CGRG Bibliography of Canadian Geomorphology
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Author : Dean, J.M.
Date : 2000.
Title : High resolution palaeoceanography and palaeoclimatology from Late Holocene laminated sediments, Saanich Inlet, British Columbia.
Publication : Unpublished Ph.D. dissertation. Southampton.
Issue :
Page(s) :
Abstract
Late Holocene (c. 2100 yr BP) varved sediments recovered from Saanich Inlet, Ocean Drilling Program Leg 169S, have been analyzed using high resolution scanning electron microscope techniques. The individual centimetre-scale varves comprise two segments: a biogenic varve-segment which consists of up to 19 alternating diatom ooze and diatomaceous mud laminae, which were deposited during spring through autumn; and a terrigenous varve-segment containing up to 6 laminae dominated by silty clay, which were deposited during winter. The laminae within the varves record individual flux events of a few weeks to months duration. Diatom flux typically reached the fjord floor as a mixture of whole/fragmented aggregates and zooplankton faecal pellets. The diatom succession within the biogenic varve-segment typically comprises: an early spring Thalassiosira spp. bloom, followed by a late spring Chaetoceros spp. dominated bloom, a late spring/early summer Skeletonema costatum bloom and a series of one to several summer/autumn Chaetoceros spp. -dominated blooms. Inter-annual variability in diatom sediment flux is typically recorded by the presence/absence of Thalassiosira spp., S costatum and the number of summer/autumn Chaetoceros spp. - dominated blooms. The varved sediment documents a major increase in the sedimentation rate at approximately 2100 varve yr BP. This represents a transition from a colder/drier climate during the Tiedmann glacial advance when sediment flux was lower, to a relatively warmer/wetter late Holocene climate when sediment flux increased. As glaciers receded, fluvial input increased throughout the year as a result of increased rainfall during winter months and glacial meltwater during spring through autumn months.
Bibliography of Canadian Geomorphology