The Sturtian glaciation was a 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 ...
during the
Cryogenian
The Cryogenian (from , meaning "cold" and , romanized: , meaning "birth") is a geologic period that lasted from . It is the second of the three periods of the Neoproterozoic era, preceded by the Tonian and followed by the Ediacaran.
The Cryoge ...
Period when the Earth experienced repeated large-scale glaciations.
, the Sturtian glaciation is thought to have lasted from c. 717
Ma to c. 660 Ma, a time span of approximately 57 million years.
It is hypothesised to have been a
Snowball Earth
The Snowball Earth is a historical geology, geohistorical hypothesis that proposes that during one or more of Earth's greenhouse and icehouse Earth, icehouse climates, the planet's planetary surface, surface became nearly entirely freezing, fr ...
event, or contrastingly multiple regional glaciations, and is the longest and most severe known glacial event preserved in the
geologic record after the much earlier
Huronian glaciation.
Etymology of name
Ultimately, current usage of the term is in reference to the globally significant Sturt Formation (originally Sturtian Tillite) within the
Adelaide Superbasin of Australia. The Sturt Formation is named after
Sturt Gorge,
South Australia
South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...
;
itself named after the
Sturt River, which was given its name in April 1831 by British Military Officer
Captain Collet Barker, after fellow officer and explorer
Charles Sturt
Charles Napier Sturt (28 April 1795 – 16 June 1869) was a British officer and explorer of Australia, and part of the European land exploration of Australia, European exploration of Australia. He led several expeditions into the interior of the ...
.
The Sturtian glaciation is an informal, but commonly used name for the older of two worldwide glacial events (the other is known as the
Marinoan/Elatina glaciation) preserved in Cryogenian rocks.
The term Sturtian was originally defined as a
chronostratigraphic unit (Series) and later proposed as an
international chronostratigraphic division; however, this has been superseded by international nomenclature. The suggestion of the glacial nature of the Sturt Formation during the early 20th century resulted in discussion about Neoproterozoic glaciations (thought to be Cambrian at the time) and encouraged the research that eventually resulted in the Snowball Earth hypothesis.
Geology
Rocks preserving evidence for the Sturtian Glaciation are found on every continent. Notable sections are found in Australia, Canada, China, Ethiopia, Namibia, Siberia, and Svalbard.
According to Eyles and Young, "Glaciogenic rocks figure prominently in the
Neoproterozoic
The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...
stratigraphy
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: lithost ...
of southeastern Australia and the northern
Canadian Cordillera. The Sturtian glaciogenic succession (c. 740
Ma)
unconformably overlies rocks of the Burra Group." The Sturtian succession includes two major
diamictite
Diamictite (; from Ancient Greek (): 'through' and (): 'mixed') is a type of lithified sedimentary rock that consists of nonsorted to poorly sorted terrigenous sediment containing particles that range in size from clay to boulders, suspended ...
-
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
sequences which represent glacial advance and retreat cycles. It is stratigraphically correlated with the Rapitan Group of North America.
in northern Norway may have been deposited during this period.
In 2024 researchers at the University of Adelaide and University of Sydney, using a combination of known geological formations from the Cryogenian Period and plate tectonic modelling, using
EarthByte computer models, proposed the low temperature was the result of low levels of degassing along mid-ocean ridges, the result of the break-up of the supercontinent
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago (Ga) and broke up 750–633 million years ago (Ma). wer ...
.
The duration of the ice sheet advance at the start of the Sturtian glaciation lasted for less than a million years.
Effects on life
In the aftermath of the Sturtian glaciation, biomarkers and body fossils indicate an increase in biological complexity.
See also
*
Adelaide Rift Complex
*
Port Askaig Tillite Formation - a possible correlative in the
Dalradian Supergroup of Ireland and Scotland
Notes
References
{{Ice ages
Ice ages
Cryogenian
1830s neologisms