Carbonate microbialite formation in a prairie saline lake in Saskatchewan, Canada: paleohydrological and paleoenvironmental implications

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dc.contributor.authorLast, Fawn
dc.contributor.examiningcommitteeFayek, Mostafa (Geological Sciences) Wang, Feiyue (Environment and Geography) Gierlowski-Kordesch, Elizabeth (Ohio University, Geological Sciences)en_US
dc.contributor.supervisorHalden, Norman (Geological Sciences)en_US
dc.date.accessioned2013-05-03T14:41:26Z
dc.date.available2013-05-03T14:41:26Z
dc.date.issued2010-03en_US
dc.date.issued2012-11en_US
dc.date.issued2012-12en_US
dc.degree.disciplineGeological Sciencesen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractManito Lake is a large, perennial, Na-SO4 dominated hypersaline lake located in the northern Great Plains of western Canada. Significant water level decrease over the past several decades has lead to reduction in volume and surface area. Today, the lake is 15% of its mid -20th century volume and 46% of its former area. This decrease in water level has exposed large areas of nearshore microbialites. These organosedimentary structures have various external morphologies, vary in mineralogical composition, and show a variety of internal fabrics from finely laminated to massive and clotted. These features range from small, mm-scale, finely laminated encrustations to large, reef-like structures up to 5 m high and over 500 m long. Although there is relatively little consistent lateral variability in terms of morphology, the structures do vary significantly with elevation in the basin. Petrographic evidence confirms a strong biological involvement in the formation of these structures. Nonetheless, inorganic and trapping mechanisms may also play a role. Dolomite, aragonite, and calcite are the most commonly found minerals in these structures, however, monohydrocalcite, magnesian calcite, hydromagnesite, dypingite, and nesquehonite are also present. The calcite is a pseudomorph after ikaite, which forms an open porous dendritic and shrub-like fabric, comprising the interiors of massive shoreline microbialite mounds and pinnacles. These ikaite pseudomorphs are encased in millimeter to centimeter-scale laminated dolomite-aragonite rinds. Radiocarbon dating and stable isotope analysis have indicated microbialite formation began about 2200 yBP in a shallow, productive, saline and cold lake. Over the next 900 years, the microbialites record a transgressing lake in a cool climate, which corresponds to a period not previously documented in this region but is referred to as the Dark Ages Cold Period, which has been documented in other parts of the Northern Hemisphere. This is followed by 500 years of warmer conditions coinciding with the Medieval Climate Anomaly. Starting about 600 years ago the lake experienced a dramatic decrease in level resulting in formation of extensive carbonate pavements, cemented siliciclastics, rinds, and coatings.en_US
dc.description.noteOctober 2013en_US
dc.identifier.citationLast, F.M, Last, W.M., Halden, N.M. 2010. Carbonate microbialites and hardgrounds from Manito Lake, an alkaline hypersaline lake in the northern Great Plains of Canada. Sedimentary Geology 225: 34-49en_US
dc.identifier.citationLast, F.M., Last, W.M. 2012. Lacustrine carbonates of the northern Great Plains of Canada. Sedimentary Geology 277-278:1-31en_US
dc.identifier.citationLast, F.M, Last, W.M., Halden, N.M. 2012. Modern and late Holocene dolomite formation: Manito Lake, Saskatchewan, Canada. Sedimentary Geology 281: 222-237en_US
dc.identifier.urihttp://hdl.handle.net/1993/19888
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.publisherElsevieren_US
dc.publisherElsevieren_US
dc.rightsopen accessen_US
dc.subjectmicrobialitesen_US
dc.subjectsaline lakeen_US
dc.subjectlacustrine dolomiteen_US
dc.subjectikaiteen_US
dc.subjectnorthern Great Plainsen_US
dc.subjectCanadaen_US
dc.subjectSaskatchewanen_US
dc.subjectpaleolimnologyen_US
dc.subjectgeolimnologyen_US
dc.subjectlimnologyen_US
dc.subjectQuaternary geologyen_US
dc.subjectsedimentologyen_US
dc.subjectcarbonate sedimentologyen_US
dc.titleCarbonate microbialite formation in a prairie saline lake in Saskatchewan, Canada: paleohydrological and paleoenvironmental implicationsen_US
dc.typedoctoral thesisen_US
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