Trace element geochemistry of a thick till and clay-rich aquitard sequence, Saskatchewan, Canada. Trace element geochemistry of a thick till and clay-rich aquitard sequence, Saskatchewan, Canada. Abstract Samples collected from a 170 m borehole penetrating till, bentonitic clay, and sand at the Birsay site, Saskatchewan, Canada. has been studied as a first step for understanding the controls on dissolution and transport of trace elements, including REEs, ill porewaters of a clay-rich aquitard. The REE budgets of the till, clay, and sand are dominated by apatite and monazite, with sporadic zircon and Y-phosphate.
Apatites feature maxima at Eu-Gd.
Consequently the complex patterns arise from variable modal proportions of apatite, monazite, and plagioclase feldspar. These compositional relationship stem from relatively high proportions of quartz and carbonate, but low modal abundances of ferromagnesian and Ti-oxide minerals. The major and trace element composition is similar to continental are andesites, and the clay is interpreted to have a mixed provenance of are andesite and eroded underlying sands. The silicious Ardkenneth sand has lower concentrations of REE and most trace elements compared to the clay, but the most fractionated REE patterns. The clay and till have inherited more subdued REE patterns in part from the underlying sand unit.