FACIES ARCHITECTURE AND STRATIGRAPHY OF THE PALEOGENE HUNTINGDON FORMATION AT ABBOTSFORD, BRITISH COLUMBIA, CANADA

The Paleogene Huntingdon Formation is a succession of fluvial sandstone, pebble conglomerate and mudstone preserved in southwest British Columbia, Canada. It is correlative with, and continuous in the subsurface to, the Chuckanut Formation in northwest Washington State. The Huntingdon and Chuckanut formations were deposited in the Chuckanut basin during late Paleocene, Eocene, and possibly Oligocence time. This basin is of economic interest because of possible hydrocarbons, coal bed methane and as a storage reservoir for natural gas. The study area includes the proposed type section of the Huntingdon Formation in Abbotsford, British Columbia, Canada.

Fluvial architectural analysis and facies analysis of the type area indicates that the formation formed as a coarse, sand-dominated, terrestrial fluvial system. The range of features suggests proximal to distal transition from alluvial to braided to transitional sand-dominated meandering river systems. Sandstone and pebble conglomerate clasts are dominated by chert types, typical of 1st order basin provenance from nearby Cascade oceanic terrranes to the east.

The Chuckanut Basin has been interpreted as an abnormally large strike-slip basin. However the Huntingdon and Chuckanut formations combined are not anomalously thick for the time range of deposition and suggest a basin size which is uncharacteristically large to be a simple strike slip basin. The Chuckanut basin probably formed as a complex hybrid basin, reflecting the transpressive nature of the plate margin setting in this part of the Cordillera during Paleogene time.