The significance of pollen-rich inorganic lake sediments in the Cratére du Nouveau-Quèbec area, Ungava, Canada |
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| Authors: | PIERRE J H RICHARD MICHEL A BOUCHARD PIERRE GANGLOFF |
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| Institution: | Départment de Géographie and Michel A. Bouchard, Département de Géologie, Universitéde Montréal, C.P. 6128, Succ. "A" Montrél, Canada H3C 317;2nd August, 1990 |
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| Abstract: | Unexpectedly high pollen concentrations characterize the basal, silty part of the postglacial sediments accumulated in two lakes from the Cratère du Nouveau-Quebéc area, Ungava. These lacustrine silts and their pollen content result from early postglacial washing of a pollen bearing till. The till must therefore ahve incorporated pollen that relates to events prior to the last glacial event. The matrix of the till deposits surrounding the lakes shows outstandingly high pollen concentrations. It is hypothesized that because of the proximity of the ice divide during the last (and earlier) ice advance(s) in Ungava, the previously depoisited till and the pollen that haad accumulated in its matrix during the interglacial interval(s) were preserved in relict till plains or recycled into the till of teh last glaciation. The crater's age has been established at 1.4 Ma and holds a minimum thickness of 95 m of sediments. It is very likely filled with successive tills or related glacigenic deposits perhaps representing the whole length of time since the crater was formed. Alike the most recent till, these deposits should pollen. there is thus the prospect ofr a 1.4 Ma old pollen record for Ungava. |
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