Abstract

The Neogene, marine to terrestrial Skonun Formation of the Queen Charlotte Islands (MacKenzie, 1916; Sutherland Brown, 1968) interfingers with the volcanic Masset Formation (Sutherland Brown, 1968; Hickson, 1988). The Skonun Formation consists of friable rocks and outcrop on the Queen Charlotte Islands is limited. However, Richfield et al.’s six wells on northeastern Graham Island have penetrated siltstones, shales and lignites. Shell wells in the Hecate Strait and Queen Charlotte Sound have penetrated up to 4750 m of predominantly sedimentary rocks, which are at least partly equivalent in age to the Skonun Formation outcrops (Shouldice, 1971). These Tertiary strata are important to petroleum exploration in the Queen Charlotte Basin.

Previous palynostratigraphic data for the Tertiary sediment are based on limited outcrop on Graham Island (Martin and Rouse, 1966), samples from the Cinola gold deposit on central Graham Island (Champigny et al., 1981), cuttings from wells in the Queen Charlotte Sound (Hopkins, 1975, 1981), and sidewall cores from offshore wells (unpublished Shell paleontology reports). The present research more formally identified the palynostratigraphy by quantitative analysis of palynomorphs from core samples from the Tow Hill No. 1 well. This well, located on northeastern Graham Island, penetrates 1830 m of Skonun Formation. Middle Miocene to Late Pliocene ages have been indicated in previous work. While the number of samples available from core is limited, the problem of caving is eliminated. Closely spaced shale or lignite beds were examined separately in order to compare short-term and long-term changes in the palynological record. Short-term changes in vegetation, likely representing edaphic conditions, can be demonstrated and separated from long-term, stratigraphically useful changes. A stratigraphic break, of yet undetermined age, occurs at about 1100 m in the Tow Hill No. 1 well.