Chemostratigraphic and Heavy Mineral Analyses as Stratigraphic Tools in the Bowser and Sustut Basins, British Columbia, Canada
Carol Evenchick1, David
Ritcey2, Andrew Morton3,
Amelia Wright4, and Kenneth Ratcliffe4
1 Geological Survey of Canada, Vancouver, NF
2 Geological Survey of Canada, Vancouver, BC
3 HM Research Associates, Loughborough, United Kingdom
4 Chemostrat Inc, Houston, TX
The Bowser and Sustut basins, north-central British Columbia, are situated in the central Intermontaine Belt of the Canadian Cordillera. The Bowser Lake and Sustut groups contain over 5000 m and 2000 m, respectively, of Middle Jurassic to Late Cretaceous, submarine fan to fluvial sedimentary rocks. Chemostratigraphic analysis of field samples from these stratigraphic intervals, combined with heavy mineral data, demonstrates that the Sustut Group is markedly different to the Bowser Lake Group in terms of its whole rock geochemistry and heavy mineralogy and that the lithostratigraphic units within the Bowser Lake Group also display marked variations.
By integrating the evolving stratigraphic understanding of the basins with the chemostratigraphic and heavy mineral data, it is possible to demonstrate that marked changes in sediment provenance occurred both between and within the two basins. The Sustut Group sediments were derived from acid igneous and metasedimentary provenances, with little or no influence of basic igneous components, whereas, the Bowser Lake Group sediments were derived from a more mixed igneous complex. Chemostratigraphic and heavy mineral variations within the Bowser Lake Group indicate influences of acid igneous and basic igneous provenances during deposition, specifically with indication of derivation from ophiolitic complexes. By combining these findings with palaeocurrent data, petrographic data and field mapping data, it is possible to more confidently differentiate and correlate the component units of the basins, thereby allowing better understanding of basin-fill history.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005