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Influence of climate and eolian dust on the major-element chemistry and clay mineralogy of soils in the northern Bighorn basin, U.S.A.

January 1, 1990

Soil chronosequences in the northern Bighorn basin permit the study of chronologic changes in the major-element chemistry and clay mineralogy of soils formed in different climates. Two chronosequences along Rock Creek in south-central Montana formed on granitic alluvium in humid and semiarid climates over the past two million years. A chronosequence at the Kane fans in north-central Wyoming formed on calcareous alluvium in an arid climate over the past 600,000 years. Detailed analyses of elemental chemistry indicate that the soils in all three areas gradually incorporated eolian dust that contained less zirconium, considered to be chemically immobile during weathering, than did the alluvium. B and C horizons of soils in the wettest of the chronosequences developed mainly at logarithmic rates, suggesting that leaching, initially rapid but decelerating, dominated the dust additions. In contrast, soils in the most arid of the chronosequences developed at linear rates that reflect progressive dust additions that were little affected by leaching. Both weathering and erosion may cause changes with time to appear logarithmic in A horizons of soils under the moist and semiarid climatic regimes. Clay minerals form with time in the basal B and C horizons and reflect climatic differences in the three areas. Vermiculite, mixed-layer illite-smectite, and smectite form in the soils of the moist-climate chronosequence; smectite forms in the semiarid-climate chronosequence; and smectite and palygorskite form in the arid-climate chronosequence. ?? 1990.

Publication Year 1990
Title Influence of climate and eolian dust on the major-element chemistry and clay mineralogy of soils in the northern Bighorn basin, U.S.A.
DOI 10.1016/0341-8162(90)90018-9
Authors Marith C. Reheis
Publication Type Article
Publication Subtype Journal Article
Series Title Catena
Index ID 70016269
Record Source USGS Publications Warehouse
USGS Organization Geosciences and Environmental Change Science Center