Palynologic zonation and correlation of the Peace River coalfield, northeastern British Columbia

• Main Author: Broatch, Jane Catherine
• Language: English
• Published: University of British Columbia 2010
• Subjects: Palynology > British Columbia > Peace River Region; Coal mines and mining > British Columbia > Peace River region
• Online Access: http://hdl.handle.net/2429/26173

The strata of the Peace River coalfield, in the Foothills of northeasten British Columbia, formed in a tectonically active region near the western margin of the craton. The complex pattern of intertonguing marine and non-marine strata which resulted was subsequently deformed by folding and thrusting, making interpretation and correlation extremely difficult. The present palynologic study was undertaken in an attempt to resolve some of the stratigraphic problems, where sedimentological and geophysical methods have failed. The primary aim of the study is to generate a composite palynologic section that can be used to zone, correlate and date the coal-bearing strata in the southern half of the coalfield. Eleven drill holes representing nearly 3000 meters of section from the Gething, Moosebar and Gates formations were sampled at 15 meter intervals. The 199 samples examined for palynomorphs yielded a total assemblage containing 232 pollen and spore species, 96 dinoflagellate and acritarch species and 22 algal cyst and fungal spore species. 256 of the 350 species are restricted in their occurrence within the section, and have been used to zone and correlate the strata. Open marine, restricted marine and non-marine horizons are identified on the basis of type and relative abundance of palynomorphs. Contact relationships are examined and clarified, the palynologic section is compared with lithologic information, and a geologic age is established for the rocks. The Gething Formation consists of a thin basal marine unit, overlain by a thick non-marine succession characterized by poor preservation of palynomorphs, and two clearly defined marine tongues which occur in the northern and upper half of the formation. The marine unit at the base of the unit defines the Gething-Cadomin contact. The marine tongues near the top of the formation are palyno-logically distinct from the overlying marine strata of the Moosebar Formation, and represent a unique transgressive phase. The lower half of the Moosebar Formation consists of marine shales, with an abundant and diverse assemblage of dinocysts and acritarchs, representing open marine conditions for most of this phase of deposition. The upper half of the formation consists of a palynologically barren, coarsening-upward sequence which is interpreted as a relatively high energy (non-marine) regressive phase. The Gates Formation consists of a complex pattern of intertonguing marine and non-marine strata. The lower half of the Gates is open marine in the region of Bullmoose Mt., and intertonguing marine and non-marine in the region from Wolverine River to Monkman Pass. In the southeast, the terrestrial strata occurs between two resticted marine zones which are continuous with the open marine strata to the northwest. The restricted marine unit which underlies the terrestrial strata, has been previously identified in whole or in part as the 'Torrens Member', and is considered here to be part of the Gates Formation on the basis of palynologic evidence. The basal marine/non-marine unit is overlain by a middle terrestrial and middle marine unit, and an upper terrestrial and upper marine unit. The entire Gething through Gates section is middle Albian to early late Albian in age, based on the first appearance of early angiosperm monocolpate and tricolpate grains. === Science, Faculty of === Earth, Ocean and Atmospheric Sciences, Department of === Graduate