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Palynology of middle and late tertiary sediments from the central interior of British Columbia, Canada

University of British Columbia

Sediments of Mid - to Late Tertiary age from the Fraser River and its tributaries near Quesnel and Prince George in central British Columbia have been investigated for plant microfossils. Three rock units have been studied. The Oligocene rock unit consists of interbedded clay, sand, gravel and lignite, and is exposed along the Fraser River at Alexandria Ferry and at the mouth of Narcosli Creek. This unit is dated by titanothere teeth. The probable Miocene rock unit also consists of interbedded clay, silt, sand, gravel and lignite, and is exposed below Moose Heights, near Quesnel. This unit is dated on the basis of pollen and leaves. The Mio-Pliocene rock unit is diatomite and diatomaceous clays, exposed at the Big Bend of the Fraser River, across from Moose Heights, and along the Nechako River. It appears to underlie radiometrically dated rocks. Palynological studies have revealed a sub-tropical to warm temperate Oligocene flora which includes Quercus, Alnus, Carya, Liquidambar, Ulmus, Juglans, Pterocarya, Taxodium, Glyptostrobus, Engelhardtia, Prosopis, Metasequoia, Osmunda, Psilotum, Ephedra and ? Dorstenia. The probable Miocene assemblage contains Juglans, Taxodium, Glyptostrobus, Metasequoia and Alnus, with larger numbers of Liquidambar, Pterocarya, Ulmus, Castanea, Carya and Quercus than in the Oligocene flora. The Mio-Pliocene paleoflora is distinguished by a predominance of cool temperate taxa, e.g. Pinus, Abies, Picea and Cedrus. From pollen evidence a sub-tropical to warm temperate climate is suggested for the Early Oligocene, with the warm, humid climate probably due in large part to the influence of a warm polar sea. The pollen and leaves from the probable Miocene sediments suggest a more temperate climate with less rainfall, due probably to the cooling during the Tertiary. Pollen recovered from the Mio-Pliocene unit indicates a cool temperate climate and establishment of a predominantly coniferous forest. This is the first Oligocene pollen assemblage studied in the Pacific Northwest and the probable Miocene, and Mio-Pliocene assemblages supplement those of other workers in the area. This thesis also provides information on past climatic history of British Columbia and the Pacific Northwest.

Text

2011-06-17

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http://hdl.handle.net/2429/35544

Botany

University of British Columbia

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