Knox Supergroup | |
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Stratigraphic range: Late Cambrian-Dapingian ~ | |
![]() Sphalerite from the Knox Superroup, Tennessee | |
Type | Supergroup |
Unit of | Sauk |
Sub-units |
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Underlies | Ancel Group, Wells Creek Dolomite |
Overlies | |
Lithology | |
Primary | Dolomite |
Other | Limestone and sandstone |
Location | |
Region | Indiana, Illinois, Kentucky, New York, Ohio, Pennsylvania, West Virginia |
Country | United States |
Type section | |
Named for | Knox County, Tennessee |
Named by | Safford (1869, p. 151) |
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. [1] [2]
The Knox lies beneath a unconformity known as the Knox Unconformity. There is well-developed karst topography at the top of the Knox Supergroup. This demonstrates a prolonged period of erosion. This has modern economic impact because of forming reservoirs for hydrocarbons as well as some mineral deposits. [2]
The Everton Formation is a geologic formation in northern Arkansas through Missouri, Illinois and Indiana that dates to the middle Ordovician Period. [3] It was named by Ulrich (1907) for exposures found around Everton, Arkansas. Fossils of Conodonts Paraprioniodus costatus and Leptochirognathus quadratus indicate Whiterockian age. [4] Unconformities separate this formation from the underlying Powell Formation and the overlying St. Peter Sandstone Formation. The Everton Formation is composed primarily of dolomite, limestone, and some sandstone as well as a zone of breccia. There are local thick sections of a friable sandstone. The grains are nearly identical to the overlying St. Peter Sandstone, and may cause some confusion in identifying the different formations. The sand grains are medium grained, well rounded and are frosted. Fossils of ostracods, cephalopods, gastropods, bivalves, trilobites, and bryozoans are preserved within the formation. [5]
Five named members of the Everton Formation are recognized (in stratigraphic order):
The Beekmantown Group is the upper unit of the Knox Supergroup. [6] It is a late Cambrian to lower–middle Ordovician geologic group that occurs in the eastern Canada (Québec) and northeastern United States, [7] datable from its conodont fauna. It contains dolomitic sandstones and carbonates from just off land from the palaeocoastline. Most likely the Arbuckle Arbuckle Group of Oklahoma, and Ellenburger Group of Texas are equlivant to the Beekmantown. [8]
The usage of the term is diverse and depends on the state or region in question, and the group encompasses different formations in different regions. In some states it is considered a formation rather than a group, but the lithology varies by region. [9]
In Pennsylvania the Beekmantown is broken down into the Bellefonte Formation at the Knox Unconformity, followed by the either the Axemann Formation or the Nittany Dolomite, with the Stonehenge Dolomite at its base. The Stonehenge is stratigraphically equitant to the Chepultepec Formation. [6]
Zinc is mined in outcrops found in Virginia. Mostly in Augusta, Rockingham, and Shenandoah counties. The largest is the Bowers-Campbell Mine. [10]
Within the breccia zone galena is extracted along with small amounts of sphalerite and pyrite. [8]
The Beekmantown is quarried in many locations for aggregate and rock. [11]
The Chepultepec Formation is an Early Ordovician-aged geological formation in the Appalachian regions of Eastern North America. Also known as the Chepultepec Dolomite, it is a unit of the Upper Knox Group, overlying the Copper Ridge Dolomite and underlying the Longview-Kingsport-Mascot sequence. The formation was named by E. O. Ulrich in 1911 for the town of Chepultepec (now Allgood). [6]
The Chepultepec Formation is a primarily limestone and dolomite formation, the earliest formation of the Ordovician period in its area. Further north, it is equivalent to the Stonehenge Formation of the Beekmantown Group. [12] The formation was first described from Allgood, and has also been found in Tennessee and Virginia. [13] In Virginia, the Chepultepec Formation has a habit of forming large natural arches, including Natural Tunnel in Scott County and Natural Bridge in Rockbridge County. [14] [15]
This group includes the Oneota Formation and the Shakopee Formation.
The Oneota Formation is a geologic formation in the upper Midwest (United States) including Minnesota, Illinois, Indiana and Wisconsin. It preserves marine fossils dating back to the Ordovician period. [16]
The Oneota Formation is a geologic formation in the upper Midwest (United States) including Minnesota, Illinois, Indiana and Wisconsin. It preserves marine fossils dating back to the Ordovician period. [16]
The Sugar Loaf landmark located in Winona, Minnesota is made of Oneota Dolomite.
The Shakopee Formation is a geologic formation in Illinois, Indiana, Wisconsin, and Minnesota. It preserves fossils dating back to the Ordovician period. It is named after the town of Shakopee, Minnesota, where the formation can be seen in bluffs along the Minnesota River.
The formation is broken up into two members, the New Richmond and Willow River Members. The Shakopee was deposited in a peritidal setting and is divided by an unconformity. The unconformity left river valleys that were filled with siliciclastic material that was covered by marine deposits. Facies-defining cycles are divided into grainy carbonate, muddy carbonate, sandstone, shale, and Stromatolitic–Algal mat Boundstones. [17]
Stromatolite reefs are a common occurrence in the Shakopee and are well documented throughout. Some of the recognized species of stromatolites are cryptozoon minnesotense, cryptozoon liberta and cryptozoon rosemontensis. [18]
The Kaibab Limestone is a resistant cliff-forming, Permian geologic formation that crops out across the U.S. states of northern Arizona, southern Utah, east central Nevada and southeast California. It is also known as the Kaibab Formation in Arizona, Nevada, and Utah. The Kaibab Limestone forms the rim of the Grand Canyon. In the Big Maria Mountains, California, the Kaibab Limestone is highly metamorphosed and known as the Kaibab Marble.
The geology of Illinois includes extensive deposits of marine sedimentary rocks from the Palaeozoic, as well as relatively minor contributions from the Mesozoic and Cenozoic. Ice age glaciation left a wealth of glacial topographic features throughout the state.
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.
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.
The Ordovician Bellefonte Formation is a mapped bedrock unit in central Pennsylvania. It is the uppermost unit of the Beekmantown Group. The top of the Bellefonte is marked by the Knox Unconformity.
The Ordovician Kittatinny Formation or Kittatinny Limestone is a dolomitic limestone formation in New Jersey. The Kittatinny Limestones are located primarily in the Kittatinny Valley where it lies above the Ordovician Martinsburg Formation within the long valley running from Picatinny Arsenal in Rockaway Township, southwest toward Chester Township. It overlies the Cambrian Hardyston Quartzite.
Except where underlain by the Sixtymile Formation, the Tapeats Sandstone is the Cambrian geologic formation that is the basal geologic unit of the Tonto Group. Typically, it is also the basal geologic formation of the Phanerozoic strata exposed in the Grand Canyon, Arizona, and parts of northern Arizona, central Arizona, southeast California, southern Nevada, and southeast Utah. The Tapeats Sandstone is about 70 m (230 ft) thick, at its maximum. The lower and middle sandstone beds of the Tapeats Sandstone are well-cemented, resistant to erosion, and form brownish, vertical cliffs that rise above the underlying Precambrian strata outcropping within Granite Gorge. They form the edge of the Tonto Platform. The upper beds of the Tapeats Sandstone form the surface of the Tonto Platform. The overlying soft shales and siltstones of the Bright Angel Shale underlie drab-greenish slopes that rise from the Tonto Platform to cliffs formed by limestones of the Muav Limestone and dolomites of the Frenchman Mountain Dolostone.
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 Neoproterozoic Chuar Group consists of 1,600 m (5,200 ft) of exceptionally well-preserved, unmetamorphosed sedimentary strata that is composed of about 85% mudrock. The Group is the approximate upper half of the Grand Canyon Supergroup, overlain by the thin, in comparison, Sixtymile Formation, the top member of the multi-membered Grand Canyon Supergroup. The outcrop of the Chuar Group strata is limited to exposures along the western bank of the Colorado River in a 150 km2 (58 sq mi) area of the eastern Grand Canyon, Arizona. The strata of the Chuar Group have been subdivided into the Galeros Formation (lower) and the Kwagunt Formation (upper) using the base of the prominent, thick sandstone unit.
The Jordan Formation is a siliciclastic sedimentary rock unit identified in Illinois, Michigan, Wisconsin, Minnesota, and Iowa. Named for distinctive outcrops in the Minnesota River Valley near the town of Jordan, it extends throughout the Iowa Shelf and eastward over the Wisconsin Arch and Lincoln anticline into the Michigan Basin.
The Black River Group is a geologic group that covers three sedimentary basins in the Eastern and Midwestern United States. These include the Appalachian Basin, Illinois Basin and the Michigan Basin. It dates back to the Late Ordovician period. It is roughly equivalent to the Platteville Group in Illinois. In Kentucky and Tennessee it is also known as the High Bridge Group. In areas where this Geologic Unit thins it is also called the Black River Formation (undifferentiated). One example of this is over the Cincinnati Arch & Findley Arch. Large parts of the Black River have been dolomized (where the parent limestone CaCO3 has been turned into dolomite CaMg(CO3)2.) This happed when there was interaction of hot saline brine and the limestone. This created hydrothermal dolomites that in some areas serve as petroleum reservoirs.
The Montoya Group is a group of geologic formations in westernmost Texas and southern New Mexico. It preserves fossils dating back to the late Ordovician period.
The Mansfield Natural Gas Field is located west of Mansfield, Ohio, within the Appalachian foreland basin. The field is 1.5 miles (2.4 km) long by 1.4 miles (2.3 km) wide and is in a general oval shape, stretching northward. This field, although small, is an analog for many of the natural gas fields that occur within the Appalachian Basin. It was first discovered by the Pan American Petroleum and Transport Company in the early 1930s. It is part of the Utica – Lower Paleozoic system, which is estimated to make up 15 to 20 percent of the total hydrocarbon abundance of the Appalachian Basin.
Lahaska Creek is a tributary of Mill Creek in Wrightstown Township, Bucks County, Pennsylvania. The Geographic Name Information System I.D. is 1178763, U.S. Department of the Interior Geological Survey I.D. is 02632.
The geology of Ohio formed beginning more than one billion years ago in the Proterozoic eon of the Precambrian. The igneous and metamorphic crystalline basement rock is poorly understood except through deep boreholes and does not outcrop at the surface. The basement rock is divided between the Grenville Province and Superior Province. When the Grenville Province crust collided with Proto-North America, it launched the Grenville orogeny, a major mountain building event. The Grenville mountains eroded, filling in rift basins and Ohio was flooded and periodically exposed as dry land throughout the Paleozoic. In addition to marine carbonates such as limestone and dolomite, large deposits of shale and sandstone formed as subsequent mountain building events such as the Taconic orogeny and Acadian orogeny led to additional sediment deposition. Ohio transitioned to dryland conditions in the Pennsylvanian, forming large coal swamps and the region has been dryland ever since. Until the Pleistocene glaciations erased these features, the landscape was cut with deep stream valleys, which scoured away hundreds of meters of rock leaving little trace of geologic history in the Mesozoic and Cenozoic.
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.
The Douglas Lake Member is a geologic unit of member rank of the Lenoir Limestone that overlies the Mascot Dolomite and underlies typical nodular member of the Lenoir Limestone in Douglas Lake, Tennessee, region. It fills depressions that are part of a regional unconformity at the base of Middle Ordovician strata, locally the Lenoir Limestone, that separates them from the underlying Lower Ordovician strata, locally the Knox Group.
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.