An integrated structural and hydrogeologic investigation of the fracture system in the Upper Cretaceous Nanaimo Group, southern Gulf Islands, British Columbia.

摘要

A detailed fracture-mapping program was undertaken on the southern Gulf Islands in southwestern British Columbia to characterise the fracture system of the Upper Cretaceous Nanaimo Group. The purpose of this study was to identify differences in fracture distribution and character with respect to lithology and different generations of geologic structures, and to apply this fracture distribution and characterisation to the development of a conceptual model for fractured controlled groundwater. A total of over 8000 fracture measurements were made at 157 stations on 8 islands using scanline, grid mapping and random data collection techniques. Results indicate that fracturing related to the Late Cretaceous to Neogene tectonic history is heterogeneously distributed and can be separated into groups. Four primary groups were identified: deformation bands, bedding-perpendicular fractures, faults and fracture zones, and non-bedding-perpendicular fractures. (Abstract shortened by UMI.).