Revisions to the stratigraphy and biochronology of the Upper Cretaceous Nanaimo Group, British Columbia and Washington State

摘要: The stratigraphy of the Upper Cretaceous Nanaimo Group of the Vancouver Island region is revised on the bases of new fossil and field data. Previously unrecognized turbidite facies of the Haslam Formation are proposed as the new Cowichan Member of the Haslam Formation. This member either overlies or intertongues with the new Haslam Creek Member of the Haslam Formation. The Extension–Protection Formation is subdivided into three formations: the lower Extension Formation, the middle Pender Formation (new name) and the upper Protection Formation.The macrofossil zonal succession can be revised to include a new local-range zone superjacent to the Schmidti Zone and subjacent to the Vancouverense Zone named the Chicoensis Zone, based on the Nanaimo Group occurrences of Baculites chicoensis Trask and Submortoniceras chicoense (Trask). Another new zone is proposed superjacent to the Vancouverense Zone and subjacent to the Suciaensis Zone, named the Paciflcum Zone. This latter zone is based on the local Nanaimo Group ranges of Metaplacenticeras cf. M. pacificum (Smith) and Baculites rex Anderson.