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Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium

Mineralogical Magazine

By:
, , ORCID iD , , , and
https://doi.org/10.1180/minmag.2008.072.1.149

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Abstract

The spatial and temporal changes in hydrology and pore water elemental and 87/86Sr compositions were used to determine contemporary weathering rates in a 65 to 226 ky old soil chronosequence formed from granitic sediments deposited on marine terraces along coastal California. Cl-corrected Na, K and Si increased with depth denoting inputs from the weathering of plagioclase and K-feldspar. Solute 87/86Sr exhibited progressive mixing of sea water-dominated precipitation with inputs from less radiogenic plagioclase. Linear approximations to these weathering gradients were used to determine plagioclase weathering rates of between 0.38 and 8.9×10−15 moles m−2 s−1. The lack of corresponding weathering gradients for Ca and Sr indicated short-term equilibrium with the clay ion exchange pool which requires periodic resetting by natural perturbations to maintain continuity, in spite of soil composition changes reflecting the effects of long-term weathering.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium
Series title:
Mineralogical Magazine
DOI:
10.1180/minmag.2008.072.1.149
Volume:
72
Issue:
1
Year Published:
2008
Language:
English
Publisher:
Mineralogical Society
Description:
5 p.
First page:
149
Last page:
153