Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium
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.
Citation Information
Publication Year | 2008 |
---|---|
Title | Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium |
DOI | 10.1180/minmag.2008.072.1.149 |
Authors | A. F. White, M. S. Schulz, David A. Stonestrom, D.V. Vivit, J. Fitzpatrick, T. Bullen |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Mineralogical Magazine |
Index ID | 70033138 |
Record Source | USGS Publications Warehouse |