REE PATTERNS AS A TOOL FOR RECOGNITION OF DIAGENETIC BEDS - A CASE FROM THE LOWER DEVONIAN UPPER GASPE LIMESTONES, GASPE PENINSULA, QUEBEC

Analyses of rare earth elements (REE), major elements, insoluble resid ue content and mineralogy were performed on carbonate and siliciclasti c samples from the Early Devonian Upper Gaspe Limestones in eastern Ga spe Peninsula. Siliciclastic rocks are richer in REE than coeval mecha nically deposited carbonates. A positive relationship between the abso lute amount of REE and the content of aluminosilicate is clear for mos t samples. Even if poor in aluminosilicate, diagenetic carbonate concr etions are the richest in REE. The concretions also show a significant negative Europium anomaly. Mineralogical, major element and stable is otope data show that calcite cementation resulting in the concretions was rapid and completed before reaching the methanogenic zone. Diagene tic conditions were responsible for remobilization of the REE from hos t detrital material and for raising the REE content of the concretions . The REE pattern is a potential tool for recognition of diagenetic be ds produced in various geochemical environments.