CGRG Bibliography of Canadian Geomorphology
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Author : Clet, M.; Occhietti, S.; and Richard, P.J.H.
Date : 1991
Title : Palynology and lithostratigraphy at the Pleistocene Donnacona site, St. Lawrence Valley, Quebec
Publication : Geographie physique et Quaternaire
Issue : 45(2):
Page(s) : 125-140
Abstract
Palynology and lithostratigraphy at the Pleistocene Donnacona site, St. Lawrence Valley, Quebec. At Donnacona, a sequence of non-glacial sediments is intercalated between a lower glacial complex and the Gentilly Till. The lower complex consists of a basal till, ice margin deposits, a diamicton, some varves, a till and an upper rudite. The intermediate stratified sequence includes three units: silt and sand with plant debris, dated at > 35,000 BP (UQ-678), stratified coarse sands and a massive silt. The paleoenvironments are assessed from the pollen spectra and concentrations, the taxonomic diversity and the sedimentology. The pollen diagram is divided into four palynozones by statistical treatment. Pollen study demonstrates that the intermediate stratified deposits at Donnacona are younger than the St. Pierre Sediments, except a thin lower zone (palynozone Donnacona 1 with dominant Picea and Abies) which is correlated with the upper part of the St. Pierre Sediments. The remainder of the unit with plant debris is correlated with the Saint-Maurice Rhythmites. Pollen analysis revealed that this unit contains seasonal rhythmites. The pollen content (palynozone Donnacona 2) indicates that a southern Abies forest, which included thermophilous species such as Tsuga and Tilia, was gradually replaced by a Picea forest. The coarse sand unit contains the Donnacona 3 and the lower part of Donnacona 4 palynozones. It is related to the Vieilles-Forges Sands and to a climatic deterioration. The unit below Gentilly Till was deposited in a glacial lake coeval with a forest tundra and later with a tundra (upper part of palynozone Donnacona 4).
Bibliography of Canadian Geomorphology