DISTRIBUTION OF TRACE ELEMENTS BETWEEN CLAYS AND ZEOLITES AND AQUEOUS SOLUTIONS SIMILAR TO SEA WATER

Abstract

The mechanisms of solid-solution partitioning during mineral crystallization in sea water have been investigated for Rb, Cs, Co, Sr, U, Th and lanthanides as trace elements, and Fe, Mg-chlorite/smectites and Na-zeolites as solid phases. These minerals have been synthesized by alteration at 40°C in saline solutions of silicate glasses of appropriate compositions. The variation of the distribution coefficients (D) with the concentration of the elements as well as competition mechanisms between elements of analogous crystallochemical properties have been studied. The “trapping” of trace elements is shown to be governed by two mechanisms, according to D values or to water-rock ratios. At low values of D the incorporation of elements is controlled only by D, whereas at high values it is controlled by the number of available crystallochemical sites.