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Siderian

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First period of the Paleoproterozoic Era
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Siderian
2500 – 2300 Ma
A reconstruction of the Earth's continents during the middle Siderian, circa 2.4 Ga[citation needed ]
A Siderian banded iron formation in Dales Gorge, Western Australia
Artist's impression of the Earth during the Huronian glaciation, starting from mid-Siderian
Chronology
−2520 —
−2500 —
−2480 —
−2460 —
−2440 —
−2420 —
−2400 —
−2380 —
−2360 —
−2340 —
−2320 —
−2300 —
−2280 —
 
Beginning of Great Oxidation Event
Events of the Siderian Period.
Vertical axis scale: Millions of years ago
Proposed redefinition(s)2630–2420 Ma
Gradstein et al.
Proposed containerNeoarchean
Gradstein et al.
EtymologyName formalityFormalUsage informationCelestial bodyEarth Regional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitPeriod Stratigraphic unitSystem Time span formalityFormalLower boundary definitionDefined ChronometricallyLower GSSA ratified1990[1] Upper boundary definitionDefined ChronometricallyUpper GSSA ratified1990[1]

The Siderian Period (/sˈdɪəri.ən,sɪ-/ ; Ancient Greek: σίδηρος, romanizedsídēros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Ma to 2300 Ma. Instead of being based on stratigraphy, these dates are defined chronometrically.

The deposition of banded iron formations peaked early in this period. These iron-rich formations were formed as anaerobic cyanobacteria produced waste oxygen that combined with iron, forming magnetite (Fe3O4, an iron oxide). This process removed iron from the Earth's oceans, presumably turning greenish seas clear. Eventually, with no remaining iron in the oceans to serve as an oxygen sink, the process allowed the buildup of an oxygen-rich atmosphere. This second, follow-on event is known as the oxygen catastrophe, which some geologists believe triggered the Huronian glaciation.[2] [3]

Since the time period from 2,420 Ma to 2,250 Ma is well-defined by the lower edge of iron-deposition layers, an alternative period named the Oxygenian, based on stratigraphy instead of chronometry, was suggested in 2012 in a geological timescale review.[4]

References

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  1. ^ a b Plumb, Kenneth A. (June 1991). "New Precambrian time scale". Episodes . 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005 . eISSN 2586-1298. ISSN 0705-3797. LCCN 78646808. OCLC 4130038. Open access icon
  2. ^ Kasting, James F.; Ono, Shuehi (2006). "Paleoclimates: The First Two Billion Years". Philosophical Transactions: Biological Sciences. 361 (1470): 917–929. doi:10.1098/rstb.2006.1839. JSTOR 20209693. PMC 1868609 . PMID 16754607.
  3. ^ Kopp, Robert E.; Kirschvink, Joseph L.; Hilburn, Isaac A.; Nash, Cody Z. (2005). "The Paleoproterozoic Snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis" (PDF). PNAS. 102 (32): 11131–11136. doi:10.1073/pnas.0504878102 . PMC 1183582 . PMID 16061801.
  4. ^ Gradstein, F. M.; et al., eds. (2012). The Geologic Time Scale 2012. Vol. 1. Elsevier. pp. 361–365. ISBN 978-0-44-459390-0.

Further reading

[edit ]
Cenozoic Era
(present–66.0 Ma)
Quaternary (present–2.58 Ma)
Neogene (2.58–23.0 Ma)
Paleogene (23.0–66.0 Ma)
Mesozoic Era
(66.0–252 Ma)
Cretaceous (66.0–145 Ma)
Jurassic (145–201 Ma)
Triassic (201–252 Ma)
Paleozoic Era
(252–539 Ma)
Permian (252–299 Ma)
Carboniferous (299–359 Ma)
Devonian (359–419 Ma)
Silurian (419–444 Ma)
Ordovician (444–485 Ma)
Cambrian (485–539 Ma)
Proterozoic Eon
(539 Ma–2.5 Ga)
Neoproterozoic (539 Ma–1 Ga)
Mesoproterozoic (1–1.6 Ga)
Paleoproterozoic (1.6–2.5 Ga)
Archean Eon (2.5–4 Ga)
Hadean Eon (4–4.6 Ga)
 
ka = kiloannum (thousand years ago); Ma = megaannum (million years ago); Ga = gigaannum (billion years ago).
See also: Geologic time scale  • icon Geology portal  • World portal

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