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), 1319-1328.

『長石表面の風化微環境:土壌の流体−鉱物反応を理解することとの関係』


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 micrometers 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.

Keywords: alkali feldspar; TEM; smectite; weathering.』

Introduction
Methodology
 Soils and their mineralogy
 SEM, FIB and TEM
Results
 Bare grain surfaces
 Coated grain surfaces
Discussion
Conclusions
Acknowledgements
References


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