M. S. Schulz David A. Stonestrom D.V. Vivit J. Fitzpatrick T. Bullen A. F. White 2008 <p><span>The spatial and temporal changes in hydrology and pore water elemental and&nbsp;</span>^87/86<span>Sr 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<span>&nbsp;</span></span>^87/86<span>Sr 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</span>⁻¹⁵<span><span>&nbsp;</span>moles m</span>⁻²<span><span>&nbsp;</span>s</span>⁻¹<span>. 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.</span></p> application/pdf 10.1180/minmag.2008.072.1.149 en Mineralogical Society Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium article