Date of Award

7-2006

Degree Name

Master of Science

Department

Geosciences

Access Setting

Masters Thesis-Open Access

Abstract

The Saginaw Aquifer is an important bedrock aquifer serving the needs of over 400,000 people in the Tri-County area of the Central Lower Peninsula of Michigan. The aquifer is comprised of the Pennsylvanian Grand River and Saginaw Formations. This study focuses on expanding existing knowledge of the general sedimentologic and stratigraphic characteristics of these units using conventional geological methods including core analysis, local log to core correlation, local and regional log to log correlation, and biostratigraphy. Analysis of new core from the study area examines facies and depositional environments given cursory coverage in outcrop studies by past researchers.

Incised valley fill geometries common in the Pennsylvanian deposits of other cratonic basins do not adequately describe the closely interstratified relationships between the Grand River and Saginaw-type deposits. Palynologic results support this finding, suggesting an Atokan age for Grand River and Saginaw units, narrowing the depositional time intervals proposed by other workers. The identification of estuarine deposits, with possible tidal signatures, and paleosol successions may be important in future identification of regionally significant stratal boundaries.

Correlation results at the local scale of the Americhem site describe the geometry of hydrologic units as laterally and vertically variable on the scale of hundreds of feet (tens of meters). Extrapolation of these findings to the regional scale of oil and gas well logs highlights lithologic discontinuities. More high-quality core and closely-spaced geosphysical log data is needed in the study area to adequately describe the regional hydrologic and stratigraphic relationships between the Pennsylvanian bedrock aquifer units and underlying strata.

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