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CLIMATE CHANGES AND EVOLUTION OF NORDIC ECOSYSTEMS OF CANADA
BHIRY, NAJAT Laval University, Quebec, Canada.
Grain size, macrofossil and pollen analyses were used to reconstruct paleoecological and paleoenvironmental conditions of small lakes in northern Quebec, Canada. After the retreat of the Laurentide Ice Sheet around 8000 yr B.P., the area was submerged by the Tyrrell Sea. The transition from marine to lacustrine environment occurred between 6000-5400 yr B.P. Two major periods of water-level fluctuations were inferred from organic and mineral sediments: a high-water level that occurred after 3200 yr B.P. and a low water-level that started before 2200 yr B.P. Our chronological data for the first period are consistent with those from nearby Lac des Pluviers and from other lakes in east-central Canada and in the northeastern United States. During the low water-level period, however, there is no evidence for minor fluctuations, whereas other lakes in northern Quebec and east-central Canada underwent several brief lowerings.
Figure 1. Lake Kachishayoot lacustrine terrace
Figure 2. East (LK99-cp1) and west (LK99-cp2) lacustrine terrace sections
Figure 3. Loss-on-ignition, grain size and macrofossil diagram of core LK99-cr2
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