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Interstratified 1:1–2:1 Mineral Formation in a Polygenetic Soil from Southern Ohio
Author(s) -
Jaynes W. F.,
Bigham J. M.,
Smeck N. E.,
Shipitalo M. J.
Publication year - 1989
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/sssaj1989.03615995005300060046x
Subject(s) - loess , pedogenesis , geology , vermiculite , mineralogy , weathering , mineral , clay minerals , paleosol , geochemistry , soil science , soil water , chemistry , geomorphology , paleontology , organic chemistry
A polygenetic soil from southern Ohio, formed by loess deposition on a pre‐existing Sangamon paleosol, was examined to determine if the lithologic discontinuity has affected subsequent clay‐mineral weathering or formation. Analyses of the <0.2 µm clays indicated that cation exchange capacities (CECs) and total Mg, K, and Fe contents were lowest near the interface between the loess and underlying paleosol at a depth of approximately 65 cm; in contrast, total Al contents were highest in this zone. An interstratified 1:1–2:1 mineral was identified in materials surrounding the loess‐paleosol contact and was concentrated in the 2.03 g/cm 3 ‐density fraction of the <0.2 µm clay using density‐gradient centrifugation. Alkylammonium exchange of the 2.03 g/cm 3 ‐density fraction demonstrated that the 2:1 component of the interstratified mineral was heterogeneous in charge and included layers characteristic of both smectite and vermiculite. Soil properties and depth distribution of the interstratified mineral suggest a pedogenic origin.