain surfaces, and their potential impact on rates of fluid-mineral interaction, have been investigated by examining feldspars from a 1.1 ky old soil in the Glen Feshie chronosequence, Scottish highlands. Using the focused ion beam technique, electron-transparent foils for characterization by transmission electron microscopy were cut from selected parts of grain surfaces. Some parts were bare whereas others had accumulations, a few micrometres thick, of weathering products, often mixed with mineral and microbial debris. Feldspar exposed at bare grain surfaces is crystalline throughout and so there is no evidence for the presence of the amorphous 'leached layers' that typically form in acid-dissolution experiments and have been described from some natural weathering contexts. The weathering products comprise sub-μm thick crystallites of an Fe-K aluminosilicate, probably smectite, that have grown within an amorphous and probably organic-rich matrix. There is also evidence for crystallization of clays having been mediated by fungal hyphae. Coatings formed within Glen Feshie soils after ∼1.1 ky are insufficiently continuous or impermeable to slow rates of fluid-feldspar reactions, but provide valuable insights into the complex weathering microenvironments on debris and microbe-covered mineral surfaces.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Brown, Dr David and MacKenzie, Dr Maureen and Lee, Professor Martin
• Authors: Lee, M.R., Brown, D.J., Hodson, M.E., MacKenzie, M., and Smith, C.L.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences; College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Mineralogical Magazine
• Publisher: Mineralogical Society
• ISSN: 0026-461X
• ISSN (Online): 1471-8022
• Copyright Holders: Copyright © 2008 Mineralogical Society
• First Published: First published in Mineralogical Magazine 72(6):1319-1328
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher.