Eoarchean

Eoarchean
Eoarchean
4031 ± 3 – 3600 Ma Pha. Proterozoic Archean Had.
Chronology
−4500 — – — – −4000 — – — – −3500 — – — – −3000 — – — – −2500 — – — – −2000 — – — – −1500 — – — – −1000 — – — – −500 — – — – 0 —	Precambrian Hadean Archean Proterozoic Phaner; ozoic Eoarchean Paleoarchean Mesoarchean Neoarchean Paleoproterozoic Mesoproterozoic Neoproterozoic Paleozoic Mesozoic Cenozoic
	(in millions of years)
Etymology
Name formality	Formal
Alternate spelling(s)	Eoarchaean
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Era
Stratigraphic unit	Erathem
Time span formality	Formal
Lower boundary definition	Ten oldest U-Pb zircon ages
Lower boundary GSSA	Along the Acasta River, Northwest Territories, Canada; 65°10′26″N 115°33′14″W / 65.1738°N 115.5538°W
Lower GSSA ratified	2023
Upper boundary definition	Defined Chronometrically
Upper GSSA ratified	1991[citation needed]

The Eoarchean (IPA: /ˌiːoʊ.ɑːrˈkiːən/ EE-oh-ar-KEE-ən; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record. It spans 431 million years, from the end of the Hadean Eon 4031 Mya to the start of the Paleoarchean Era 3600 Mya. The beginnings of life on Earth have been dated to this era and evidence of archaea and cyanobacteria date to 3500 Mya, comparatively shortly after the Eoarchean. At that time, the atmosphere was without oxygen and the pressure values ranged from 10 to 100 bar (around 10 to 100 times the atmospheric pressure today).^[2]^[3]^[4]

Chronology[edit]

The Eoarchean Era was formerly officially unnamed and informally referred to as the first part of the Early Archean Eon (which is now an obsolete name) alongside the Paleoarchean Era.

The International Commission on Stratigraphy now officially recognizes the Eoarchean Era as the first part of the Archaean Eon, preceded by the Hadean Eon, during which the Earth is believed to have been essentially molten.

The Eoarchaean's lower boundary or starting point of 4.031 Gya (4031 million years ago) is officially recognized by the International Commission on Stratigraphy.^[5]

The name comes from two Greek words: eos (dawn) and archaios (ancient). The first supercontinent candidate Vaalbara appeared around the end of this period at about 3,600 million years ago.

Geology[edit]

The beginning of the Eoarchean is characterized by heavy asteroid bombardment within the Inner Solar System: the Late Heavy Bombardment. The largest Eoarchean rock formation is the Isua Greenstone Belt on the south-west coast of Greenland, which dates from 3.8 billion years. The Acasta Gneiss within the Canadian Shield have been dated to be 4,031 Ma and are therefore the oldest preserved rock formations. In 2008, another rock formation was discovered in the Nuvvuagittuq Greenstone Belt in northern Québec, Canada, which has been dated to be 4,280 million years ago.^[6] These formations are presently under intense investigation.^{[clarification needed]}^[7] Carbonate precipitation (caused by heating of sea water by hydrothermal vents) acted as an important sink regulating the concentration of carbon dioxide in the atmosphere during this era.^[8]

Atmosphere[edit]

3,850 million years old apatite from Greenland shows evidence of Carbon-12 enrichment. This has sparked a debate whether there might have been photosynthetic life before 3.8 billion years.^[9]^{[needs update?]}

Proposed subdivisions[edit]

Eoarchean Era — 4031–3600 Mya
- Acastan Period — 4031–3810 Mya
- Isuan Period — 3810–3600 Mya^[10]

References[edit]

^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 29 October 2023.
^ Mulkidjanian, Armen Y. (August 2009). "On the origin of life in the zinc world: 1. Photosynthesizing, porous edifices built of hydrothermally precipitated zinc sulfide as cradles of life on Earth". Biol. Direct. 4: 26–. doi:10.1186/1745-6150-4-26. PMC 3152778. PMID 19703272.
^ Mulkidjanian, A. Y.; Bychkov, A. Y.; Dibrova, D. V.; Galperin, M. Y.; Koonin, E. V. (2012). "Origin of first cells at terrestrial, anoxic geothermal fields". Proc. Natl. Acad. Sci. USA. 109 (14): E821–30. Bibcode:2012PNAS..109E.821M. doi:10.1073/pnas.1117774109. PMC 3325685. PMID 22331915.
^ Mulkidjanian, A. Y. (2011). "Energetics of the First Life". In Egel, R.; Lankenau, D.-H.; Mulkidjanian, A. Y. (eds.). Origins of Life: The Primal Self-Organization. Heidelberg: Springer Verlag. pp. 3–33. ISBN 978-3-642-21625-1.
^ "International Chronostratigraphic Chart v.2023/09" (PDF). International Commission on Stratigraphy. September 2023. Retrieved October 29, 2023.
^ O'Neil, J.; Carlson, R. W.; Francis, D.; Stevenson, R. K. (2008). "Neodymium-142 Evidence for Hadean Mafic Crust". Science. 321 (5897): 1828–1831. Bibcode:2008Sci...321.1828O. doi:10.1126/science.1161925. PMID 18818357. S2CID 206514655.
^ David, J.; Godin, L.; Stevenson, R. K.; O'Neil, J.; Francis, D. (2009). "U-Pb ages (3.8–2.7 Ga) and Nd isotope data from the newly identified Eoarchean Nuvvuagittuq supracrustal belt, Superior Craton, Canada". Geological Society of America Bulletin. 121 (1–2): 150–163. doi:10.1130/B26369.1.
^ Antonelli, Michael A.; Kendrick, Jillian; Yakymchuk, Chris; Guitreau, Martin; Mittal, Tushar; Moynier, Frédéric (5 May 2021). "Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust". Nature Communications. 12 (1): 1–8. doi:10.1038/s41467-021-22748-2. hdl:20.500.11850/484746.
^ Mojzsis, S. J.; Arrhenius, G.; McKeegan, K. D.; Harrison, T. M.; Nutman, A. P.; Friend, C. R. L. (1996). "Evidence for life on Earth before 3,800 million years ago" (PDF). Nature. 384 (6604): 55–59. Bibcode:1996Natur.384...55M. doi:10.1038/384055a0. hdl:2060/19980037618. PMID 8900275. S2CID 4342620.
^ Van Kranendonk, Martin J. (2012). "16: A Chronostratigraphic Division of the Precambrian: Possibilities and Challenges". In Gradstein, Felix M.; Ogg, James G.; Schmitz, Mark D.; Ogg, Gabi M. (eds.). The geologic time scale 2012 (1st ed.). Amsterdam: Elsevier. pp. 359–365. ISBN 978-0-44-459425-9.

External links[edit]

Media related to Eoarchean at Wikimedia Commons
Taxonconcept.stratigraphy.ne: A short fact sheet on the Eoarchean
Eoarchean (chronostratigraphy scale)

[GSSP_Web-1] "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 29 October 2023.

[2] Mulkidjanian, Armen Y. (August 2009). "On the origin of life in the zinc world: 1. Photosynthesizing, porous edifices built of hydrothermally precipitated zinc sulfide as cradles of life on Earth". Biol. Direct. 4: 26–. doi:10.1186/1745-6150-4-26. PMC 3152778. PMID 19703272.

[3] Mulkidjanian, A. Y.; Bychkov, A. Y.; Dibrova, D. V.; Galperin, M. Y.; Koonin, E. V. (2012). "Origin of first cells at terrestrial, anoxic geothermal fields". Proc. Natl. Acad. Sci. USA. 109 (14): E821–30. Bibcode:2012PNAS..109E.821M. doi:10.1073/pnas.1117774109. PMC 3325685. PMID 22331915.

[4] Mulkidjanian, A. Y. (2011). "Energetics of the First Life". In Egel, R.; Lankenau, D.-H.; Mulkidjanian, A. Y. (eds.). Origins of Life: The Primal Self-Organization. Heidelberg: Springer Verlag. pp. 3–33. ISBN 978-3-642-21625-1.

[ICS2023-5] "International Chronostratigraphic Chart v.2023/09" (PDF). International Commission on Stratigraphy. September 2023. Retrieved October 29, 2023.

[6] O'Neil, J.; Carlson, R. W.; Francis, D.; Stevenson, R. K. (2008). "Neodymium-142 Evidence for Hadean Mafic Crust". Science. 321 (5897): 1828–1831. Bibcode:2008Sci...321.1828O. doi:10.1126/science.1161925. PMID 18818357. S2CID 206514655.

[7] David, J.; Godin, L.; Stevenson, R. K.; O'Neil, J.; Francis, D. (2009). "U-Pb ages (3.8–2.7 Ga) and Nd isotope data from the newly identified Eoarchean Nuvvuagittuq supracrustal belt, Superior Craton, Canada". Geological Society of America Bulletin. 121 (1–2): 150–163. doi:10.1130/B26369.1.

[8] Antonelli, Michael A.; Kendrick, Jillian; Yakymchuk, Chris; Guitreau, Martin; Mittal, Tushar; Moynier, Frédéric (5 May 2021). "Calcium isotope evidence for early Archaean carbonates and subduction of oceanic crust". Nature Communications. 12 (1): 1–8. doi:10.1038/s41467-021-22748-2. hdl:20.500.11850/484746.

[9] Mojzsis, S. J.; Arrhenius, G.; McKeegan, K. D.; Harrison, T. M.; Nutman, A. P.; Friend, C. R. L. (1996). "Evidence for life on Earth before 3,800 million years ago" (PDF). Nature. 384 (6604): 55–59. Bibcode:1996Natur.384...55M. doi:10.1038/384055a0. hdl:2060/19980037618. PMID 8900275. S2CID 4342620.

[VanKranendonk2012-10] Van Kranendonk, Martin J. (2012). "16: A Chronostratigraphic Division of the Precambrian: Possibilities and Challenges". In Gradstein, Felix M.; Ogg, James G.; Schmitz, Mark D.; Ogg, Gabi M. (eds.). The geologic time scale 2012 (1st ed.). Amsterdam: Elsevier. pp. 359–365. ISBN 978-0-44-459425-9.

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