Sedimentology and post-glacial history of Lake Manitoba

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dc.contributor.authorLast, William.en_US
dc.date.accessioned2009-12-01T20:15:24Z
dc.date.available2009-12-01T20:15:24Z
dc.date.issued1980en_US
dc.degree.disciplineEarth Sciencesen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractLake Manitoba is a large (4700 km2), shallow (z = 4.0 m), brackish water lake located in south-central Manitoba. Sediment cores up to 13'5 m in length were taken at 50 offshore sites in the main South Basin of the lake. These cores were analyzed at varying intensities for over 40 physical, chemical, and mineralogical sediment parameters. The modern offshore sediments of the South Basin are mainly silts and clayey silts, and are composed of detrital and authigenic carbonates (20-60%), clay minerals (20-50%), organic matter (15-30%), quartz (15-30%), and feldspar (2-10%). Quartz, feldspar, and dolomite are in greatest abundance around the margin of the offshore basin, whereas organic matter, calcite, and clay minerals are concentrated in the central portion of the basin. The authigenic calcite, precipitated in response to high levels of supersaturation brought about by evaporative concentration and extensive phytoplankton productivity during the ice-free season, contains an average of about 7 mole percent MgCO3, in the crystal lattice. The post-glacial sediments in the South Basin of Lake Manitoba are composed dominantly of silty clay and clayey silt except toward the extreme southern end of the basin where less clayey and more sandy sediments are common. The clay content, quartz, feldspar, and dolomite as well as K, Na,Fe,and Mg show a general increase with depth in the sediment cores,' while silt, moisture content, organic matter, calcite, and Ca decrease with depth. On the basis of variations in these and other sediment parameters investigated, six lithostratigraphic units are recognized in the post-glacial record of the lake (Units A, B, C, D, E, and F from bottom to top)...en_US
dc.format.extentxxi, 687 leaves :en_US
dc.format.extent25509658 bytes
dc.format.mimetypeapplication/pdf
dc.identifierocm72785688en_US
dc.identifier.urihttp://hdl.handle.net/1993/3448
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.rightsThe reproduction of this thesis has been made available by authority of the copyright owner solely for the purpose of private study and research, and may only be reproduced and copied as permitted by copyright laws or with express written authorization from the copyright owner.en_US
dc.titleSedimentology and post-glacial history of Lake Manitobaen_US
dc.typedoctoral thesisen_US
local.subject.manitobayesen_US
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