Maquoketa Group

Last updated November 28, 2024

The Maquoketa Group is an assemblage of several geologic formations. It is Upper Ordovician in age and named for the Maquoketa River in Iowa. It exists in Missouri, Wisconsin, Iowa, Illinois, and Indiana.

It is equivalent to the all but the basal formations of the Cincinnati Group in Ohio. Illinois and Indiana are the only states where the Maquoketa is considered a group. In other states it is a formation. The Maquoketa was deposited in a shallow intercontinental sea. Most of the clastic sediments are derived from the Appalachians, which were being raised at the end of the Ordovician. To a lesser degree some of the sediments were derived from the Ozark highlands to the southwest.

Scales Formation

In Illinois, the basal formation is called the Scales Formation and consists mainly of dark brown and gray dolomitic shale. In north central Illinois, the bottom half is dominantly a yellowish gray coarse crystalline dolomite (rock form of the mineral dolomite which is related to calcite). It does not contain many fossils, although large trilobites and large cephalopods are known from Elmer-Lason Quarry. It is typically 75 to 100 feet thick. It is the only formation of the Maquoketa Group that is not exposed in northeastern Illinois.

The type section for the Scales Formation is in Jo Daviess County, Illinois. In Illinois the Formation is divided into two members, the lower Elgin Member (mostly dark gray to brown and black shale with dolomite) and the upper Clermont Member (upper gray pure shale) both with type sections in Fayette County, Iowa. However, in Iowa the Scales, Elgin, and Clermont are all members of the Maquoketa Formation (the Maquoketa is not considered a group in Iowa). Over the years, this has slowly led to the Scales being used in Eastern Iowa for the dark shale and the Elgin used in Western Iowa to refer to the dolomite that grades laterally into the Scales. The difference in terms between Iowa and Illinois has made the present nomenclature all but impractical. There is an active effort to revise the nomenclature. Present studies suggest that the Maquoketa should remain a group and not a formation for practical purposes.^{[ citation needed ]}

Fort Atkinson Formation

Overlying the Scales Formation is the Fort Atkinson Formation, which has been informally called the Middle or Divine Limestone by drillers. The Fort Atkinson is a dominantly a red, gray, and white coarse crystalline dolomite with thin beds of green and gray shale. It contains many invertebrate fossils, such as brachiopods and abundant corals. It ranges from 0 to 60 feet in thickness but is typically 40 to 50 feet thick.

Brainard Formation

Above the Fort Atkinson is the Brainard Formation. The Brainard is generally a greenish gray to gray dolomitic soft to hard shale. It contains abundant fossils near the base. It ranges from 0 to 100 feet thick. The variable thickness is due to an erosional unconformity caused by an ice age at the end of the Ordovician, which lowered global sea level.

Neda Formation

The top and youngest formation is the Neda Formation. It exists in small patchy areas and was extensively eroded at the end of the Ordovician. It exists in large isolated patches in the subsurface in Lake, Cook, Will and Du Page counties in Illinois. In Illinois it crops out only at Kankakee River State Park. It is a reddish purple to brown oolitic shale and is sometimes cemented with iron and dolomite. The oolites are black and made of iron oxides instead of the typical calcareous oolites. They are about 0.5 millimeters in diameter. There are no known fossils. In Illinois, it can be as much as 16 feet thick but it is typically no more than 8 feet thick.

Its origin is still debated. We do know that it was deposited near or on an ancient shore and is a sedimentary rock. However, iron oolites are not being actively deposited anywhere in the world today. It is possible that it was originally deposited as a calcareous oolite and hematite later replaced the calcite. Or it could have been deposited directly as an iron oolite. There is strong evidence for both theories.^{[ citation needed ]}

Economic uses

The Maquoketa has almost no economic use since it is dominantly a weak shale interbedded with thin dolomite, it is not good for track ballast or concrete aggregate and is often stripped and piled as waste in open-pit quarries. The main exception is at the Neda's type section in Wisconsin, where it was once mined for iron ore. In Illinois the Neda is too thin and patchy to be economic. The Brainard is too soft to be used as anything other than fill soil. The Fort Atkinson is used to a limited degree as a decorative stone. The Scales is buried too deep and contains too much dolomite to be used for oil shale.

The unit has been identified as a massive hydrocarbon reservoir. Recently legislation was passed in Illinois allowing horizontal drilling in the shale.^{[ citation needed ]}

The Maquoketa group is also a major aquitard. This means that it is very impermeable, and therefore water only measurably flows through it on geologic time-scales. For this reason, it cannot serve as a source of groundwater.

Although not useful to industry, it does contain rare and diverse fossils, some of which are only known in Illinois such as Tentaculites oswegoensis , a small unclassified fossil named after Oswego, Illinois and found in the basal Brainard.

Related Research Articles

<span class="mw-page-title-main">Permian Basin (North America)</span> Large sedimentary basin in the US

The Permian Basin is a large sedimentary basin in the southwestern part of the United States. It is the highest producing oil field in the United States, producing an average of 4.2 million barrels of crude oil per day in 2019. This sedimentary basin is located in western Texas and southeastern New Mexico.

The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores in western North America. Both marine and terrestrial sediments are represented, including lithified sand dunes from an extinct desert. There are at least 14 known unconformities in the geologic record found in the Grand Canyon.

Fossil Mountain is located in the Teton Range, within the Jedediah Smith Wilderness of Caribou-Targhee National Forest, U.S. state of Wyoming.

Charles Mound is a gentle, 1,235-foot (376 m) high hill located in Scales Mound Township, Jo Daviess County, Illinois, United States. It is 2 miles (3.2 km) northeast of the small town of Scales Mound, and 11 miles (18 km) northeast of Galena. Despite its name, Charles Mound is a naturally occurring, erosional feature and is not to be confused with the intentional mounds created by native cultures. It is the highest natural point in the state and is thus considered a state highpoint. It is the lowest state highpoint in the Midwestern region of the United States.

The Michigan Basin is a geologic basin centered on the Lower Peninsula of the U.S. state of Michigan. The feature is represented by a nearly circular pattern of geologic sedimentary strata in the area with a nearly uniform structural dip toward the center of the peninsula.

<span class="mw-page-title-main">Haynesville Shale</span>

The Haynesville Shale is an informal, popular name for a Jurassic Period rock formation that underlies large parts of southwestern Arkansas, northwest Louisiana, and East Texas. It lies at depths of 10,500 to 13,000 feet below the land’s surface. It is part of a large rock formation which is known by geologists as the Haynesville Formation. The Haynesville Shale underlies an area of about 9,000 square miles and averages about 200 to 300 feet thick. The Haynesville Shale is overlain by sandstone of the Cotton Valley Group and underlain by limestone of the Smackover Formation.

The Platteville Limestone is the Ordovician limestone formation in the sedimentary sequence characteristic of the upper Midwestern United States. It is characterized by its gray color, rough texture, and numerous fossils. Its type locality is Platteville, Wisconsin. It was heavily used in the early decades of the building of Minneapolis–Saint Paul and Faribault, Minnesota.

<span class="mw-page-title-main">Redknife Formation</span>

The Redknife Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin.

The Queenston Formation is a geological formation of Upper Ordovician age, which outcrops in Ontario, Canada and New York, United States. A typical outcrop of the formation is exposed at Bronte Creek just south of the Queen Elizabeth Way. The formation is a part of the Queenston Delta clastic wedge, formed as an erosional response to the Taconic Orogeny. Lithologically, the formation is dominated by red and grey shales with thin siltstone, limestone and sandstone interlayers. As materials, comprising the clastic wedge, become coarser in close proximity to the Taconic source rocks, siltstone and sandstone layers are predominant in New York.

The Munising Group or Formation is a 1,700 feet (520 m) thick, white to light grey Cambrian sedimentary unit that crops out in Michigan and Ontario. At one end of its extent, it comprises a basal conglomerate overlain by the Chapel Rock Member and the Miners Castle Member; elsewhere, it comprises the Eau Claire, Galesville (=Dresbach), and Franconia Members. Anhydritic evaporite deposits are present in places. The conglomerate was deposited by rivers in flood, with the Chapel Rock member, which contains deltaic deposits, representing transgression as the conglomerate cones became submerged; the Miners Castle member was deposited further from the shoreline, representing shelf deposits. Its uppermost strata may be Early Ordovician in age, and contain conodonts, trilobites and phosphatic moulds of brachiopods, ostrocoderm fish and gastropods.

The Tomstown Dolomite or Tomstown Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating to the Cambrian Period.

The geology of South Dakota began to form more than 2.5 billion years ago in the Archean eon of the Precambrian. Igneous crystalline basement rock continued to emplace through the Proterozoic, interspersed with sediments and volcanic materials. Large limestone and shale deposits formed during the Paleozoic, during prevalent shallow marine conditions, followed by red beds during terrestrial conditions in the Triassic. The Western Interior Seaway flooded the region, creating vast shale, chalk and coal beds in the Cretaceous as the Laramide orogeny began to form the Rocky Mountains. The Black Hills were uplifted in the early Cenozoic, followed by long-running periods of erosion, sediment deposition and volcanic ash fall, forming the Badlands and storing marine and mammal fossils. Much of the state's landscape was reworked during several phases of glaciation in the Pleistocene. South Dakota has extensive mineral resources in the Black Hills and some oil and gas extraction in the Williston Basin. The Homestake Mine, active until 2002, was a major gold mine that reached up to 8000 feet underground and is now used for dark matter and neutrino research.

The geology of Missouri includes deep Precambrian basement rocks formed within the last two billion years and overlain by thick sequences of marine sedimentary rocks, interspersed with igneous rocks by periods of volcanic activity. Missouri is a leading producer of lead from minerals formed in Paleozoic dolomite.

The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.

The geology of Wisconsin includes Precambrian crystalline basement rock over three billion years old. A widespread marine environment during the Paleozoic flooded the region, depositing sedimentary rocks which cover most of the center and south of the state.

Geology of Latvia includes an ancient Archean and Proterozoic crystalline basement overlain with Neoproterozoic volcanic rocks and numerous sedimentary rock sequences from the Paleozoic, some from the Mesozoic and many from the recent Quaternary past. Latvia is a country in the Baltic region of Northern Europe.

The geology of the United Arab Emirates includes very thick Paleozoic, Mesozoic and Cenozoic marine and continental sedimentary rocks overlying deeply buried Precambrian. The region has extensive oil and gas resources and was deformed during the last several million years by more distant tectonic events.

<span class="mw-page-title-main">Eldon Formation</span> Geologic formation in Canada

The Eldon Formation is a stratigraphic unit that is present on the western edge of the Western Canada Sedimentary Basin in the southern Canadian Rockies of southwestern Alberta and southeastern British Columbia. It is a thick sequence of massive, cliff-forming limestones and dolomites that was named for Eldon Switch on the Canadian Pacific Railway near Castle Mountain in Banff National Park by Charles Doolittle Walcott, who discovered the Burgess Shale fossils. The Eldon Formation was deposited during Middle Cambrian time, and it includes fossil stromatolites. The Eldon forms the scenic cliffs at the top of Castle Mountain, and can also be seen at Mount Yamnuska and other mountains in Banff and Yoho National Parks.

The Knox Supergroup, also known as the Knox Group and the Knox Formation, is a widespread geologic group in the Southeastern United States. The age is from the Late Cambrian to the Early Ordovician. Predominantly, it is composed of carbonates, chiefly dolomite, with some limestone. There are also cherty inclusions as well as thin beds of sandstone.

The Hunton Megagroup also Hunton Super Group, Hunton Group, Hunton Formation and Hunton Limestone is predominantly composed of carbonate rock, deposited between the Silurian and early to mid Devonian periods. In many States it acts as a reservoir for both hydrocarbons and water.

References

1975, H.B. Willman & T.C. Buschbach, Handbook of Illinois Stratigraphy

1983, D.R. Kolata & A.M. Graese, Facies analysis of the Ordovician Maquoketa Group and adjacent strata in Kane County, Northeastern Illinois

1991, A.M. Graese, Facies analysis of the Ordovician Maquoketa Group and adjacent strata in Kane County, Northeastern Illinois

2007, S.D.J. Baumann, Unclassified, Unusual, or Problematic Fossils in Northeastern Illinois

2007, S.D.J. Baumann & T. Arrospide, Paleozoic Geology of the Fox River from Batavia to Oswego Illinois

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.