The Eastern Mid-Continent Region
The Michigan Basin (Fig. 1) is bordered on the west by the Wisconsin Highland and to the north and east of Lake Huron by the Canadian Shield. The Algonquin Arch is a major Precambrian feature trending northeastward in Ontario but becoming almost east-west at the border of Michigan. The northwest Ohio area was a platform during the early part of the Paleozoic, and the Findlay Arch is a post-Silurian structure that developed on this platform. The Findlay Arch plunges northeastward and dies out in the western end of Lake Erie. Contrary to many previously published maps, the Findlay Arch is separated from the Algonquin Arch both in trend and in time of formation. The Kankakee Arch was present by Early Ordovician time as a low-relief feature. Droste and others (1975) have described the detailed geologic history of this area and identified an early to middle Paleozoic feature in the area of the present Kankakee Arch, which they named the Wabash Platform. The Wisconsin Highland is a persistent positive area, which was definitely present by Late Cambrian time.
Areas omitted from this study are Manitoulin Island, the Bruce Peninsula, and southwestern Ontario, which are covered in a separate publication by Stott and Aitken (in preparation). Also omitted is the Door Peninsula of Wisconsin, which because of its isolation from the rest of the Michigan Basin is better related to the strata adjacent to the Wisconsin Highland. Northeastern Illinois is included in the chapter on the Illinois Basin.
In order to avoid
Figures & Tables
Sedimentary Cover—North American Craton
The “sedimentary cover” refers to the stratified rocks of youngest Proterozoic and Phanerozoic age that rest upon the largely crystalline basement rocks of the continental interior. The early chapters of the volume present data and interpretations of the geophysics of the craton and summarize, with sequential maps, the tectonic evolution of the craton. The main body of the text and accompanying plates and figures present the stratigraphy, structural history, and economic geology of specific sedimentary basins (e.g., Appalachian basin) and regions (e.g., Rocky Mountains). The volume concludes with a summary chapter in which the currently popular theories of cratonal tectonics are discussed and the unresolved questions are identified.