The Marinoan glaciation, sometimes also known as the Varanger glaciation, was a period of worldwide

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...

that lasted from approximately 650 to 632.3 ± 5.9 Ma (million years ago) during the Cryogenian

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 ...

. This glaciation possibly covered the entire planet, in an event called the Snowball Earth. The end of the glaciation was caused by volcanic release of

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

and dissolution of

gas hydrates Clathrate hydrates, or gas hydrates, clathrates, hydrates, etc., are crystalline water-based solids physically resembling ice, in which small non-polar molecules (typically gases) or polar molecules with large hydrophobic moieties are trapped i ...

and might have been hastened by the release of

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

from equatorial permafrost.

Origin of name and history of terminology

The name is derived from the

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

terminology of the Adelaide Geosyncline (Adelaide Rift Complex) in

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

and is taken from the

Adelaide Adelaide ( ) is the capital city of South Australia, the state's largest city and the fifth-most populous city in Australia. "Adelaide" may refer to either Greater Adelaide (including the Adelaide Hills) or the Adelaide city centre. The dem ...

suburb of Marino. The term Marinoan Series was first used in a 1950 paper by

Douglas Mawson Sir Douglas Mawson OBE FRS FAA (5 May 1882 – 14 October 1958) was an Australian geologist, Antarctic explorer, and academic. Along with Roald Amundsen, Robert Falcon Scott, and Sir Ernest Shackleton, he was a key expedition leader duri ...

and

Reg Sprigg Reginald Claude Sprigg, (1 March 1919 – 2 December 1994) was an Australian geologist and conservationist. At 17 he became the youngest Fellow of the Royal Society of South Australia. During 1946, in the Ediacara Hills, South Australia he di ...

to subdivide the

Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is prec ...

rocks of the Adelaide area and encompassed all strata from the top of the Brighton Limestone to the base of the Cambrian. The corresponding time period, referred to as the Marinoan Epoch, spanned from the middle Cryogenian to the top of the Ediacaran in modern terminology. Mawson recognised a glacial episode within the Marinoan Epoch which he referred to as the Elatina glaciation after the 'Elatina Tillite' (now Elatina Formation) where he found the evidence. However, the term Marinoan glaciation came into common usage because it was the glaciation that occurred during the Marinoan Epoch, as distinct from the earlier glaciation during the Sturtian Epoch (the time period of deposition of the older Sturtian Series). The term Marinoan glaciation was later applied globally to any glaciogenic formations assumed (directly or indirectly) to correlate with Mawson's original Elatina glaciation in South Australia. Recently, there has been a move to return to the term Elatina glaciation in South Australia because of uncertainties regarding global correlation and because an Ediacaran glacial episode (Gaskiers) also occurs within the wide-ranging Marinoan Epoch.

Cryogenian Snowball Earth

Emerging evidence suggests that the Earth underwent a number of glaciations during the Neoproterozoic

era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. Comp ...

. There were three (or possibly four) significant ice ages during the late Neoproterozoic. These periods of nearly complete glaciation of Earth are often referred to as "Snowball Earth", where it is hypothesized that at times the planet was covered by ice thick. Of these glaciations, the

Sturtian glaciation The Sturtian glaciation was a Snowball Earth glaciation, or perhaps multiple glaciations, during the Cryogenian Period when the Earth experienced repeated large-scale glaciations. The duration of the Sturtian glaciation has been variously defined, ...

was the most significant, whereas the Marinoan was a shorter, but still worldwide glaciation. Other Cryogenian glaciations were probably small and not global as compared to the Marinoan or Sturtian glaciations. During the Marinoan glaciation, characteristic glacial deposits indicate that

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

suffered one of the most severe ice ages in its history.

Glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

s extended and contracted in a series of rhythmic pulses, possibly reaching as far as the equator. The melting of the Snowball Earth is associated with greenhouse warming due to the accumulation of high levels of carbon dioxide in the atmosphere.

Evidence

Even though much evidence has been lost through geological changes, field investigations show evidence of the Marinoan glaciation in China, Svalbard archipelago and South Australia. In

Guizhou Province Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to ...

, China, glacial rocks were found to be underlying and overlying a layer 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 ...

es which contained

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

minerals, which could be dated through

radioisotopes A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

. Glacial deposits in South Australia are approximately the same age (about 630 Ma), confirmed by similar stable

carbon isotope Carbon (6C) has 15 known isotopes, from to , of which and are stable. The longest-lived radioisotope is , with a half-life of years. This is also the only carbon radioisotope found in nature—trace quantities are formed cosmogenically by t ...

s, mineral deposits (including sedimentary barite), and other unusual sedimentary structures. Two diamictite-rich layers in the top of the Neoproterozoic strata of the northeastern Svalbard archipelago represent the first and final phases of the Marinoan glaciation. According to Eyles and Young, the Marinoan is a second episode of

glaciation (680–690 Ma) occurring in the Adelaide Geosyncline. According to them, "It is separated from the Sturtian by a thick succession of sedimentary rocks containing no evidence of glaciation. This glacial phase could correspond to the recently described Ice Brooke formation in the northern

Cordillera A cordillera is an extensive chain and/or network system of mountain ranges, such as those in the west coast of the Americas. The term is borrowed from Spanish, where the word comes from , a diminutive of ('rope'). The term is most commonly u ...

References

{{Greenhouse and Icehouse Earth Ice ages Cryogenian Glaciology Extinction events

Origin of name and history of terminology

Cryogenian Snowball Earth

Evidence

See also

References