Siderian
| Siderian | ||||||||||||||||||||
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A Siderian banded iron formation in Dales Gorge, Western Australia | ||||||||||||||||||||
Artist's impression of the Earth during the Huronian glaciation, starting from the mid-Siderian | ||||||||||||||||||||
| Chronology | ||||||||||||||||||||
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| Proposed redefinition(s) | 2630 – 2420 Ma Kranendonk et al., 2012 | |||||||||||||||||||
| Proposed container | Neoarchean Kranendonk et al., 2012 | |||||||||||||||||||
| Etymology | ||||||||||||||||||||
| Name formality | Formal | |||||||||||||||||||
| Usage information | ||||||||||||||||||||
| Celestial body | Earth | |||||||||||||||||||
| Regional usage | Global (ICS) | |||||||||||||||||||
| Time scale(s) used | ICS Time Scale | |||||||||||||||||||
| Definition | ||||||||||||||||||||
| Chronological unit | Period | |||||||||||||||||||
| Stratigraphic unit | System | |||||||||||||||||||
| Time span formality | Formal | |||||||||||||||||||
| Lower boundary definition | Defined chronometrically | |||||||||||||||||||
| Lower GSSA ratified | 1990 | |||||||||||||||||||
| Upper boundary definition | Defined chronometrically | |||||||||||||||||||
| Upper GSSA ratified | 1990 | |||||||||||||||||||
| Atmospheric and climatic data | ||||||||||||||||||||
| Mean atmospheric O2 content | c. 0.014007 vol % (0% of modern) | |||||||||||||||||||
| Mean atmospheric CO2 content | c. 11000 ppm (39 times pre-industrial) | |||||||||||||||||||
The Siderian ( /saɪˈdɪəri.ən, sɪ-/) is the first geologic period in the Paleoproterozoic Era and Proterozoic Eon. It lasted from 2500 to 2300 million years ago (Ma), spanning 200 million years, and is followed by the Rhyacian Period. Instead of being based on stratigraphy, these dates are defined chronometrically.
Most continential activity in this period was met with the breakup of the supercontinent Kenorland. While this event mainly occurred in the craton Laurentia, volcanic intrusions and dike swarms have appeared in plates pertaining to Northwestern Europe, South Africa, and Australia in connection to the rifting. In the ocean, emissions from hydrothermal vents contributed to the production and crystallization of minerals, along with varying concentrations of sulfur and iron. While this sedimentation circulated in the ocean, the amounts deposited on the ocean floor contributed to the development of banded iron formations, along with a diverse range of ores such as pyrite and magnetite.
Cyanobacteria continued to develop their molecular structure, with eukaryotes beginning to appear near the end of the period, and they contributed to the ocean's oxidation. Their presence eventually became the partial cause for the build-up of oxygen in Earth's atmosphere, becoming known as the Great Oxidation Event. This led to a decrease in methane and carbon dioxide, which were two major greenhouse gases at the time, dropping the overall global temperature below 0 °C. As a result of this, the Earth experienced three snowball events which have been collectively known as the Huronian glaciation.