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Sericites in Feldspars as Source of 2:1 Phyllosilicates in Selected Sandy Soils
Author(s) -
Arocena J. M.,
Pawluk S.,
Dudas J. M.
Publication year - 1993
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1993.03615995005700060038x
Subject(s) - orthoclase , feldspar , albite , microcline , sericite , eluvium , mineralogy , geology , weathering , clay minerals , soil water , plagioclase , geochemistry , soil science , quartz , paleontology
The high content of 2:1 phyllosilicates in the eluvial horizon of many sandy forested soils in North America is attributed to extraneous deposition. In this study, we evaluated the hypothesis that sericite in feldspars is a local source of 2:1 phyllosilicate by investigation of thin sections and coarse sand fractions from three pedons in an Alfisol‐Spodosol association developed on Quaternary sandy deposits in Alberta. In situ investigation of the alteration products of feldspar weathering was conducted by using x‐ray microdiffraction techniques, light and electron microscopy, and layer charge density by alkyl ammonium saturation technique. The nature of the minerals in the bulk samples and total elemental composition of the sand fractions were also investigated. Results showed that feldspars occur as orthoclase, microcline, and albite. Some of the feldspar grains were perthitic in nature. The weathering of feldspars is characterized by linear striations (parallel and cross linear) and starts mainly from grain fractures and twin planes. Several types of 2:1 phyllosilicates were identified in the alteration products: (i) a component with a fixed basal spacing around 1.0 nm, (ii) a high‐charge component with a charge density of about 0.6 mol c [(Si, Al) 4 O 10 ] −1 , (iii) a low‐charge component with charge density of about 0.34 mol c [(Si, Al) 4 O 10 ] −1 , and (iv) an interstratified component comprising of both the low‐ and high‐charge components.