Fluid Compartmentalization of Devonian and Mississippian Dolostones, Western Canada Sedimentary Basin: Evidence from Fracture Mineralization

摘要

Integrated petrographic, geochemical and fluid inclusion study of fracture mineralization in Mississippian and Devonian dolostones extending from Alberta to British Columbia, Canada aims at quantifying the type and nature of fluids that precipitated diagenetic minerals and whether these fluids represent a single or multiple events. Fracture-filling saddle dolomite and calcite from three Devonian and two Mississippian carbonate successions were investigated in this study. The Devonian formations include Slave Point and Duvernay formations and the Mississippian Upper Debolt and Turner Valley formations. Isotopic evidence from dolomite cement indicate the presence of a hydrothermal fluid source. The Mississippian saddle dolomite is characterized by less depleted δ18O isotopic values, less radiogenic 87Sr/86Sr isotopic ratios and lower homogenization temperatures and salinity values of fluid inclusions compared to the Devonian saddle dolomite. These results suggest that possibly two hydrothermal pulses related to early (Antler) and late (Laramide) tectonic events affected the Western Canada Sedimentary Basin.