Michigan Basin

[[Image:Michigan Basin 2.jpg|thumb|Geologic map of the Michigan Basin]] The '''Michigan Basin''' is a [[Structural basin|geologic basin]] centered on the [[Lower Peninsula of Michigan|Lower Peninsula]] of the US state of [[Michigan]]. The feature is represented by a nearly circular pattern of geologic [[Sedimentary rock|sedimentary]] [[Stratum|strata]] in the area with a nearly uniform structural [[Strike and dip|dip]] toward the center of the peninsula. The basin is centered in [[Gladwin County, Michigan|Gladwin County]] where the [[Precambrian]] [[basement rock]]s are {{convert|16000|ft|m}} deep. Around the margins, such as under [[Mackinaw City, Michigan]], the Precambrian surface is around {{convert|4000|ft|m}} down. This {{convert|4000|ft|m|sing=on}} contour on the bedrock clips the northern part of the lower peninsula and continues under [[Lake Michigan]] along the west. It crosses the southern counties of Michigan and continues on to the north beneath [[Lake Huron]]. On the north in the [[Canadian Shield]], which includes the western part of Michigan's [[Upper Peninsula]], Precambrian rocks are exposed at the surface. The eastern margins of [[Wisconsin]] along [[Green Bay (Lake Michigan)|Green Bay]] are along the margins of the basin, while Precambrian rocks crop out to the west in central Wisconsin. The northeastern margin of [[Illinois]] around [[Chicago]] are on the southwestern margin of the basin. The southeast striking [[Kankakee Arch]] continuation of the [[Cincinnati Arch]] forms the southwest boundary of the basin underlying northeastern Illinois and northern [[Indiana]]. To the east, the [[Findlay Arch]] forms the southeast margin of the basin as it strikes to the northeast across northwestern [[Ohio]], under the bed of [[Lake Erie]] and on as the [[Algonquin Arch]] through the southwestern prong of [[Ontario]]. The [[Wisconsin Arch]] forms the western boundary of the basin. The [[Rock (geology)|rocks]] of the basin include [[Cambrian]]-[[Ordovician]] [[sandstone]]s and [[carbonate rock]]s around the margins and at depth. Above or basinward are found the [[Silurian]]-[[Devonian]] [[dolostone]]s and [[limestone]]s with [[Carboniferous]] ([[Mississippian]] and [[Pennsylvanian]]) strata filling the center. A relatively thin veneer of [[Jurassic]] sediments are found in the center of the basin at the surface. The basin appears to have subsided concurrently with basin filling as the sediments within the basin are all relatively shallow water sediments, many of which are richly fossiliferous. The location was located on a geologically passive portion of crust. The development of the basin and the surrounding arches were likely affected by the [[tectonic]] activity of the long term [[Appalachian orogeny]] several hundred miles to the south and east. [[Image:Eastern North American Paleogeograpy Middle Devonian.png|thumb|right|[[Palaeogeography|Paleogeographic]] reconstruction showing the Michigan Basin area during the [[Middle Devonian]] period.]] Within the Precambrian rocks beneath and just west of the center of the basin lies a generally north to northwest trending linear feature that appears to be an ancient [[rift]] in the Earth's [[Crust (geology)|crust]]. This rift appears to be contiguous with the rift zone under [[Lake Superior]]. This, the [[Midcontinent Rift System]], turns west under Lake Superior and then southwest through southern [[Minnesota]], central and western [[Iowa]] and on through southeastern [[Nebraska]] and into eastern [[Kansas]]. ==Natural Resources== The rocks of the Michigan Basin are the source of commercial quantities of [[petroleum]]. The most actively drilled-for source of [[natural gas]] in recent years has been [[shale gas]] from the [[Devonian]] [[Antrim Shale]] in the northern part of the basin. [[Gypsum]] has been mined from rocks in the basin. [[Halite]] (rock salt) occurs in beds of the [[Salina Formation]] ([[Silurian]]) and the [[Detroit River Group]] ([[Devonian]]). The Detroit salt mine has mined rock salt from beneath the [[Detroit metropolitan area]] since 1906. [[Brine]] recovered from wells in the Michigan basin has been used as a commercial source of [[potassium]] salts, [[bromine]], [[iodine]], [[calcium chloride]], and [[magnesium]] salts. ==External links== * [http://strata.geology.wisc.edu/mibasin/ Fossils of the Michigan Basin - University of Michigan] {{coord missing|Michigan}}