View source for Akilia

{{Short description|Island in southwestern Greenland}}
{{Infobox islands
| name                              = Akilia Island
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| image_map_caption                 = Map of Akilia Island
| pushpin_map                       = Greenland
| pushpin_label                     = Akilia Island
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| pushpin_map_caption               = Location of the Akilia Island in Greenland
| coordinates                       = {{coord|63|56|23|N|51|40|29|W|display=title,inline}}
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| archipelago                       = 
| waterbody                         = [[Davis Strait]]
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| area_ha                           = 138
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| country                           = [[Greenland]]
| country_admin_divisions_title     = [[Administrative divisions of Greenland|Municipality]]
| country_admin_divisions           = [[Sermersooq]]
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| population_as_of                  = 2023
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}}
'''Akilia Island''' is an island in southwestern [[Greenland]], about 22 kilometers south of [[Nuuk]]. Akilia is the location of a rock formation that has been proposed to contain the oldest known [[sedimentary rock]]s on Earth,<ref>
McGregor, VR,  Mason, B (1977 ''Petrogenesis and geochemistry of metabasaltic and metasedimentary enclaves in the Amîtsoq gneisses, West Greenland''. American Mineralogist, v. 62, p. 887-904</ref><ref>Nutman AP, Mojzsis, SJ, Friend, CRL (1997) ''Recognition of ≥3850 Ma water-lain sediments in West Greenland and their significance for the early Archaean Earth''. Geochimica et Cosmochimica Acta, v. 61, p. 2475-2484.
</ref> and perhaps the oldest evidence of [[life|life on Earth]].<ref name=mojzsis>Mojzsis, SJ, Arrhenius, G, McKeegan, KD, Harrison, TM, Nutman, AP, Friend, CRL (1996) ''Evidence for life on Earth before 3,800 million years ago''. Nature, v. 384, p. 55-59</ref>

==Geology==
The rocks in question are part of a [[metamorphism|metamorphosed]] [[supracrustal]] sequence located at the south-western tip of the island. The sequence has been dated as no younger than 3.85 billion years old - that is,  in the [[Hadean]] eon - based on the age of an [[igneous]] band that cuts the rock.<ref>Manning, CE, Mojzsis, SJ, Harrison, TM (2006) ''Geology, age and origin of supracrustal rocks at Akilia, West Greenland''. American Journal of Science, v. 206, p. 303-366</ref>  The supracrustal sequence contains layers rich in [[Iron(II) oxide|iron]] and [[Silicon dioxide|silica]], which are variously interpreted as [[banded iron formation]], chemical sediments from [[Black smoker|submarine hot springs]], or [[Hydrothermal circulation|hydrothermal]] vein deposits. [[Carbon]] in the rock, present as [[graphite]], shows low levels of [[carbon-13]],<ref name="mojzsis" /> which may suggest an origin as [[stable isotope|isotopically]] light organic matter derived from living organisms.<ref>Schidlowski, M (1988) ''A 3,850-Million-Year Isotopic Record of Life From Carbon in Sedimentary-Rocks''. Nature, v. 333, p. 313-318</ref>  
However, this interpretation is complicated because of high-grade [[metamorphism]] that  affected the Akilia rocks after their formation. The sedimentary origin, age and the carbon content of the rocks have been questioned.<ref>Myers, JS, Crowley, JL (2000) ''Vestiges of life in the oldest Greenland rocks? A review of early Archean geology in the Godthåbsfjord region, and reappraisal of field evidence for >3850 Ma life on Akilia''. Precambrian Research, v. 103, p. 101-124.</ref><ref>
Fedo, CM, Whitehouse, MJ (2002) ''Metasomatic origin of quartz-pyroxene rock, Akilia, Greenland, and implications for Earth's earliest life''. Science, v. 296, p. 1448-1452</ref><ref>Lepland, A, van Zuilen, M, Arrhenius, G, Whitehouse, M,  Fedo, C (2005) ''Questioning the evidence for Earth's earliest life—Akilia revisited''. Geology, v. 33, p. 77-79</ref>

If the Akilia rocks do show evidence of life by 3.85 Ga, it would challenge models which suggest that Earth would not be hospitable to life at this time.

==See also==
*[[List of islands of Greenland]]
*[[Origin of life]]

==References==
<references/>

==External links==
* [https://web.archive.org/web/20050307112059/http://www.space.com/scienceastronomy/generalscience/oldest_life_021014.html Scientists Disagree over How, When Life Began on Earth]
* [https://web.archive.org/web/20050225061248/http://www.explorenorth.com/library/communities/bl-nuuk.htm Information on Nuuk, Greenland]
* [https://www.sciencedaily.com/releases/2004/12/041219171437.htm Study Resolves Doubt About Origin Of Earth’s Oldest Rocks, Possibility Of Finding Traces Of Ancient Life]
* [http://www.eurekalert.org/pub_releases/2006-07/uoc--uss072006.php ''UCLA scientists strengthen case for life more than 3.8 billion years ago'']

[[Category:Geology of Greenland]]
[[Category:Islands of Greenland]]
[[Category:Origin of life]]
[[Category:Archean]]