Date of Award
1994
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
Five peat-forming environments were investigated for their organic petrological, mineralogical and geochemical characteristics. Wetlands studied included a salt marsh (Nova Scotia) and four peatlands: a freshwater domed bog (Nova Scotia), a fen (Alberta) and two peat plateau bogs (Northwest Territories). These diverse localities provided the opportunity to assess the influence of natural and anthropogenic factors on peat geochemistry in different depositional environments. Core samples were analyzed using the following methods: organic petrology (maceral analysis and reflectance measurements), low and high temperature ashing, x-ray diffraction, INAA and sulfur analysis, ICP-MS, radiocarbon and cesium dating.;Changes in maceral composition generally correlate with shifts in reflectance, and are useful indicators of the degree of degradation and oxidation in various depositional environments. A downcore decrease of fluorescing and red reflecting huminite macerals shows an increase in the degree of degradation, while an abundance of pyrofusinite in certain intervals is indicative of periods of drought and fire activity. In the salt marsh, oxyfusinite and algae are common.;Br, Cl, I and Se exhibit a strong affinity with the organic fraction and are consequently enriched in peat. Distribution of elements associated with the inorganic fraction on the other hand, can generally be explained in terms of mineral matter distribution.;Peat acts as a sink for air- and waterborne elements. Main factors affecting elemental concentration and distribution are geology of the substratum, proximity to the marine environment, elemental affinity, permafrost, redox changes in the zone of water table fluctuation, tephra incorporation, botanical composition, plant bioaccumulation, degree of degradation of peat, and anthropogenic activity. In particular, a substantial enrichment immediately above the permafrost boundary reflects the influence of permafrost on the mobilization of elements.;Framboidal and anhedral pyrite crystals occurring in association with organic matter are observed in both brackish and freshwater peat-forming systems.;A model was developed in the domed bog, showing that pH, botanical, mineralogical and geochemical composition of peat are related and dependent on the trophic conditions. Furthermore, this model can be useful to help understand characteristics of coal deposits.
Recommended Citation
Chague, Catherine, "Geochemistry And Organic Petrology Of Boreal And Subarctic Peats In Canada" (1994). Digitized Theses. 2431.
https://ir.lib.uwo.ca/digitizedtheses/2431