Pennsylvanian fluvial-deltaic depositional systems in central lower Michigan: Sedimentology, stratigraphy, and hydrogeology of the Saginaw Aquifer
Published:January 01, 2013
Niah B.H. Venable, David A. Barnes, David B. Westjohn, Peter J. Voice, 2013. "Pennsylvanian fluvial-deltaic depositional systems in central lower Michigan: Sedimentology, stratigraphy, and hydrogeology of the Saginaw Aquifer", Insights into the Michigan Basin, Robb Gillespie
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This field trip is an excursion to exposures of Pennsylvanian bedrock at Grand Ledge, Michigan, as a backdrop for interdisciplinary examination of the sedimentologic, stratigraphic, and hydrologic research conducted on these important bedrock aquifer units.
The areal extent of Pennsylvanian rocks in the central Lower Peninsula of Michigan is ~28,490 km2. Pleistocene glacial deposits overlie these units throughout the state, but the drift is thin and locally absent along the Grand River Valley, in and around Grand Ledge, Michigan. The geology of the Pennsylvanian deposits is known almost entirely from subsurface research, although sparse outcrops occur near Parma and Jackson in Jackson County and at Grand Ledge in Eaton County. These outcrops, especially the ones at Grand Ledge, constitute the only exposures of coal-bearing strata in Michigan where visitors can see massive sandstone, shale, coal, and associated strata, and fine-grained, chaotic, riverbank-slump facies.
The sections of the field trip will attempt to relate Grand Ledge area deposits to the Pennsylvanian section at the state and regional scale. First, general geologic and stratigraphic relations will be described on the basis of knowledge from the nearby cities of Lansing and Mason, where diamond drill cores and geophysical logs from extensively studied groundwater contamination sites are available. Lithologic and geophysical logs from these sites will be reviewed under the pavilion. Next, lithologic type sections of the Pennsylvanian material in outcrop will be observed and discussed. An example of core from a nearby industrial site will be studied under the pavilion during lunch, and a final trip to outcrop will be made to discuss stratigraphic relationships in an effort to bring into perspective the complexities of Pennsylvanian strata in the Michigan Basin.
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Insights into the Michigan Basin
This guidebook volume is a compilation of field excursions offered at the 47th annual meeting of the North-Central Section of the Geological Society of America, held in Kalamazoo, Michigan, May 2013. These field trips examine a wide range of geological time intervals and topics, from Silurian salt, to Cretaceous cosmic impact, to newly interpreted Mississippian–Pennsylvanian Michigan stratigraphy, to Quaternary glacial landscape formation, sand dune development, and present-day coastal bluff stability/erosion issues. Trips geographically range throughout southern Michigan and northern Indiana from Detroit, Michigan, in the east to the Kentland Quarry in Indiana to the west.
Early depositional events within the Michigan Basin are examined deep underground in the Detroit Salt Mine (trip leaders: W.B. Harrison III and E.Z. Manos [onsite leader]). This salt mine has been in operation for more than 100 years, and extends for miles beneath the city of Detroit.
Kentland Quarry, located in northwest Indiana, is the site of a Cretaceous-aged meteorite impact (trip leader: J.C. Weber). This site allows for surface examination of a similar style impact event that occurred in now buried Ordovician-age (Trenton) rocks located in Cass County, (southwest) Michigan.
Mississippian-aged fluvial deposits have been traditionally classified as the youngest bedrock exposed in Michigan. These rocks crop out in the center of the Michigan Basin near Grand Ledge, Michigan (trip leaders: N.B.H. Venable, D.A. Barnes, D.B. Westjohn, and P.J. Voice). Younger, more recently identified, Pennsylvanian rocks will be the subject of a related core workshop at the Michigan Geological Repository for Research and Education (MGRRE) in Kalamazoo (workshop leaders: S. Towne, W.B. Harrison, and D.B. Westjohn).
The regional, surficial geology of southwest Michigan is highlighted by three field trips. The first trip details the glacial landforms and sedimentary features formed by the differing dynamics of the Michigan and Saginaw lobes of the Laurentide Ice Sheet (trip leaders: A.E. Kehew, A.L. Kozlowski, B.C. Bird, and J.M. Esch). The two other trips follow along the Lake Michigan eastern shoreline and examine development of sand dune complexes (trip leader: E. Hansen) and present-day, coastal bluff stability and erosion issues (trip leaders: R.B. Chase and J.P. Selegean).
- depositional environment
- Eaton County Michigan
- field trips
- ground water
- Michigan Lower Peninsula
- planar bedding structures
- road log
- sedimentary structures
- United States
- water resources
- water use
- Grand Ledge
- Grand River valley
- Saginaw Aquifer