ELEMENTAL DISTRIBUTION AND PYRITE OCCURRENCE IN A FRESH-WATER PEATLAND, ALBERTA

A continental minerotrophic peatland in Alberta was studied for its bo tanical, petrographical, mineralogical and geochemical characteristics . Changes in peat stratigraphy and mineralogy are related, and develop ment toward oligotrophic conditions is recorded. Elemental concentrati on and distribution vary in the peat profile, reflecting the influence of natural and anthropogenic factors on peat geochemistry. Many eleme nts (Al, As, Ba, Co, Cr, Fe, Mn, Th, V) accumulate in the zone of wate r table fluctuation as a result of changes in redox chemistry. The rel ative elemental concentration at the surface and near-surface (e.g., A s, Cr, Sb, Th, Ti, V) may also be attributed to atmospheric deposition related to anthropogenic activity. Chemical analysis (Al, Fe, Mg, Na, Si, Ti) also reveals the presence of a non-visible volcanic-ash rich layer near the base of the peat profile, possibly Mazama tephra. This study provides evidence of pyrite formation in a freshwater peat-formi ng environment, associated with high-sulphur peats.