The Eoarchean (/ˌiːoʊ.ɑːrˈkiːən/; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record. It spans 400 million years, from the end of the Hadean Eon 4 billion years ago (4000 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 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]
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.[5]
The Eoarchaean's lower boundary or starting point of 4 Gya (4 billion years ago) is officially recognized by the International Commission on Stratigraphy.[6]
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.
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.[7] These formations are presently under intense investigation.[clarification needed][8]
Atmosphere
3,850 million years old Greenland apatite 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?]
^ abPlumb, K. A. (June 1, 1991). "New Precambrian time scale". Episodes. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005. Retrieved 16 January 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. PMC3152778. 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. PMC3325685. 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. ISBN978-3-642-21625-1.
^"Eoarchean Era". geologypage.com. 16 January 2014.
^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.
^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. ISBN978-0-44-459425-9.
Further reading
Egel, R.; Lankenau, D.-H.; Mulkidjanian, A. Y. (2011). Origins of Life: The Primal Self-Organization. Berlin Heidelberg: Springer-Verlag. doi:10.1007/978-3-642-21625-1. ISBN978-3-642-21624-4.
External links
Media related to Eoarchean at Wikimedia Commons
Eoarchean (chronostratigraphy scale)
January 31, 2023
eoarchean, ɑːr, also, spelled, eoarchaean, first, archean, geologic, record, spans, million, years, from, hadean, billion, years, 4000, start, paleoarchean, 3600, beginnings, life, earth, have, been, dated, this, evidence, cyanobacteria, date, 3500, comparativ. The Eoarchean ˌ iː oʊ ɑːr ˈ k iː e n also spelled Eoarchaean is the first era of the Archean Eon of the geologic record It spans 400 million years from the end of the Hadean Eon 4 billion years ago 4000 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 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 Eoarchean4000 3600 Ma Pha Proterozoic Archean Had nChronology 4000 3950 3900 3850 3800 3750 3700 3650 3600 HadeanA r c h e a nEoarcheanPaleoarchean Events of the Eoarchean Axis scale millions of years ago EtymologyName formalityFormalAlternate spelling s EoarchaeanUsage informationCelestial bodyEarthRegional usageGlobal ICS Time scale s usedICS Time ScaleDefinitionChronological unitEraStratigraphic unitErathemTime span formalityFormalLower boundary definitionDefined ChronometricallyLower GSSA ratified1991 1 Upper boundary definitionDefined ChronometricallyUpper GSSA ratified1991 1 Eoarchaean 3 8 b y Greenlandite specimen fuchsite quartz gneiss Nuup Kangerlua Greenland Garnet paragneiss Nuvvuagittuq Greenstone Belt Canada 4 28 Ga old the oldest known Earth rock of which direct samples are available Contents 1 Chronology 2 Geology 3 Atmosphere 4 Proposed subdivisions 5 See also 6 References 7 Further reading 8 External linksChronology EditThe 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 5 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 Gya 4 billion years ago is officially recognized by the International Commission on Stratigraphy 6 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 EditMain article Eoarchean geology 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 Quebec Canada which has been dated to be 4 280 million years ago 7 These formations are presently under intense investigation clarification needed 8 Atmosphere Edit3 850 million years old Greenland apatite 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 EditEoarchean Era 4031 3600 Mya Acastan Period 4031 3810 Mya Isuan Period 3810 3600 Mya 10 See also EditPrecambrian Supereon 4600 539 Mya Hadean Eon 4600 4000 Mya Archean Eon 4000 2500 Mya Paleoarchean Era 3600 3200 Mya Mesoarchean Era 3200 2800 Mya Neoarchean Era 2800 2500 Mya Proterozoic Eon 2500 539 Mya References Edit a b Plumb K A June 1 1991 New Precambrian time scale Episodes 14 2 139 140 doi 10 18814 epiiugs 1991 v14i2 005 Retrieved 16 January 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 Eoarchean Era geologypage com 16 January 2014 International Chronostratigraphic Chart v 2013 01 PDF International Commission on Stratigraphy January 2013 Retrieved April 6 2013 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 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 Further reading EditEgel R Lankenau D H Mulkidjanian A Y 2011 Origins of Life The Primal Self Organization Berlin Heidelberg Springer Verlag doi 10 1007 978 3 642 21625 1 ISBN 978 3 642 21624 4 External links Edit Media related to Eoarchean at Wikimedia Commons Taxonconcept stratigraphy ne A short fact sheet on the Eoarchean Eoarchean chronostratigraphy scale Retrieved from https en wikipedia org w index php title Eoarchean amp oldid 1136213103, wikipedia, wiki, book, books, library,
