The Black River Group is a

geologic group Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

that covers three sedimentary basins in the Eastern and Midwestern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. These include the

Appalachian Basin The geology of the Appalachians dates back to more than 480 million years ago. A look at rocks exposed in today's Appalachian Mountains reveals elongate belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ...

Illinois Basin The Illinois Basin is a Paleozoic depositional and structural basin in the United States, centered in and underlying most of the state of Illinois, and extending into southwestern Indiana and western Kentucky. The basin is elongate, extending app ...

and the

Michigan Basin 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 towa ...

. It dates back to the Late

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

. It is roughly equivalent to the

Platteville Group There are a few places named Platteville in the United States: * Platteville, Colorado * Platteville, Wisconsin, a city *Platteville (town), Wisconsin Platteville is a town in Grant County, Wisconsin, United States. The population was 1,513 at t ...

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Roc ...

. 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 The Cincinnati Arch is a broad structural uplift between the Illinois Basin to the west, the Michigan Basin to the northwest and the Appalachian Basin and Black Warrior Basin to the east and southeast. It existed as a positive topographic area d ...

& Findley Arch. Large parts of the Black River have been dolomized (where the parent limestone CaCO₃ has been turned into

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

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 Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...

reservoirs.

Description

The Black River Group is characterized by

carbonates A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

, primarily

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

. Some

dolostone Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, thou ...

s can be found in localized areas. Due to fracturing and porosity naturally occurring with in the formation it servers as a gas reservoir throughout its reach. It also serves as an oil reservoir in Michigan and North West Ohio.

Stratigraphy

The Black River Group is predominantly composed of carbonates. In addition clay minerals maybe found in differing amounts. Locally sand and silt maybe found in thin horizons especially in the eastern reaches of the unit. In addition there are K-Bentonite beds. These were formed as a result of

volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are ofte ...

depositing layers of

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

The Black River Group was deposited during a time when large parts of North America were a passive cratonic margin. North America at the time was near the equator and was a tropical environment. Large parts of what is now North America were covered by the

Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoc ...

. The Black River Group was formed during a time of transition time where

Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...

was subject to the beginnings of the

Taconic Orogeny The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the Unit ...

. During the

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ag ...

the Iapetus began to slowly close. As Laurentia moved towards an Island Arch that it would eventually collide with the crust folded downward. As this happened the carbonate deposition of the continental shelf gradually gave way to clastic deposits of a deep marine environment. As a result, there are more siliceous deposits to the east. The Taconic Orogeny occurred to the east and this formed a basin but further west the crust buckled up into an arch. The result was the

. This arch was eroded back to late Ordovician aged rock. This split the basin that the Iapetus Ocean into three separate basins.

Subunits

New York State

Amsterdam Limestone

The Amsterdam Limestone is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

. It dates back to the

. It is a unit of the Black River Group in Eastern New York.

= Fossils

Cartersoceras ''Cartersoceras'' is a genus of nautiloid cephalopods placed in the Orthocerida, Orthocerid family Baltoceratidae, established by Rousseau Flower (1964), for species formally included in part in ''Murrayoceras'', and in part in "''Sacotoceras''". ...

''noveboracense''

Waterton Limestone

The Waterton Limestone is a

. It dates back to the

. It is a unit of the Black River Group in Eastern New York.

Lowville Formation

The Lowville Formation is a

and

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the

Energy production

The Black River Group acts as a reservoir for

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...

and

. The reservoirs are associated with dolostones and. Gas and oil fields can be found in New York, Pennsylvania, Ohio, Indiana, Kentucky, Michigan, and Tennessee.

References

{{Stratigraphic column of West Virginia Ordovician Indiana Ordovician Michigan Ordovician Ohio Ordovician West Virginia