PLANT MACROFOSSILS AND PALYNOMORPHS FROM KANAKA CREEK, SOUTHWESTERN BRITISH COLUMBIA: PALEOCENE OR EOCENE?

Sedimentary rocks from the Fraser Lowland of British Columbia range in age from late Cretaceous to Tertiary. The Tertiary (Chuckanut) basin comprises the Chuckanut Formation in Washington State, and the stratigraphically equivalent Huntingdon Formation in the adjacent Fraser Lowland. The Chuckanut has been variously interpreted as latest Cretaceous to Eocene based on biostratigraphy, but fission track ages on zircons suggest a predominantly Eocene age (~55 Ma and younger), although the most basal rocks have not been dated radiometrically. Several palynological studies, however, have suggested that Paleocene rocks are present in the basal Chuckanut.

Plant megafossils consist of carbonaceous compressions and impressions of ferns, conifers, and angiosperm leaves. Two species of Woodwardia ferns are present, and Glyptostrobus and Sequoia- type foliage dominates the conifer assemblage. Many primitive or extinct angiosperms have been recorded, including Platanus, several Macclintockia morphotypes, Macginitiea, Macginicarpa, Corylopsiphyllum-type and others. Particularly significant are identifications of Platanus bella, Viburnum antiquum, Celtis aspera, and two ovulate cones of cf. Fokienia ravenscragensis. The last four taxa are known elsewhere only from Paleocene rocks. Floristic similarities are apparent with other Paleocene localities in western North America, and also with the Paleocene flora of Greenland as described by Koch (1963), suggesting a terrestrial migration corridor between Greenland and North America.

Preliminary palynological investigations record fungi, fern spores, gymnosperm and angiosperm pollen. The palynoflora records a mixed assemblage of Late Paleocene to Eocene palynomorphs. The presence of rare Ilex, Ulmus/Zelkova, Liquidambar, and the spore Trilites solidus suggest an Eocene age, comparable to the younger Kitsilano member of the Huntingdon Formation near Vancouver. A late Paleocene age is indicated by the presence of Paraalnipollenites, Intratriporopollenites, Insulapollenites, and possibly some other types. The presence of index fossils of both ages at this locality suggests the hypothesis that the Kanaka exposures may straddle the Paleocene-Eocene boundary.