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Precambrian

For the album by German band The Ocean, see Precambrian (album).
"Cryptozoic" redirects here. For the games publisher, see Cryptozoic Entertainment.

The Precambrian ( /priˈkæmbri.ən, -ˈkeɪm-/ pree-KAM-bree-ən, -⁠KAYM-;[2] or Pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinized name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.

Precambrian
4567.3 ± 0.16 – 538.8 ± 0.2 Ma
Chronology
Proposed subdivisionsSee Proposed Precambrian timeline
Etymology
Synonym(s)Cryptozoic
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitSupereon
Stratigraphic unitSupereonthem
Time span formalityInformal
Lower boundary definitionFormation of the Earth
Lower GSSA ratifiedOctober 5, 2022[1]
Upper boundary definitionAppearance of the Ichnofossil Treptichnus pedum
Upper boundary GSSPFortune Head section, Newfoundland, Canada
47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310
Upper GSSP ratified1992

The Precambrian is an informal unit of geologic time,[3] subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago (Ga) to the beginning of the Cambrian Period, about 538.8 million years ago (Ma), when hard-shelled creatures first appeared in abundance.

Overview

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Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from the Precambrian (e.g. stromatolites) are of limited biostratigraphic use.[4] This is because many Precambrian rocks have been heavily metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain deeply buried beneath Phanerozoic strata.[4][5][6]

It is thought that the Earth coalesced from material in orbit around the Sun at roughly 4,543 Ma, and may have been struck by another planet called Theia shortly after it formed, splitting off material that formed the Moon (see Giant-impact hypothesis). A stable crust was apparently in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma.[7][8]

The term "Precambrian" is used by geologists and paleontologists for general discussions not requiring a more specific eon name. However, both the United States Geological Survey[9] and the International Commission on Stratigraphy regard the term as informal.[10] Because the span of time falling under the Precambrian consists of three eons (the Hadean, the Archean, and the Proterozoic), it is sometimes described as a supereon,[11][12] but this is also an informal term, not defined by the ICS in its chronostratigraphic guide.[13]

Eozoic (from eo- "earliest") was a synonym for pre-Cambrian,[14][15] or more specifically Archean.[16]

Life forms

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Further information: Origin of life, Avalon explosion, and Earliest known life forms

A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks (Archean Eon) from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia.[17] Probable fossils 100 million years older have been found in the same area. However, there is evidence that life could have evolved over 4.280 billion years ago.[18][19][20][21] There is a fairly solid record of bacterial life throughout the remainder (Proterozoic Eon) of the Precambrian.

Complex multicellular organisms may have appeared as early as 2100 Ma.[22] However, the interpretation of ancient fossils is problematic, and "... some definitions of multicellularity encompass everything from simple bacterial colonies to badgers."[23] Other possible early complex multicellular organisms include a possible 2450 Ma red alga from the Kola Peninsula,[24] 1650 Ma carbonaceous biosignatures in north China,[25] the 1600 Ma Rafatazmia,[26] and a possible 1047 Ma Bangiomorpha red alga from the Canadian Arctic.[27] The earliest fossils widely accepted as complex multicellular organisms date from the Ediacaran Period.[28][29] A very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic Eon. By the middle of the following Cambrian Period, a very diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa. The increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life.[30][31]

While land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas.[32]

Tracks from an animal with leg-like appendages have been found in what was mud 551 million years ago.[33][34]

Emergence of life

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The RNA world hypothesis asserts that RNA evolved before coded proteins and DNA genomes.[35] During the Hadean Eon (4,567–4,031 Ma) abundant geothermal microenvironments were present that may have had the potential to support the synthesis and replication of RNA and thus possibly the evolution of a primitive life form.[36] It was shown that porous rock systems comprising heated air-water interfaces could allow ribozyme-catalyzed RNA replication of sense and antisense strands that could be followed by strand-dissociation, thus enabling combined synthesis, release and folding of active ribozymes.[36] This primitive RNA replicative system also may have been able to undergo template strand switching during replication (genetic recombination) as is known to occur during the RNA replication of extant coronaviruses.[37]

Planetary environment and the oxygen catastrophe

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Weathered Precambrian pillow lava in the Temagami Greenstone Belt of the Canadian Shield

Evidence of the details of plate motions and other tectonic activity in the Precambrian is difficult to interpret. It is generally believed that small proto-continents existed before 4280 Ma, and that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, roughly 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth".[citation needed]

The atmosphere of the early Earth is not well understood. Most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen. There is, however, evidence that an oxygen-rich atmosphere existed since the early Archean.[38]

At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism. This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have quickly combined with other elements in Earth's crust, primarily iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, and the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides.

Subdivisions

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Main article: Timetable of the Precambrian

A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed absolute dates to be assigned to specific formations and features.[39] The Precambrian is divided into three eons: the Hadean (4567.3–4031 Ma), Archean (4031-2500 Ma) and Proterozoic (2500-538.8 Ma). See Timetable of the Precambrian.

  • Proterozoic: this eon refers to the time from the lower Cambrian boundary, 538.8 Ma, back through 2500 Ma. As originally used, it was a synonym for "Precambrian" and hence included everything prior to the Cambrian boundary.[citation needed] The Proterozoic Eon is divided into three eras: the Neoproterozoic, Mesoproterozoic and Paleoproterozoic.
    • Neoproterozoic: The youngest geologic era of the Proterozoic Eon, from the Cambrian Period lower boundary (538.8 Ma) back to 1000 Ma. The Neoproterozoic corresponds to Precambrian Z rocks of older North American stratigraphy.
    • Mesoproterozoic: the middle era of the Proterozoic Eon, 1000-1600 Ma. Corresponds to "Precambrian Y" rocks of older North American stratigraphy.
    • Paleoproterozoic: oldest era of the Proterozoic Eon, 1600-2500 Ma. Corresponds to "Precambrian X" rocks of older North American stratigraphy.
  • Archean Eon: 2500-4031 Ma.
  • Hadean Eon: 4031–4567.3 Ma. This term was intended originally to cover the time before any preserved rocks were deposited, although some zircon crystals from about 4400 Ma demonstrate the existence of crust in the Hadean Eon. Other records from Hadean time come from the Moon and meteorites.[40][41]

It has been proposed that the Precambrian should be divided into eons and eras that reflect stages of planetary evolution, rather than the current scheme based upon numerical ages. Such a system could rely on events in the stratigraphic record and be demarcated by GSSPs. The Precambrian could be divided into five "natural" eons, characterized as follows:[42]

  1. Accretion and differentiation: a period of planetary formation until giant Moon-forming impact event.
  2. Hadean: dominated by heavy bombardment from about 4.51 Ga (possibly including a cool early Earth period) to the end of the Late Heavy Bombardment period.
  3. Archean: a period defined by the first crustal formations (the Isua greenstone belt) until the deposition of banded iron formations due to increasing atmospheric oxygen content.
  4. Transition: a period of continued banded iron formation until the first continental red beds.
  5. Proterozoic: a period of modern plate tectonics until the first animals.

Precambrian supercontinents

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The movement of Earth's plates has caused the formation and break-up of continents over time, including occasional formation of a supercontinent containing most or all of the landmass. The earliest known supercontinent was Vaalbara. It formed from proto-continents and was a supercontinent 3.636 billion years ago. Vaalbara broke up c. 2.845–2.803 Ga ago. The supercontinent Kenorland was formed c. 2.72 Ga ago and then broke sometime after 2.45–2.1 Ga into the proto-continent cratons called Laurentia, Baltica, Yilgarn craton and Kalahari. The supercontinent Columbia, or Nuna, formed 2.1–1.8 billion years ago and broke up about 1.3–1.2 billion years ago.[43][44] The supercontinent Rodinia is thought to have formed about 1300-900 Ma, to have included most or all of Earth's continents and to have broken up into eight continents around 750–600 million years ago.[45]

See also

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  • Phanerozoic – Fourth and current eon of the geological timescale
    • Paleozoic – First era of the Phanerozoic Eon 539–252 million years ago
    • Mesozoic – Second era of the Phanerozoic Eon: ~252–66 million years ago
    • Cenozoic – Third era of the Phanerozoic Eon

References

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  1. ^ Cohen, Kim. "New edition of the Chart - 2022-10". International Commission on Stratigraphy. Retrieved 16 January 2023.
  2. ^ "Precambrian". CollinsDictionary.com. HarperCollins. Retrieved 2023-08-30.
  3. ^ Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M., eds. (2012). The Geologic Timescale 2012. Vol. 1. Elsevier. p. 301. ISBN 978-0-44-459390-0.
  4. ^ a b Monroe, James S.; Wicander, Reed (1997). The Changing Earth: Exploring Geology and Evolution (2nd ed.). Belmont: Wadsworth Publishing Company. p. 492. ISBN 9781285981383.
  5. ^ Levin, Harold L. (2010). The earth through time (9th ed.). Hoboken, N.J.: J. Wiley. pp. 230–233. ISBN 978-0470387740. Outlined in Gore, Pamela J.W. (25 October 2005). "The Earliest Earth: 2,100,000,000 years of the Archean Eon".
  6. ^ Davis, C.M. (1964). "The Precambrian Era". Readings in the Geography of Michigan. Michigan State University.
  7. ^ "Zircons are Forever". Department of Geoscience. 2005. Archived from the original on 18 May 2019. Retrieved 28 April 2007.
  8. ^ Cavosie, Aaron J.; Valley, John W.; Wilde, Simon A. (2007). "Chapter 2.5 The Oldest Terrestrial Mineral Record: A Review of 4400 to 4000 Ma Detrital Zircons from Jack Hills, Western Australia". Developments in Precambrian Geology. 15: 91–111. doi:10.1016/S0166-2635(07)15025-8. ISBN 9780444528100.
  9. ^ U.S. Geological Survey Geologic Names Committee (2010), "Divisions of geologic time – major chronostratigraphic and geochronologic units", U.S. Geological Survey Fact Sheet 2010–3059, United States Geological Survey, p. 2, retrieved 20 June 2018
  10. ^ Fan, Junxuan; Hou, Xudong (February 2017). "Chart". International Commission on Stratigraphy. International Chronostratigraphic Chart. Retrieved 10 May 2018.
  11. ^ Senter, Phil (1 April 2013). "The Age of the Earth & Its Importance to Biology". The American Biology Teacher. 75 (4): 251–256. doi:10.1525/abt.2013.75.4.5. S2CID 85652369.
  12. ^ Kamp, Ulrich (6 March 2017). "Glaciations". International Encyclopedia of Geography: People, the Earth, Environment and Technology: 1–8. doi:10.1002/9781118786352.wbieg0612. ISBN 9780470659632.
  13. ^ "Stratigraphic Guide". International Commission on Stratigraphy. Table 3. Retrieved 9 December 2020.
  14. ^ Hitchcock, C. H. (1874). The Geology of New Hampshire. p. 511. The name Eozoic seems to have been proposed by Dr. J.W. Dawson, of Montreal, in 1865. He did not fully define the limits of its application at that time; but it seems to have been generally understood by geologists to embrace all the obscurely fossiliferous rocks older than the Cambrian.
  15. ^ Bulletin. Vol. 767. U.S. Government Printing Office. 1925. p. 3. [1888] Sir J. W. Dawson prefers the term "Eozoic" [to Archean], and would have it include all the Pre-Cambrian strata.
  16. ^ Salop, L.J. (2012). Geological Evolution of the Earth During the Precambrian. Springer. p. 9. ISBN 978-3-642-68684-9. a possibility of dividing the Precambrian history into two eons: the Eozoic, embracing the Archean Era only, and the Protozoic, comprising all the remaining Precambrian Eras.
  17. ^ Brun, Yves; Shimkets, Lawrence J. (January 2000). Prokaryotic development. ASM Press. p. 114. ISBN 978-1-55581-158-7.
  18. ^ Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; slack, John F.; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T. S. (2 March 2017). "Evidence for early life in Earth's oldest hydrothermal vent precipitates". Nature. 543 (7643): 60–64. Bibcode:2017Natur.543...60D. doi:10.1038/nature21377. PMID 28252057.
  19. ^ Zimmer, Carl (1 March 2017). "Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest". The New York Times. Retrieved 2 March 2017.
  20. ^ Ghosh, Pallab (1 March 2017). "Earliest evidence of life on Earth 'found'". BBC News. Retrieved 2 March 2017.
  21. ^ Dunham, Will (1 March 2017). "Canadian bacteria-like fossils called oldest evidence of life". Reuters. Archived from the original on March 2, 2017. Retrieved 1 March 2017.
  22. ^ Albani, Abderrazak El; Bengtson, Stefan; Canfield, Donald E.; Bekker, Andrey; Macchiarelli, Roberto; Mazurier, Arnaud; Hammarlund, Emma U.; Boulvais, Philippe; Dupuy, Jean-Jacques; Fontaine, Claude; Fürsich, Franz T.; Gauthier-Lafaye, François; Janvier, Philippe; Javaux, Emmanuelle; Ossa, Frantz Ossa; Pierson-Wickmann, Anne-Catherine; Riboulleau, Armelle; Sardini, Paul; Vachard, Daniel; Whitehouse, Martin; Meunier, Alain (July 2010). "Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago". Nature. 466 (7302): 100–104. Bibcode:2010Natur.466..100A. doi:10.1038/nature09166. PMID 20596019. S2CID 4331375.
  23. ^ Donoghue, Philip C. J.; Antcliffe, Jonathan B. (July 2010). "Origins of multicellularity". Nature. 466 (7302): 41–42. doi:10.1038/466041a. PMID 20596008. S2CID 4396466.
  24. ^ Rozanov, A. Yu.; Astafieva, M. M. (1 March 2013). "A unique find of the earliest multicellular algae in the Lower Proterozoic (2.45 Ga) of the Kola Peninsula". Doklady Biological Sciences. 449 (1): 96–98. doi:10.1134/S0012496613020051. PMID 23652437. S2CID 15774804.
  25. ^ Qu, Yuangao; Zhu, Shixing; Whitehouse, Martin; Engdahl, Anders; McLoughlin, Nicola (1 January 2018). "Carbonaceous biosignatures of the earliest putative macroscopic multicellular eukaryotes from 1630 Ma Tuanshanzi Formation, north China". Precambrian Research. 304: 99–109. Bibcode:2018PreR..304...99Q. doi:10.1016/j.precamres.2017.11.004.
  26. ^ Bengtson, Stefan; Sallstedt, Therese; Belivanova, Veneta; Whitehouse, Martin (14 March 2017). "Three-dimensional preservation of cellular and subcellular structures suggests 1.6 billion-year-old crown-group red algae". PLOS Biology. 15 (3): e2000735. doi:10.1371/journal.pbio.2000735. PMC 5349422. PMID 28291791.
  27. ^ Gibson, Timothy M; Shih, Patrick M; Cumming, Vivien M; Fischer, Woodward W; Crockford, Peter W; Hodgskiss, Malcolm S.W; Wörndle, Sarah; Creaser, Robert A; Rainbird, Robert H; Skulski, Thomas M; Halverson, Galen P (2017). "Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis" (PDF). Geology. 46 (2): 135–138. doi:10.1130/G39829.1.
  28. ^ Laflamme, M. (9 September 2014). "Modeling morphological diversity in the oldest large multicellular organisms". Proceedings of the National Academy of Sciences. 111 (36): 12962–12963. Bibcode:2014PNAS..11112962L. doi:10.1073/pnas.1412523111. PMC 4246935. PMID 25114212.
  29. ^ Kolesnikov, Anton V.; Rogov, Vladimir I.; Bykova, Natalia V.; Danelian, Taniel; Clausen, Sébastien; Maslov, Andrey V.; Grazhdankin, Dmitriy V. (October 2018). "The oldest skeletal macroscopic organism Palaeopascichnus linearis". Precambrian Research. 316: 24–37. Bibcode:2018PreR..316...24K. doi:10.1016/j.precamres.2018.07.017. S2CID 134885946.
  30. ^ Fedonkin, Mikhail A.; Gehling, James G.; Grey, Kathleen; Narbonne, Guy M.; Vickers-Rich, Patricia (2007). The Rise of Animals: Evolution and Diversification of the Kingdom Animalia. Foreword by Arthur C. Clarke. Baltimore, Maryland: Johns Hopkins University Press. ISBN 978-0-8018-8679-9. LCCN 2007061351. OCLC 85162342. OL 17256629M.
  31. ^ Dawkins, Richard; Wong, Yan (2005). The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution. Houghton Mifflin Harcourt. pp. 673. ISBN 9780618619160.
  32. ^ Selden, Paul A. (2005). "Terrestrialization (Precambrian–Devonian)" (PDF). Encyclopedia of Life Sciences. John Wiley & Sons, Ltd. doi:10.1038/npg.els.0004145. ISBN 978-0470016176.
  33. ^ "Scientists discover 'oldest footprints on Earth' in southern China dating back 550 million years". Independent.co.uk. 7 June 2018. The Independent
  34. ^ Chen, Zhe; Chen, Xiang; Zhou, Chuanming; Yuan, Xunlai; Xiao, Shuhai (June 2018). "Late Ediacaran trackways produced by bilaterian animals with paired appendages". Science Advances. 4 (6): eaao6691. Bibcode:2018SciA....4.6691C. doi:10.1126/sciadv.aao6691. PMC 5990303. PMID 29881773.
  35. ^ Fine JL, Pearlman RE (August 2023). "On the origin of life: an RNA-focused synthesis and narrative". RNA. 29 (8): 1085–98. doi:10.1261/rna.079598.123. PMC 10351881. PMID 37142437.
  36. ^ a b Salditt A, Karr L, Salibi E, Le Vay K, Braun D, Mutschler H (March 2023). "Ribozyme-mediated RNA synthesis and replication in a model Hadean microenvironment". Nat Commun. 14 (1): 1495. doi:10.1038/s41467-023-37206-4. PMC 10023712. PMID 36932102.
  37. ^ Su S, Wong G, Shi W, Liu J, Lai AC, Zhou J, Liu W, Bi Y, Gao GF (June 2016). "Epidemiology, Genetic Recombination, and Pathogenesis of Coronaviruses". Trends Microbiol. 24 (6): 490–502. doi:10.1016/j.tim.2016.03.003. PMC 7125511. PMID 27012512.
  38. ^ Clemmey, Harry; Badham, Nick (1982). "Oxygen in the Precambrian Atmosphere". Geology. 10 (3): 141–146. Bibcode:1982Geo....10..141C. doi:10.1130/0091-7613(1982)10<141:OITPAA>2.0.CO;2.
  39. ^ "Geological Society of America's "2009 GSA Geologic Time Scale."". Archived from the original on 2020-11-05. Retrieved 2019-08-29.
  40. ^ Harrison, T. Mark (27 April 2009). "The Hadean Crust: Evidence from >4 Ga Zircons". Annual Review of Earth and Planetary Sciences. 37 (1): 479–505. Bibcode:2009AREPS..37..479H. doi:10.1146/annurev.earth.031208.100151.
  41. ^ Abramov, Oleg; Kring, David A.; Mojzsis, Stephen J. (October 2013). "The impact environment of the Hadean Earth". Geochemistry. 73 (3): 227–248. Bibcode:2013ChEG...73..227A. doi:10.1016/j.chemer.2013.08.004.
  42. ^ Bleeker, W. (2004) [2004]. "Toward a "natural" Precambrian time scale". In Felix M. Gradstein; James G. Ogg; Alan G. Smith (eds.). A Geologic Time Scale 2004. Cambridge University Press. ISBN 978-0-521-78673-7. also available at Stratigraphy.org: Precambrian subcommission
  43. ^ Zhao, Guochun; Cawood, Peter A.; Wilde, Simon A.; Sun, M. (2002). "Review of global 2.1–1.8 Ga orogens: implications for a pre-Rodinia super-continent". Earth-Science Reviews. 59 (1): 125–162. Bibcode:2002ESRv...59..125Z. doi:10.1016/S0012-8252(02)00073-9.
  44. ^ Zhao, Guochun; Sun, M.; Wilde, Simon A.; Li, S.Z. (2004). "A Paleo-Mesoproterozoic super-continent: assembly, growth and breakup". Earth-Science Reviews (Submitted manuscript). 67 (1): 91–123. Bibcode:2004ESRv...67...91Z. doi:10.1016/j.earscirev.2004.02.003.
  45. ^ Li, Z. X.; Bogdanova, S. V.; Collins, A. S.; Davidson, A.; De Waele, B.; Ernst, R. E.; Fitzsimons, I. C. W.; Fuck, R. A.; Gladkochub, D. P.; Jacobs, J.; Karlstrom, K. E.; Lul, S.; Natapov, L. M.; Pease, V.; Pisarevsky, S. A.; Thrane, K.; Vernikovsky, V. (2008). "Assembly, configuration, and break-up history of Rodinia: A synthesis" (PDF). Precambrian Research. 160 (1–2): 179–210. Bibcode:2008PreR..160..179L. doi:10.1016/j.precamres.2007.04.021. Archived from the original (PDF) on 4 March 2016. Retrieved 6 February 2016.

Further reading

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  • Valley, John W., William H. Peck, Elizabeth M. King (1999) Zircons Are Forever, The Outcrop for 1999, University of Wisconsin-Madison Wgeology.wisc.edu Archived 2012-03-16 at the Wayback Machine – Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago Accessed Jan. 10, 2006
  • Wilde, S. A.; Valley, J. W.; Peck, W. H.; Graham, C. M. (2001). "Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago". Nature. 409 (6817): 175–178. Bibcode:2001Natur.409..175W. doi:10.1038/35051550. PMID 11196637. S2CID 4319774.
  • Wyche, S.; Nelson, D. R.; Riganti, A. (2004). "4350–3130 Ma detrital zircons in the Southern Cross Granite–Greenstone Terrane, Western Australia: implications for the early evolution of the Yilgarn Craton". Australian Journal of Earth Sciences. 51 (1): 31–45. Bibcode:2004AuJES..51...31W. doi:10.1046/j.1400-0952.2003.01042.x.
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