| Abstract | This report proposes a hierarchical scheme of sedimentary facies applicable to the Lower Cretaceous rocks of the Missisauga and Logan Canyon formations in the Scotian Basin. This succession hosts the
major gas discoveries in the basin. The eleven facies, each of which is divided into several subfacies, are: 0 - delta front sandstone-mudstone turbidites; 1 - open shelf fossiliferous shales; 2 - shoreface sandstones and mudstones; 3 - intervals of
condensed sedimentation (principally during transgressions); 4 - tidal estuary to fluvial sandstones; 5 - intertidal to subtidal sandy to mixed flats; 6 - intertidal muddy to mixed flats; 7- tidal marsh lignite or carbon-rich mud; 8 - lagoonal muds;
9 - river mouth to prodelta sandstone turbidites; 10 - highly deformed sediments.
These facies have been applied to long logged sections of conventional core in the following wells: Alma K-85, Alma F-67, Cohasset A-52, Como P-21, Glenelg E-58,
Glenelg E-58A, Glenelg H-59, Glenelg N-49, Kegeshook G-67, North Triumph G-43; Panuke B-90,
Tantallon M-41, Thebaud C-74, Thebaud I-93, Venture B-13, Venture B-52, and Venture H-22.
Three characteristic vertical successions of facies are
recognized: prodelta, shoreface, and tidal parasequences. The prodelta parasequence is found in both inboard and outboard wells, however it is the dominant parasequence in outboard wells (e.g., Alma and Glenelg fields). Tidal parasequences are common
in inboard wells (Cohassett A-52, Como P-21, Kegeshook G-67, and Panuke B-90) but are also found in wells farther outboard (North Triumph G-43, Thebaud I-93, Venture B-52, and Glenelg N-49). Shoreface parasequences are generally foundwithin more
inboard wells including Cohasset A-52, Panuke B-90, Thebaud I-93, and Venture B-13 and B-52.
This facies scheme is general enough to apply to both inboard and outboard wells in the Scotian Basin, while having enough subfacies to capture details
within each depositional environment. |