Diagenetic Features of Grand Rapids Formation, North-Central Alberta, Canada: ABSTRACT

摘要: The Lower Cretaceous Grand Rapids Formation of north-central Alberta consists three massive sandstone units separated by shales and siltstones. Average thickness the formation is approximately 90 m. In subsurface these sandstones are impregnated with bitumen form Wabasca oil sands deposit, resources estimated at 10.5 × 109 cu m (66 bbl). arkosic to lithic a fairly heterogeneous mineralogy in which predominant constituents quartz, feldspar, chert, rock fragments, mica, glauconite, locally siderite. They poorly consolidated, main cementing agents being authigenic clays. Kaolinite tends be dominant clay mineral oil-saturated while montmorillonite Fe-rich chlorite predominate underlying water-bearing sandstones. Scanning electron microscope studies show that kaolinite occurs as booklets, irregularly scattered throughout pore-filling habit. Montmorillonite have both pore-lining pore-bridging habits, illite mostly clay. Montmorillonite-chlorite mixed layer clays found some samples. all appear origin. Calcite only other common agent. calcareous cement formed early, apparently replacing most original matrix material forming large concretions up 5 diameter lower unit. Other minerals may local include siderite, K-feldspar, pyrite, zeolites(?). End_of_Article - Last_Page 735------------