Cap carbonate
Encyclopedia
Cap carbonates are layers of distinctively textured carbonate
rock
s which typically form the uppermost layer of sedimentary sequences reflecting major glaciations in the geological record.
The rising temperatures, and increased oceanic surface area - due to reduced ice cover and rising sea levels - at the end of a glaciation increase the rate of precipitation
.
High concentrations of greenhouse gas
ses such as carbon dioxide
(CO2) must build up in the atmosphere to overcome the effect of the high reflectivity (albedo
) of ice and allow temperatures to rise sufficiently to begin melting.
Increased precipitation dissolves carbon dioxide from the atmosphere, falling as a weak carbonic acid
- acid rain
.
This would weather exposed silicate
and carbonate rock, including readily-attacked glacial debris, which would releasing large amounts of calcium. When washed into the ocean, these precipitate
to form distinctively textured layers of carbonate sedimentary rock
.
A heavily debated cap carbonate appears at the top of the Gaskiers Glaciation, believed by many to be global in extent
.
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Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
rock
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
s which typically form the uppermost layer of sedimentary sequences reflecting major glaciations in the geological record.
The rising temperatures, and increased oceanic surface area - due to reduced ice cover and rising sea levels - at the end of a glaciation increase the rate of precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
.
High concentrations of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
ses such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
(CO2) must build up in the atmosphere to overcome the effect of the high reflectivity (albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
) of ice and allow temperatures to rise sufficiently to begin melting.
Increased precipitation dissolves carbon dioxide from the atmosphere, falling as a weak carbonic acid
Carbonic acid
Carbonic acid is the inorganic compound with the formula H2CO3 . It is also a name sometimes given to solutions of carbon dioxide in water, because such solutions contain small amounts of H2CO3. Carbonic acid forms two kinds of salts, the carbonates and the bicarbonates...
- acid rain
Acid rain
Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...
.
This would weather exposed silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
and carbonate rock, including readily-attacked glacial debris, which would releasing large amounts of calcium. When washed into the ocean, these precipitate
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
to form distinctively textured layers of carbonate sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
.
A heavily debated cap carbonate appears at the top of the Gaskiers Glaciation, believed by many to be global in extent
Snowball Earth
The Snowball Earth hypothesis posits that the Earth's surface became entirely or nearly entirely frozen at least once, some time earlier than 650 Ma . Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical...
.
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