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Akilia Island is an island in southwestern Greenland
Greenland

Greenland is a member country of the Kingdom of Denmark located between the Arctic Ocean and Atlantic Oceans, east of the Canadian Arctic Archipelago....
, about 22 kilometers south of Nuuk
Nuuk

Nuuk is the Capital and largest city of Greenland, and the seat of government for the Sermersooq municipality. It has a population of 15,047 , of whom 11,862 were born in Greenland....
 (Godthåb), at . Akilia is the location of a rock formation that has been proposed to contain the oldest known sedimentary rock
Sedimentary rock

Sedimentary rock is one of the three main Rock types . Sedimentary rock is formed by deposition and consolidation of mineral and organic material and from precipitation of minerals from solution....
s on Earth,

and perhaps the oldest evidence of life on Earth
Life on Earth

Life on Earth: A Natural History by David Attenborough is a groundbreaking television natural history series made by the BBC in association with Warner Bros....
.
rocks in question are part of a metamorphosed
Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
 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
Hadean

The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
 eon - based on the age of an igneous band that cuts the rock.

The supracrustal sequence contains layers rich in iron
Iron(II) oxide

Iron oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted iron, is one of the iron oxides. It is a black-colored powder with the chemical formula ....
 and silica
Silicon dioxide

The chemical compound 'silicon dioxide', also known as 'silica' , is an oxide of silicon with a chemical formula of and has been known for its hardness since antiquity....
, which are variously interpreted as banded iron formation
Banded iron formation

Banded iron formations are a distinctive type of rock often found in primordial sedimentary rocks. The structures consist of repeated thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert....
, chemical sediments from submarine hot springs
Black smoker

A black smoker or sea vent, is a type of hydrothermal vent found on the ocean floor. They are formed in fields hundreds of meters wide when superheating water from below Earth's Crust comes through the ocean floor....
, or hydrothermal
Hydrothermal circulation

Hydrothermal circulation in its most general sense is the circulation of hot water; 'hydros' in the Greek meaning water and 'thermos' meaning heat....
 vein deposits.






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Encyclopedia


Akilia Island is an island in southwestern Greenland
Greenland

Greenland is a member country of the Kingdom of Denmark located between the Arctic Ocean and Atlantic Oceans, east of the Canadian Arctic Archipelago....
, about 22 kilometers south of Nuuk
Nuuk

Nuuk is the Capital and largest city of Greenland, and the seat of government for the Sermersooq municipality. It has a population of 15,047 , of whom 11,862 were born in Greenland....
 (Godthåb), at . Akilia is the location of a rock formation that has been proposed to contain the oldest known sedimentary rock
Sedimentary rock

Sedimentary rock is one of the three main Rock types . Sedimentary rock is formed by deposition and consolidation of mineral and organic material and from precipitation of minerals from solution....
s on Earth,

and perhaps the oldest evidence of life on Earth
Life on Earth

Life on Earth: A Natural History by David Attenborough is a groundbreaking television natural history series made by the BBC in association with Warner Bros....
.

Geology

The rocks in question are part of a metamorphosed
Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
 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
Hadean

The Hadean is the Eon before the Archean. It started at Earth formation about 4.6 billion years ago , and ended roughly 3.8 billion years ago, though the latter date varies according to different sources....
 eon - based on the age of an igneous band that cuts the rock.

The supracrustal sequence contains layers rich in iron
Iron(II) oxide

Iron oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted iron, is one of the iron oxides. It is a black-colored powder with the chemical formula ....
 and silica
Silicon dioxide

The chemical compound 'silicon dioxide', also known as 'silica' , is an oxide of silicon with a chemical formula of and has been known for its hardness since antiquity....
, which are variously interpreted as banded iron formation
Banded iron formation

Banded iron formations are a distinctive type of rock often found in primordial sedimentary rocks. The structures consist of repeated thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert....
, chemical sediments from submarine hot springs
Black smoker

A black smoker or sea vent, is a type of hydrothermal vent found on the ocean floor. They are formed in fields hundreds of meters wide when superheating water from below Earth's Crust comes through the ocean floor....
, or hydrothermal
Hydrothermal circulation

Hydrothermal circulation in its most general sense is the circulation of hot water; 'hydros' in the Greek meaning water and 'thermos' meaning heat....
 vein deposits. Carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 in the rock, present as graphite
Graphite

The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Greek language ??afe?? : "to draw/write", for its use in pencils, where it is commonly called lead, as distinguished from the actual metallic element lead....
, shows low levels of carbon-13
Carbon-13

Carbon-13 is a natural, Stable isotope isotope of carbon and one of the environmental isotopes. It makes up about 1.1% of all natural carbon on Earth....
, which may suggest an origin as isotopically
Stable isotope

Stable isotopes are chemical Isotope that are not radioactive . By this definition, there are 256 known stable isotopes of the 80 elements which have one or more stable isotopes....
 light organic matter derived from living organisms.

However, this interpretation is complicated because of high-grade metamorphism
Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
 that affected the Akilia rocks after their formation. The sedimentary origin, age and the carbon content of the rocks have been questioned.

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. Research is ongoing.

See also

  • Origin of life


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