Dolomite Paleogenesis in the Huron Domain of South Ontario

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The purpose of this project is to further investigate the nature and origin of stratabound, near- horizontally oriented dolomitized beds within Devonian, Silurian, Ordovician carbonates and Cambrian sandstones of the Huron Domain. Constraining timing of fluid flow and chemistry of these fluids and the extent to which these dolomite beds formed in near surface environments as opposed to formation at variable burial depths by hydrothermal and burial processes are fundemental componenet of this investigation. These objectives will be achieved using integrated core, petrographic and geochemical tools. The core facility Library of the Ontario Oil and Gas Repository (OGSR) will be used to provide drilled core samples from within the Huron Domain in addition to cores from Bruce Nuclear Station facility for the purpose of this investigation.Dolomitization occurs when limestone (CaCO3) is progressively changed to dolomite (Ca(MgCO3)2). Dolomitization can occur by a broad range of geologic and geochemical process including: a) sabkha type, b) mixed-water aquifer, c) seepage reflux, d) burial compaction, and e) hydrothermal. These processes lead to a change in formation density that can alter physical properties of the bedrock, including, increased porosity and permeability. In this sense, dolomitization can influence groundwater system evolution through the creation of permeable pathways following lithification and the possibility of localized geologic structure suitable for the accumulation of hydrocarbons.