Wikipedia

Isua Greenstone Belt

(Redirected from Isua greenstone belt)

The Isua Greenstone Belt is an Archean greenstone belt in southwestern Greenland, aged between 3.7 and 3.8 billion years.[2] The belt contains variably metamorphosed mafic volcanic and sedimentary rocks, and is the largest exposure of Eoarchaean supracrustal rocks on Earth.[3] Due to its age and low metamorphic grade [4] relative to many Eoarchaean rocks, the Isua Greenstone Belt has become a focus for investigations on the emergence of life[5][6] and the style of tectonics that operated on the early Earth.[7][8]

Isua Greenstone Belt
The general location of the Isua Greenstone belt (Nuuk Region)
Dimensions
Length35 km (22 mi)[1][2]
Geography
CountryGreenland
Geology
Rock ageArchean
Rock type(s)tonalite, mafic rocks, metasedimentary rocks, banded iron formations, granite and granodiorite

Overview

edit

The Isua Greenstone Belt, also known as the Isua supracrustal belt since it is composed primarily of supracrustal rocks, is located in southwestern Greenland, in the Isukasia terrane,[1] near the Nuuk capital region.[9] It forms the largest supracrustal enclave in the Itsaq Gneiss Complex, which predominantly comprises 3850 - 3600 million year old (Ma) felsic orthogneisses.[10] The greenstone belt comprises two major sequences of metamorphosed mafic volcanic and sedimentary rocks, which were divided on the basis of zircon uranium-lead dating. These sequences are the 'southern terrane', which has an age of approximately 3800 Ma, and the 'northern terrane', which has an age of approximately 3700 Ma.[3] The younger southern terrane is further subdivided into two subterranes: one predominantly comprising boninite-like metavolcanic rocks, and the other comprising tholeiitic and picritic metavolcanics.[3] The Isua Greenstone Belt is bounded to the West by the Ivinnguit Fault, which divides the Eoarachaean Itsaq Gneiss Complex from younger (Mesoarchaean) rocks of the Akia Terrane. Elsewhere, it is bounded by felsic orthogneisses of the Itsaq Gneiss Complex. These show a similar age division to the supracrustal rocks of the Isua Greenstone Belt itself, with 3800 Ma gneisses to the south of the belt, and 3700 Ma gneisses to the north of the belt.[3]

Scientific methods

edit

A large number of geological and geochemical methods have been applied to the rocks of the Isua Greenstone Belt. These include subdivision of the various lithologies and units within the belt using a combination of geological mapping and U-Pb zircon dating, typically using sensitive high-resolution ion microprobe (SHRIMP), analyses;[3] major and trace element chemistry;[11][12] structural analyses;[6][7][13] geothermobarometry and metamorphic modelling using phase diagrams to determine metamorphic conditions;[4][14] and a wide range of stable,[15][16] radiogenic,[17] and short-lived isotope systems.[18]

Lithologies

edit
 
Map showing the location of the Isua Greenstone Belt (ISB, top right) within the Itsaq Gneiss Complex. Also shown are the younger Akia Terrane to the northwest, and Tasiusasuaq Terrane to the south. Modified from Nutman et al., 2007 and Naerra et al., 2012.[2][19]

The Isua Greenstone Belt comprises many different lithologies. The most abundant rock types are mafic metavolcanic rocks with a range of compositions from boninite-like to tholeiites and picrites. Though boninitic amphibolites at Isua are often interpreted as evidence for the action of plate tectonics,[20] these are not true boninites [12] and non-plate tectonic models can also account for their formation.[11] Texturally, the mafic metavolcanics include pillow lavas and pillow breccias, which indicate that the lavas erupted subaqueously, and requires the presence of surface water during the Eoarchaean. More felsic volcanic compositions have been observed, but it is not clear whether these represent volcanic or sedimentary rocks,[3] and the only examples of potential andesite are significantly weathered.[21]

The mafic volcanic sequences contain abundant meta-ultramafic rocks, including amphibolites, serpentinites, carbonated-peridotites and peridotite.[22] The majority of these are widely accepted to be intrusive in origin, representing ultramafic cumulates.[22] Some peridotite lenses have been interpreted as obducted mantle fragments,[23] and used as evidence to support the operation of plate tectonics during the formation of the Isua Greenstone Belt. However, this interpretation is contested, and some studies suggest that all peridotites at Isua are cumulates, representing shallow level magma chambers and conduits with the volcanic sequences.[24]

Metasedimentary rocks include banded iron formation and detrital quartzite, likely representing a metamorphosed siliciclastic sedimentary rock.[3][25] Although they do not form part of the supracrustal belt itself, the belt is hosted in and in places intruded by tonalite-trondhjemite-granodiorite (TTG) orthogneisses.

 
Cartoon of the age of various rock types formed during the evolution of the Isua Greenstone Belt. Note that the y-axis does not have a scale and vertical placement of the different lithologies has no significance.[2]

Tectonics

edit

The tectonic setting in which the Isua Greenstone Belt formed remains contentious. Ideas can be broadly divided into plate tectonic models, in which the belt formed in one of several possible tectonic settings that exist on the modern day Earth,[8][26] and non-plate tectonic or non-uniformitarian models, in which the Isua Greenstone Belt formed in a tectonic regime that was different to the modern day Earth.[7] Plate tectonic models can be further subdivided into those that argue that the Isua Greenstone Belt or parts of it represent an ophiolite,[8][26] a sliver of obducted oceanic crust and mantle, and those that argue that the belt represents an accretionary prism,[13][27] formed in a subduction zone. Non-plate tectonic models generally suggest a heat pipe or mantle plume origin for the belt.[7][11] This forms part of a much broader debate about when plate tectonics emerged on Earth, and whether the Archaean Earth operated under a fundamentally different tectonic regime.

Ophiolite controversy

edit

Furnes et al. (2007) suggested that the presence of pillow lavas and closely spaced parallel dykes indicated that the Isua Greenstone Belt represented an ophiolite.[8] The interpretation of the parallel dykes as a sheeted dyke complex was particularly important as sheeted dyke complexes are diagnostic of oceanic crust in ophiolites on the modern Earth. However, this interpretation was strongly contested on the basis that the sheeted dykes proposed by Furnes et al. were in fact a much younger generation of dykes, the ~3.5 billion year old (Ga) Ameralik dykes, and therefore unrelated to pillow lavas and other volcanic rocks of the belt.[21][28] Other objections related to the composition of the dykes, which are unlike those found in modern-day ophiolites.[29]

Despite the disagreement on the presence of a sheeted dyke complex at Isua, alternative lines of evidence have been proposed in support of an ophiolite origin for the belt. These are primarily based on the geochemistry of the volcanic rocks in the belt: tholeiitic amphibolites have been interpreted as metamorphosed island-arc tholeiites,[26][30][31] and boninite-like amphibolites have been interpreted to represent metamorphosed boninites.[20][26][31] However, subsequent studies have pointed out that the boninite-like amphibolites are in fact low-titanium basalts, with too little silica to classify as boninites,[12] and recent geochemical modelling suggests that the entire volcanic compositional range at Isua can be explained without requiring a plate tectonic setting.[11]

A further line of evidence used to invoke an ophiolite origin for the Isua Greenstone Belt is the presence of peridotite lenses in the volcanic sequence, particularly two dunite lenses referred to as 'lens A' and 'lens B'.[23] These were argued to represent mantle rocks on the basis of their geochemistry, textures,[32] and the presence of apparently high-pressure minerals.[23] If true, the presence of mantle rocks within the supracrustal sequence at Isua would require that these rocks had been thrust to the surface, supporting an ophiolite origin for the belt.[26] However, more recent work disputes a mantle origin for these rocks, and suggests that all features of the dunite lenses can be explained by them representing ultramafic cumulates formed in magma chambers that fed the eruption of volcanic rocks in the Isua Greenstone Belt.[24] If this is the case, then no thrusting is required to bring them into contact with the supracrustal rocks, and the dunite lenses do not provide evidence that the Isua Greenstone Belt is an ophiolite.

Accretionary wedge models

edit

The northeastern part of the Isua Greenstone Belt has been interpreted as part of an accretionary wedge on the basis of numerous small faults and apparent repetitions of the supracrustal sequence, with similarities to modern accretionary wedges.[13] This was further supported by apparent metamorphic gradients in the same part of the belt, that are similar to those observed in modern subduction zones.[27] However, this interpretation has been strongly contested on the basis that rock types and strain are extremely consistent across the various faults in the proposed accretionary wedge,[7] and that peak metamorphic grades are consistent across the entire belt.[4]

Non-plate tectonic models

edit

Non-plate tectonic models include heat-pipe and mantle plume models,[7][11] both of which suggest that the volcanic sequences at Isua formed through eruption of mantle derived magmas with minimal crustal input. In a heat-pipe model,[33] rapid eruption of volcanic rocks and the corresponding removal of melt from the mantle below causes downward movement of the lithosphere and burial of mafic rocks. The buried mafic rocks eventually heat up and melt, producing the TTGs associated with the Isua Greenstone Belt.[7] This model can account for the mafic composition of pelitic sediments at Isua, suggesting there was little felsic crust present during its formation,[11] and the relatively simple deformation and uniform metamorphic grade observed across the belt.[4][7] However, it has been criticised on a number of grounds, including the fact that there is no evidence that the 3.7 Ga volcanic rocks or TTGs ascended through the 3.8 Ga sequence, as would be expected for vertically stacked volcanism in a heat pipe model.[34]

Metamorphism

edit

Following its formation, the Isua Greenstone belt has undergone two major metamorphic episodes. The first predates the formation of the <3.5 Ga Ameralik dykes [3] and is associated with the Eoarchaean deformation at Isua. Amphibolite-facies conditions were reached across the belt between ~3.7 and 3.6 Ga.[4][14][35][36][37] Though higher pressure conditions have been suggested locally on the basis of Ti-humite group minerals in peridotites,[23][36] the reliability of these minerals to document high pressure processes has been questioned.[24] The second event also reached amphibolite-facies conditions, and appears to have been a protracted event between ~2.9 and 2.6 Ga, followed by widespread retrogression of locally varying intensity.[4][14][35][37] The effect of these two metamorphic and deformational events adds significant complexity to interpreting the primary geochemical compositions and geological structures present in the belt (e.g., see below).

Possible signs of very early life

edit

Because of its age, the Isua Greenbelt has long been the focus of studies seeking to identify signs of early terrestrial life. In 1996, geologist Steve Mojzsis and colleagues hypothesized that isotopically light carbon in the structure's carbon-rich layers was suggestive of biological activity having occurred there. "Unless some unknown abiotic process exists which is able both to create such isotopically light carbon and then selectively incorporate it into apatite grains, our results provide evidence for the emergence of life on Earth by at least 3,800 Myr before present."[15]

In August 2016, an Australia-based research team presented evidence that the Isua Greenstone Belt contains the remains of stromatolite microbial colonies that formed approximately 3.7 billion years ago.[38][39] However, their interpretations are controversial.[38][40][41] If these structures are stromatolites, they predate the oldest previously known stromatolites, found in the Dresser Formation in western Australia, by 220 million years.[38]

The complexity of the stromatolites found at Isua, if they are indeed stromatolites, suggest that life on Earth was already sophisticated and robust by the time of their formation, and that the earliest life on Earth likely evolved over 4 billion years ago.[38] This conclusion is supported in part by the instability of Earth's surface conditions 3.7 billion years ago, which included intense asteroid bombardment.[42] The possible formation and preservation of fossils from this period indicate that life may have evolved early and prolifically in Earth's history.[42]

The stromatolite fossils appear wavy and dome-shaped, are typically 1–4 cm (0.4–1.6 in) high, and were found in iron- and magnesium-rich dolomites that had recently been exposed by melting snow.[39] The surrounding rocks suggest that the stromatolites may have been deposited in a shallow marine environment.[38] While most rocks in the Isua Greenstone Belt are too metamorphically altered to preserve fossils, the area of stromatolite discovery may have preserved original sedimentary rocks and the fossils inside them.[42] However, some geologists interpret the structures as the result of deformation and alteration of the original rock.[40]

The ISB sedimentary layers containing the possible stromatolites overlay volcanic rocks that are dated to 3.709 billion years old and are capped by dolomite and banded iron formations with thorium-uranium zircons dated to 3.695 ± 0.4 billion years old. All layers, including those bordering the stromatolites, experienced metamorphism and deformation after deposition, and temperatures not exceeding 550 °C (1,000 °F).[38][40]

The identity of the ISB features as stromatolites is controversial, because similar features may form through non-biological processes.[42][40] Some geologists interpret the textures above the putative stromatolites as sand accumulation against their sides during their formation, suggesting that the features arose during the sedimentary process, and not through later, metamorphic deformation.[41][38][42] However, others suggest that the rocks are so altered that any sedimentary interpretations are inappropriate.[40]

In 2016, geologist and areologist Abigail Allwood stated that the discovery of Isua stromatolites makes the emergence of life on other planets, including Mars early after its formation, more probable.[42] However, in 2018, she and a team of additional geologists published a paper that raises significant questions as to the origin of the structures, interpreting them as arising from deformation.[40] Thus, the ISB stromatolites remain a subject of ongoing investigation.[39]

See also

edit

References

edit
  1. ^ a b Bennett, Vickie C.; Nutman, Allen P. (April 2014). "Isua Supracrustal Belt, West Greenland: Geochronology". Encyclopedia of Scientific Dating Methods. pp. 1–4. doi:10.1007/978-94-007-6326-5_109-1. ISBN 978-94-007-6326-5.
  2. ^ a b c d Nutman, Allen P.; Friend, Clark R.L.; Horie, Kenji; Hidaka, Hiroshi (2007). The Itsaq Gneiss Complex of Southern West Greenland and the Construction of Eorarchean Crust at Convergent Plate Boundaries (PDF). Developments in Precambrian Geology. Vol. 15. pp. 187–218. doi:10.1016/S0166-2635(07)15033-7. ISBN 9780444528100. Retrieved 3 September 2016.
  3. ^ a b c d e f g h Nutman, Allen P.; Friend, Clark R. L. (2009-08-01). "New 1:20,000 scale geological maps, synthesis and history of investigation of the Isua supracrustal belt and adjacent orthogneisses, southern West Greenland: A glimpse of Eoarchaean crust formation and orogeny". Precambrian Research. 172 (3): 189–211. Bibcode:2009PreR..172..189N. doi:10.1016/j.precamres.2009.03.017. ISSN 0301-9268.
  4. ^ a b c d e f Ramírez-Salazar, Anthony; Müller, Thomas; Piazolo, Sandra; Webb, A. Alexander G.; Hauzenberger, Christoph; Zuo, Jiawei; Haproff, Peter; Harvey, Jason; Wong, Tsz Kin; Charlton, Callum (2021). "Tectonics of the Isua Supracrustal Belt 1: P-T-X-d Constraints of a Poly-Metamorphic Terrane". Tectonics. 40 (3): e2020TC006516. Bibcode:2021Tecto..4006516R. doi:10.1029/2020TC006516. ISSN 1944-9194. S2CID 234022542.
  5. ^ Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Van Kranendonk, Martin J.; Chivas, Allan R. (September 2016). "Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures". Nature. 537 (7621): 535–538. Bibcode:2016Natur.537..535N. doi:10.1038/nature19355. ISSN 1476-4687. PMID 27580034. S2CID 205250494.
  6. ^ a b Allwood, Abigail C.; Rosing, Minik T.; Flannery, David T.; Hurowitz, Joel A.; Heirwegh, Christopher M. (November 2018). "Reassessing evidence of life in 3,700-million-year-old rocks of Greenland". Nature. 563 (7730): 241–244. Bibcode:2018Natur.563..241A. doi:10.1038/s41586-018-0610-4. ISSN 1476-4687. PMID 30333621. S2CID 52987320.
  7. ^ a b c d e f g h A. Alexander G. Webb, Thomas Müller, Jiawei Zuo, Peter J. Haproff, and Anthony Ramírez-Salazar (2020). "A non–plate tectonic model for the Eoarchean Isua supracrustal belt". Lithosphere. 12 (1): 166–179. Bibcode:2020Lsphe..12..166W. doi:10.1130/L1130.1. S2CID 213886867.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ a b c d Furnes, Harald; de Wit, Maarten; Staudigel, Hubert; Rosing, Minik; Muehlenbachs, Karlis (2007-03-23). "A Vestige of Earth's Oldest Ophiolite". Science. 315 (5819): 1704–1707. Bibcode:2007Sci...315.1704F. doi:10.1126/science.1139170. ISSN 0036-8075. PMID 17379806. S2CID 11691449.
  9. ^ Bennett, Vickie C.; Nutman, Allen P. (2014). "Isua Supracrustal Belt, West Greenland: Geochronology". Encyclopedia of Scientific Dating Methods. Australia. p. 1. doi:10.1007/978-94-007-6326-5_109-1. ISBN 978-94-007-6326-5.{{cite book}}: CS1 maint: location missing publisher (link)
  10. ^ Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Horie, Kenji; Hidaka, Hiroshi (2007-08-21). "~3,850 Ma tonalites in the Nuuk region, Greenland: geochemistry and their reworking within an Eoarchaean gneiss complex". Contributions to Mineralogy and Petrology. 154 (4): 385–408. Bibcode:2007CoMP..154..385N. doi:10.1007/s00410-007-0199-3. ISSN 0010-7999. S2CID 52855243.
  11. ^ a b c d e f Rollinson, Hugh (2022). "No plate tectonics necessary to explain Eoarchean rocks at Isua (Greenland)". Geology. 50 (2): 147–151. Bibcode:2022Geo....50..147R. doi:10.1130/G49278.1.
  12. ^ a b c Julian A. Pearce and Mark K. Reagan (2019). "Identification, classification, and interpretation of boninites from Anthropocene to Eoarchean using Si-Mg-Ti systematics". Geosphere. 15 (4): 1008–1037. Bibcode:2019Geosp..15.1008P. doi:10.1130/GES01661.1. S2CID 195803899.
  13. ^ a b c Komiya, Tsuyoshi; Maruyama, Shigenori; Masuda, Toshiaki; Nohda, Susumu; Hayashi, Mamoru; Okamoto, Kazuaki (1999-09-01). "Plate Tectonics at 3.8–3.7 Ga: Field Evidence from the Isua Accretionary Complex, Southern West Greenland". The Journal of Geology. 107 (5): 515–554. Bibcode:1999JG....107..515K. doi:10.1086/314371. ISSN 0022-1376. PMID 10504134. S2CID 24418938.
  14. ^ a b c Rollinson, Hugh (5 February 2003). "Metamorphic history suggested by garnet-growth chronologies in the Isua Greenstone Belt, West Greenland". Precambrian Research. 126 (3–4): 181–196. Bibcode:2003PreR..126..181R. doi:10.1016/s0301-9268(03)00094-9.
  15. ^ a b Mojzsis SJ, Arrhenius G, McKeegan KD, Harrison TM, Nutman AP, Friend CR (1996). "Evidence for life on Earth before 3,800 million years ago". Nature. 384 (6604): 55–59. Bibcode:1996Natur.384...55M. doi:10.1038/384055a0. hdl:2060/19980037618. PMID 8900275. S2CID 4342620.
  16. ^ Kurzweil, F.; Münker, C.; Hoffmann, J.E.; Tusch, J.; Schoenberg, R. (July 2020). "Stable W isotope evidence for redistribution of homogeneous 182W anomalies in SW Greenland". Geochemical Perspectives Letters. 14: 53–57. Bibcode:2020GChPL..14...53K. doi:10.7185/geochemlet.2024. S2CID 225595453.
  17. ^ Hoffmann, J. Elis; Münker, Carsten; Polat, Ali; König, Stephan; Mezger, Klaus; Rosing, Minik T. (December 2010). "Highly depleted Hadean mantle reservoirs in the sources of early Archean arc-like rocks, Isua supracrustal belt, southern West Greenland". Geochimica et Cosmochimica Acta. 74 (24): 7236–7260. Bibcode:2010GeCoA..74.7236H. doi:10.1016/j.gca.2010.09.027.
  18. ^ Willbold, Matthias; Elliott, Tim; Moorbath, Stephen (September 2011). "The tungsten isotopic composition of the Earth's mantle before the terminal bombardment". Nature. 477 (7363): 195–198. Bibcode:2011Natur.477..195W. doi:10.1038/nature10399. ISSN 0028-0836. PMID 21901010. S2CID 4419046.
  19. ^ Naerra, T.; Schersten, A.; Rosing, M. T.; Kemp, A. I. S.; Hoffman, J. E.; Kokfelt, T.F.; Whitehouse, M. J. (May 2012). "Hafnium isotope evidence for a transition in the dynamics of continental growth 3.2 Gyr ago". Nature. 485 (7400): 627–630. Bibcode:2012Natur.485..627N. doi:10.1038/nature11140. PMID 22660324. S2CID 205228999.
  20. ^ a b Polat, A; Hofmann, A. W; Rosing, M. T (2002-04-01). "Boninite-like volcanic rocks in the 3.7–3.8 Ga Isua greenstone belt, West Greenland: geochemical evidence for intra-oceanic subduction zone processes in the early Earth". Chemical Geology. 184 (3): 231–254. Bibcode:2002ChGeo.184..231P. doi:10.1016/S0009-2541(01)00363-1. ISSN 0009-2541.
  21. ^ a b Friend, C. R. L.; Nutman, A. P. (2010-11-01). "Eoarchean ophiolites? New evidence for the debate on the Isua supracrustal belt, southern West Greenland". American Journal of Science. 310 (9): 826–861. Bibcode:2010AmJS..310..826F. doi:10.2475/09.2010.04. ISSN 0002-9599. S2CID 129049164.
  22. ^ a b Szilas, Kristoffer; Kelemen, Peter B.; Rosing, Minik T. (2015-09-01). "The petrogenesis of ultramafic rocks in the >3.7Ga Isua supracrustal belt, southern West Greenland: Geochemical evidence for two distinct magmatic cumulate trends". Gondwana Research. 28 (2): 565–580. Bibcode:2015GondR..28..565S. doi:10.1016/j.gr.2014.07.010. ISSN 1342-937X.
  23. ^ a b c d Friend, C.R.L.; Nutman, A.P. (July 2011). "Dunites from Isua, Greenland: A ca. 3720 Ma window into subcrustal metasomatism of depleted mantle". Geology. 39 (7): 663–666. Bibcode:2011Geo....39..663F. doi:10.1130/G31904.1. ISSN 1943-2682.
  24. ^ a b c Waterton, P.; Guotana, J. M.; Nishio, I.; Morishita, T.; Tani, K.; Woodland, S.; Legros, H.; Pearson, D. G.; Szilas, K. (2022-02-01). "No mantle residues in the Isua Supracrustal Belt". Earth and Planetary Science Letters. 579: 117348. Bibcode:2022E&PSL.57917348W. doi:10.1016/j.epsl.2021.117348. ISSN 0012-821X. S2CID 245454643.
  25. ^ Nutman, Allen P.; Friend, Clark R.L.; Paxton, Shane (August 2009). "Detrital zircon sedimentary provenance ages for the Eoarchaean Isua supracrustal belt southern West Greenland: Juxtaposition of an imbricated ca. 3700Ma juvenile arc against an older complex with 3920–3760Ma components". Precambrian Research. 172 (3–4): 212–233. Bibcode:2009PreR..172..212N. doi:10.1016/j.precamres.2009.03.019.
  26. ^ a b c d e Friend, Clark R. L.; Nutman, Allen P. (2010-11-01). "Eoarchean ophiolites? New evidence for the debate on the Isua supracrustal belt, southern West Greenland". American Journal of Science. 310 (9): 826–861. Bibcode:2010AmJS..310..826F. doi:10.2475/09.2010.04. ISSN 0002-9599. S2CID 129049164.
  27. ^ a b Arai, Tatsuyuki; Omori, Soichi; Komiya, Tsuyoshi; Maruyama, Shigenori (2015-11-01). "Intermediate P/T-type regional metamorphism of the Isua Supracrustal Belt, southern west Greenland: The oldest Pacific-type orogenic belt?". Tectonophysics. Special issue on Comparative tectonic and dynamic analysis of cratons, orogens, basins, and metallogeny. 662: 22–39. Bibcode:2015Tectp.662...22A. doi:10.1016/j.tecto.2015.05.020. ISSN 0040-1951.
  28. ^ Nutman, Allen P.; Friend, Clark R. L. (2007-11-02). "Comment on "A Vestige of Earth's Oldest Ophiolite"". Science. 318 (5851): 746. Bibcode:2007Sci...318..746N. doi:10.1126/science.1144148. ISSN 0036-8075. PMID 17975049. S2CID 38347037.
  29. ^ Hamilton, Warren B. (2007-11-02). "Comment on "A Vestige of Earth's Oldest Ophiolite"". Science. 318 (5851): 746. Bibcode:2007Sci...318..746H. doi:10.1126/science.1144931. PMID 17975050. S2CID 3136755.
  30. ^ Polat, A; Hofmann, A. W (2003-10-10). "Alteration and geochemical patterns in the 3.7–3.8 Ga Isua greenstone belt, West Greenland". Precambrian Research. Early Archaean Processes and the Isua Geenstone Belt, West Greenland. 126 (3): 197–218. Bibcode:2003PreR..126..197P. doi:10.1016/S0301-9268(03)00095-0. ISSN 0301-9268.
  31. ^ a b Furnes, Harald; Rosing, Minik; Dilek, Yildirim; de Wit, Maarten (November 2009). "Isua supracrustal belt (Greenland)—A vestige of a 3.8 Ga suprasubduction zone ophiolite, and the implications for Archean geology". Lithos. 113 (1–2): 115–132. Bibcode:2009Litho.113..115F. doi:10.1016/j.lithos.2009.03.043.
  32. ^ Kaczmarek, Mary-Alix; Reddy, Steven M.; Nutman, Allen P.; Friend, Clark R. L.; Bennett, Vickie C. (April 2016). "Earth's oldest mantle fabrics indicate Eoarchaean subduction". Nature Communications. 7 (1): 10665. Bibcode:2016NatCo...710665K. doi:10.1038/ncomms10665. ISSN 2041-1723. PMC 4757760. PMID 26879892.
  33. ^ Moore, William B.; Webb, A. Alexander G. (September 2013). "Heat-pipe Earth". Nature. 501 (7468): 501–505. Bibcode:2013Natur.501..501M. doi:10.1038/nature12473. ISSN 0028-0836. PMID 24067709. S2CID 4391599.
  34. ^ Nutman, Allen P.; Friend, Clark R.L.; Bennett, Vickie C.; Kranendonk, Martin van; Chivas, Allan R. (June 2021). "Geodynamic environment of the ca. 3800 Ma Outer Arc Group, Isua (Greenland)". American Journal of Science. 321 (6): 643–679. Bibcode:2021AmJS..321..643N. doi:10.2475/06.2021.01. ISSN 0002-9599. S2CID 238412385.
  35. ^ a b Rollinson, Hugh (2002). "The metamorphic history of the Isua Greenstone Belt, West Greenland". Geological Society, London, Special Publications. 199 (1): 329–350. Bibcode:2002GSLSP.199..329R. doi:10.1144/gsl.sp.2002.199.01.16. ISSN 0305-8719. S2CID 129110356.
  36. ^ a b Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Yi, Keewook (2020-07-15). "Eoarchean contrasting ultra-high-pressure to low-pressure metamorphisms (1000°C/GPa) explained by tectonic plate convergence in deep time". Precambrian Research. 344: 105770. doi:10.1016/j.precamres.2020.105770. hdl:1885/224133. ISSN 0301-9268. S2CID 218921084.
  37. ^ a b Frei, Robert; Rosing, Minik T; Waight, Tod E; Ulfbeck, David G (2002-02-01). "Hydrothermal-metasomatic and tectono-metamorphic processes in the Isua supracrustal belt (West Greenland): a multi-isotopic investigation of their effects on the earth's oldest oceanic crustal sequence". Geochimica et Cosmochimica Acta. 66 (3): 467–486. Bibcode:2002GeCoA..66..467F. doi:10.1016/S0016-7037(01)00781-5. ISSN 0016-7037.
  38. ^ a b c d e f g Nutman, Allen; Bennett, Vickie; Friend, Clark; Van Kranendonk, Martin; Chivas, Allan (2016). "Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures". Nature. 537 (7621): 535–538. Bibcode:2016Natur.537..535N. doi:10.1038/nature19355. PMID 27580034. S2CID 205250494.
  39. ^ a b c Pease, Roland (31 August 2016). "Wavy Greenland rock features 'are oldest fossils'". BBC. Retrieved 31 August 2016.
  40. ^ a b c d e f Allwood, Abigail C. (2018). "Reassessing evidence of life in 3,700-million-year-old rocks of Greenland". Nature. 563 (7730): 241–244. Bibcode:2018Natur.563..241A. doi:10.1038/s41586-018-0610-4. PMID 30333621. S2CID 52987320.
  41. ^ a b Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Van Kranendonk, Martin J.; Rothacker, Leo; Chivas, Allan R. (2019-09-01). "Cross-examining Earth's oldest stromatolites: Seeing through the effects of heterogeneous deformation, metamorphism and metasomatism affecting Isua (Greenland) ~3700 Ma sedimentary rocks". Precambrian Research. 331: 105347. doi:10.1016/j.precamres.2019.105347. ISSN 0301-9268. S2CID 182575508.
  42. ^ a b c d e f Allwood, Abigail (31 August 2016). "Geology: Evidence of life in Earth's oldest rocks". News and Views. Nature.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Isua_Greenstone_Belt&oldid=1187459158"