Oldest dated rocks

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A sample of gneiss from the site of the Earth's oldest dated rocks (the Acasta River area of Canada). This sample has been dated at 4.03 billion years old. 4,030,000,000 Years Acasta Gneiss.jpg
A sample of gneiss from the site of the Earth's oldest dated rocks (the Acasta River area of Canada). This sample has been dated at 4.03 billion years old.
The Moon rock "Big Bertha", collected on the 1971 Apollo 14 mission, contains an Earth meteorite that is 4 billion years old. Big Bertha sample 14321.jpg
The Moon rock "Big Bertha", collected on the 1971 Apollo 14 mission, contains an Earth meteorite that is 4 billion years old.

The oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon, which is defined to start with the formation of the oldest intact rocks on Earth.

Contents

Archean rocks are exposed on Earth's surface in very few places, such as in the geologic shields of Canada, Australia, and Africa. The ages of these felsic rocks are generally between 2.5 and 3.8 billion years. The approximate ages have a margin of error of millions of years. In 1999, the oldest known rock on Earth was dated to 4.031 ±0.003 billion years, and is part of the Acasta Gneiss of the Slave Craton in northwestern Canada. [1] Researchers at McGill University found a rock with a very old model age for extraction from the mantle (3.8 to 4.28 billion years ago) in the Nuvvuagittuq greenstone belt on the coast of Hudson Bay, in northern Quebec; [2] the true age of these samples is still under debate, and they may actually be closer to 3.8 billion years old. [3] Older than these rocks are crystals of the mineral zircon, which can survive the disaggregation of their parent rock and be found and dated in younger rock formations.

In January 2019, NASA scientists reported the discovery of the oldest known Earth rock, found on the Moon. Apollo 14 astronauts returned several rocks from the Moon and, later, scientists determined that a fragment from a rock nicknamed Big Bertha, which had been chosen by astronaut Alan Shepard, contained "a bit of Earth from about 4 billion years ago". The rock fragment contained quartz, feldspar, and zircon, all common on Earth, but highly uncommon on the Moon. [4] Pre-solar grains in meteorites are older than the Solar System, with some grains extracted from the Murchison meteorite claimed to be 7 billion years old. [5] [6] [7]

Oldest rocks by category

Oldest terrestrial material

The oldest material of terrestrial origin that has been dated is a zircon mineral of 4.404 ±0.008 Ga enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss Terrane of Western Australia. [8] The 4.404 ±0.008 Ga zircon is a slight outlier, with the oldest consistently dated zircon falling closer to 4.35 Ga. [8] This zircon is part of a population of zircons within the metamorphosed conglomerate, which is believed to have been deposited about 3.060 Ga, which is the age of the youngest detrital zircon in the rock. Recent developments in atom-probe tomography have led to a further constraint on the age of the oldest continental zircon, with the most recent age quoted as 4.374 ±0.006 Ga. [9]

The discovery of the oldest known Earth rock, found on the Moon, was reported in January 2019 by NASA scientists. Apollo 14 astronauts returned several rocks from the Moon and, later, scientists determined that a fragment from one of the rocks, nicknamed Big Bertha, contained "a bit of Earth from about 4 billion years ago". The rock fragment contained quartz, feldspar, and zircon, all common on Earth, but highly uncommon on the Moon. [4]

Earth's oldest rock formation

The oldest outcropping rock formation is, depending on the latest research, either part of the Isua Greenstone Belt, Narryer Gneiss Terrane, Nuvvuagittuq Greenstone Belt, Napier Complex, or the Acasta Gneiss (on the Slave Craton). The difficulty in assigning the title to one particular block of gneiss is that the gneisses are all extremely deformed, and the oldest rock may be represented by only one streak of minerals in a mylonite, representing a layer of sediment or an old dike. This may be difficult to find or map; hence, the oldest dates yet resolved are as much generated by luck in sampling as by understanding the rocks themselves.

It is thus premature to claim that any of these rocks, or indeed that of other formations of Hadean gneisses, is the oldest formations or rocks on Earth; doubtless, new analyses will continue to change conceptions of the structure and nature of these ancient continental fragments.

Nevertheless, the oldest cratons on Earth include the Kaapvaal Craton, the Western Gneiss Terrane of the Yilgarn Craton (~2.9 – >3.2 Ga), the Pilbara Craton (~3.4 Ga), and portions of the Canadian Shield (~2.4 – >3.6 Ga). Parts of Dharwar Craton in India are greater than 3.0 Ga. The oldest dated rocks of the Baltic Shield are 3.5 Ga old. [10]

Other old formations include the Saglek Gneiss Complex, dated at 3.8-3.9 Ga; the Anshan Area, dated at 3.8 Ga; the Itsaq (Isua) Gneiss Complex, dated at 3.7-3.8 Ga; and the Ancient Gneiss Complex, dated at 3.6 Ga.

Oldest rock on Earth

Fragment of Acasta Gneiss Acasta Gneiss fragment.JPG
Fragment of Acasta Gneiss

The Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed in a glacial peneplain. Analyses of zircons from a felsic orthogneiss with presumed granitic protolith returned an age of 4.031 ±0.003 Ga. [1]

On September 25, 2008, researchers from McGill University, Carnegie Institution for Science and UQAM announced that a rock formation, the Nuvvuagittuq greenstone belt, exposed on the eastern shore of Hudson Bay in northern Quebec had a Sm–Nd model age for extraction from the mantle of 4.28 billion years. [11] [12] [13] [14] However, it is argued that the actual age of formation of this rock, as opposed to the extraction of its magma from the mantle, is likely closer to 3.8 billion years, according to Simon Wilde of the Institute for Geoscience Research in Australia. [3]

Hadean Zircons from the Jack Hills of Western Australian

The zircons from the Western Australian Jack Hills returned an age of 4.404 billion years, interpreted to be the age of crystallization. These zircons also show another feature; their oxygen isotopic composition has been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of Earth. The importance and accuracy of these interpretations is currently the subject of scientific debate. It may be that the oxygen isotopes and other compositional features (the rare-earth elements) record more recent hydrothermal alteration of the zircons rather than the composition of the magma at the time of their original crystallization. [15] In a paper published in the journal Earth and Planetary Science Letters, a team of scientists suggest that rocky continents and liquid water existed at least 4.3 billion years ago and were subjected to heavy weathering by an acrid climate. Using an ion microprobe to analyze isotope ratios of the element lithium in zircons from the Jack Hills in Western Australia, and comparing these chemical fingerprints to lithium compositions in zircons from continental crust and primitive rocks similar to Earth's mantle, they found evidence that the young planet already had the beginnings of continents, relatively cool temperatures and liquid water by the time the Australian zircons formed. [16]

Non-terrestrial rocks

The main fragment of meteorite NWA 11119, the oldest dated whole rock. Main mass of the Northwest Africa (NWA) 11119 meteorite.png
The main fragment of meteorite NWA 11119, the oldest dated whole rock.

One of the oldest Martian meteorites found on Earth, Allan Hills 84001 has been measured to have crystallized from molten rock 4.091 billion years ago. [17]

The Genesis Rock (Lunar sample 15415), obtained from the Moon by astronauts during Apollo 15 mission, has been dated at 4.08 billion years. [18] During Apollo 16, older rocks, including Lunar sample 67215, dated at 4.46 billion years, were brought back. [19]

Some types of meteorite are older the Earth, having formed in the early Solar System, before the planet formation process was completed. The meteorite Northwest Africa 11119 (NWA 11119) has been dated to 4.5648 ± 0.0003 billion years. [20]

Some solid inclusions within meteorites are older than the surrounding rock. Calcium-aluminium rich inclusions (CAIs) in meteorites are the oldest solids that formed in the Solar System, so are conventionally used to set its formation date as 4567.30 ± 0.16 Myr. [21] [22] Pre-solar grains are even older; they formed in the interstellar medium and pre-date the formation of the Solar System. Some pre-solar grains extracted from the Murchison meteorite have been claimed to be 7 billion years old. [6] [7]

See also

Related Research Articles

The Precambrian 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.

The Hadean is the first and oldest of the four known geologic eons of Earth's history, starting with the planet's formation about 4.6 billion years ago, and ended 4.031 billion years ago. The interplanetary collision that created the Moon occurred early in this eon. The Hadean eon was succeeded by the Archean eon, with the Late Heavy Bombardment hypothesized to have occurred at the Hadean-Archean boundary.

<span class="mw-page-title-main">Vredefort impact structure</span> Largest verified impact structure on Earth, about 2 billion years old

The Vredefort impact structure is the largest verified impact structure on Earth. The crater, which has since been eroded away, has been estimated at 170–300 kilometres (110–190 mi) across when it was formed. The remaining structure, comprising the deformed underlying bedrock, is located in present-day Free State province of South Africa. It is named after the town of Vredefort, which is near its centre. The structure's central uplift is known as the Vredefort Dome. The impact structure was formed during the Paleoproterozoic Era, 2.023 billion years ago. It is the second-oldest known impact structure on Earth, after Yarrabubba.

<span class="mw-page-title-main">Eoarchean</span> First era of the Archean Eon

The Eoarchean is the first era of the Archean Eon of the geologic record. It spans 431 million years, from the end of the Hadean Eon 4031 Mya to the start of the Paleoarchean Era 3600 Mya. Some estimates place the beginnings of life on Earth in this era, while others place it earlier. Evidence of archaea and 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.

<span class="mw-page-title-main">Acasta Gneiss</span> Metamorphic rock unit in Canada

The Acasta Gneiss Complex, also called the Acasta Gneiss, is a body of felsic to ultramafic Archean basement rocks, gneisses, that form the northwestern edge of the Slave Craton in the Northwest Territories, Canada, about 300 km (190 mi) north of Yellowknife, Canada. This geologic complex consists largely of tonalitic and granodioritic gneisses and lesser amounts of mafic and ultramafic gneisses. It underlies and is largely concealed by thin, patchy cover of Quaternary glacial sediments over an area of about 13,000 km2 (5,000 sq mi). The Acasta Gneiss Complex contains fragments of the oldest known crust and record of more than a billion years of magmatism and metamorphism. The Acasta Gneiss Complex is exposed in a set of anticlinoriums within the foreland fold and thrust belt of the Paleoproterozoic Wopmay Orogen.

<span class="mw-page-title-main">Jack Hills</span> Range of hills in Western Australia

The Jack Hills are a range of hills in Mid West Western Australia. They are best known as the source of the oldest material of terrestrial origin found to date: Hadean zircons that formed around 4.404 billion years ago. These zircons have enabled deeper research into the conditions on Earth in the Hadean eon. Potentially biogenic carbon isotope ratios have been identified for graphite embedded within a 4.1 billion-year-old zircon from the site.

<span class="mw-page-title-main">Narryer Gneiss Terrane</span> Geological complex of ancient rocks in Western Australia

The Narryer Gneiss Terrane is a geological complex in Western Australia that is composed of a tectonically interleaved and polydeformed mixture of granite, mafic intrusions and metasedimentary rocks in excess of 3.3 billion years old, with the majority of the Narryer Gneiss Terrane in excess of 3.6 billion years old. The rocks have experienced multiple metamorphic events at amphibolite or granulite conditions, resulting in often complete destruction of original igneous or sedimentary (protolith) textures. Importantly, it contains the oldest known samples of the Earth's crust: samples of zircon from the Jack Hills portion of the Narryer Gneiss have been radiometrically dated at 4.4 billion years old, although the majority of zircon crystals are about 3.6-3.8 billion years old.

<span class="mw-page-title-main">Yilgarn Craton</span> Large craton in Western Australia

The Yilgarn Craton is a large craton that constitutes a major part of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have been dated at ~4.27 Ga, with one detrital zircon dated as old as 4.4 Ga.

Early Earth is loosely defined as encompassing Earth in its first one billion years, or gigayear (Ga, 109 y), from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga. On the geologic time scale, this comprises all of the Hadean eon, starting with the formation of the Earth about 4.6 billion years ago, and the Eoarchean, starting 4 billion years ago, and part of the Paleoarchean era, starting 3.6 billion years ago, of the Archean eon.

<span class="mw-page-title-main">Slave Craton</span> Area of ancient rocks in northwest Canada

The Slave Craton is an Archaean craton in the north-western Canadian Shield, in Northwest Territories and Nunavut. The Slave Craton includes the 4.03 Ga-old Acasta Gneiss which is one of the oldest dated rocks on Earth. Covering about 300,000 km2 (120,000 sq mi), it is a relatively small but well-exposed craton dominated by ~2.73–2.63 Ga greenstones and turbidite sequences and ~2.72–2.58 Ga plutonic rocks, with large parts of the craton underlain by older gneiss and granitoid units. The Slave Craton is one of the blocks that compose the Precambrian core of North America, also known as the palaeocontinent Laurentia.

<span class="mw-page-title-main">Kaapvaal Craton</span> Archaean craton, possibly part of the Vaalbara supercontinent

The Kaapvaal Craton, along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga crust on Earth. Similarities of rock records from both these cratons, especially of the overlying late Archean sequences, suggest that they were once part of the Vaalbara supercontinent.

Supracrustal rocks are rocks that were deposited on the existing basement rocks of the crust, hence the name. They may be further metamorphosed from both sedimentary and volcanic rocks.

<span class="mw-page-title-main">Nuvvuagittuq Greenstone Belt</span> Geologic sequence in Quebec, Canada

The Nuvvuagittuq Greenstone Belt is a sequence of metamorphosed mafic to ultramafic volcanic and associated sedimentary rocks located on the eastern shore of Hudson Bay, 40 km southeast of Inukjuak, Quebec. These rocks have undergone extensive metamorphism, and represent some of the oldest surface rocks on Earth.

<span class="mw-page-title-main">Late Heavy Bombardment</span> Hypothesized astronomical event

The Late Heavy Bombardment (LHB), or lunar cataclysm, is a hypothesized astronomical event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth. According to the hypothesis, during this interval, a disproportionately large number of asteroids and comets collided into the terrestrial planets and their natural satellites in the inner Solar System, including Mercury, Venus, Earth and Mars. These came from both post-accretion and planetary instability-driven populations of impactors. Although it gained widespread credence, definitive evidence remains elusive.

<span class="mw-page-title-main">Huangling Anticline</span> Group of rock units in the Yangtze Block, South China

The Huangling Anticline or Complex represents a group of rock units that appear in the middle of the Yangtze Block in South China, distributed across Yixingshan, Zigui, Huangling, and Yichang counties. The group of rock involves nonconformity that sedimentary rocks overlie the metamorphic basement. It is a 73-km long, asymmetrical dome-shaped anticline with axial plane orientating in the north-south direction. It has a steeper west flank and a gentler east flank. Basically, there are three tectonic units from the anticline core to the rim, including Archean to Paleoproterozoic metamorphic basement, Neoproterozoic to Jurassic sedimentary rocks, and Cretaceous fluvial deposit sedimentary cover. The northern part of the core is mainly tonalite-trondhjemite-gneiss (TTG) and Cretaceous sedimentary rock called the Archean Kongling Complex. The middle of the core is mainly the Neoproterozoic granitoid. The southern part of the core is the Neoproterozoic potassium granite. Two basins are situated on the western and eastern flanks of the core, respectively, including the Zigui basin and Dangyang basin. Both basins are synforms while Zigui basin has a larger extent of folding. Yuanan Graben and Jingmen Graben are found within the Dangyang Basin area. The Huangling Anticline is an important area that helps unravel the tectonic history of the South China Craton because it has well-exposed layers of rock units from Archean basement rock to Cretaceous sedimentary rock cover due to the erosion of the anticline.

<span class="mw-page-title-main">Earliest known life forms</span> Putative fossilized microorganisms found near hydrothermal vents

The earliest known life forms on Earth may be as old as 4.1 billion years according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. The earliest evidence of life found in a stratigraphic unit, not just a single mineral grain, is the 3.7 Ga metasedimentary rocks containing graphite from the Isua Supracrustal Belt in Greenland. The earliest direct known life on land may be stromatolites which have been found in 3.480-billion-year-old geyserite uncovered in the Dresser Formation of the Pilbara Craton of Western Australia. Various microfossils of microorganisms have been found in 3.4 Ga rocks, including 3.465-billion-year-old Apex chert rocks from the same Australian craton region, and in 3.42 Ga hydrothermal vent precipitates from Barberton, South Africa. Much later in the geologic record, likely starting in 1.73 Ga, preserved molecular compounds of biologic origin are indicative of aerobic life. Therefore, the earliest time for the origin of life on Earth is at most 3.5 billion years ago, possibly as early as 4.1 billion years ago — not long after the oceans formed 4.5 billion years ago and after the formation of the Earth 4.54 billion years ago.

<span class="mw-page-title-main">Eoarchean geology</span> Study of the oldest crustal fragments on Earth

Eoarchean geology is the study of the oldest preserved crustal fragments of Earth during the Eoarchean era from 4.031 to 3.6 billion years ago. Major well-preserved rock units dated to this era are known from three localities, the Isua Greenstone Belt in Southwest Greenland, the Acasta Gneiss in the Slave Craton in Canada, and the Nuvvuagittuq Greenstone Belt in the eastern coast of Hudson Bay in Quebec. From the dating of rocks in these three regions, scientists suggest that the beginning of plate tectonics could have started as far back as early as the Eoarchean.

<span class="mw-page-title-main">Hadean zircon</span> Oldest-surviving crustal material from the Earths earliest geological time period

Hadean zircon is the oldest-surviving crustal material from the Earth's earliest geological time period, the Hadean eon, about 4 billion years ago. Zircon is a mineral that is commonly used for radiometric dating because it is highly resistant to chemical changes and appears in the form of small crystals or grains in most igneous and metamorphic host rocks.

<span class="mw-page-title-main">Big Bertha (lunar sample)</span> First Moon rock of Earth origin, discovered by the crew of Apollo 14

Lunar Sample 14321, better known as "Big Bertha", is a lunar sample containing an embedded Earth-origin meteorite collected on the 1971 Apollo 14 mission. It was found in the Fra Mauro region of the Moon. Big Bertha is the first discovered meteorite from Earth, and the embedded meteorite portion is the oldest known Earth rock. At 8.998 kg (19.84 lb), this breccia rock is the third largest Moon sample returned during the Apollo program, behind Big Muley and Great Scott.

<span class="mw-page-title-main">Eastern Block of the North China Craton</span>

The Eastern Block of the North China Craton is one of the Earth's oldest pieces of continent. It is separated from the Western Block by the Trans-North China Orogen. It is situated in northeastern China and North Korea. The Block contains rock exposures older than 2.5 billion years. It serves as an ideal place to study how the crust was formed in the past and the related tectonic settings.

References

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  3. 1 2 Discovery of world's oldest rocks challenged
  4. 1 2 Universities Space Research Association (USRA) (24 January 2019). "Earth's Oldest Rock Found on the Moon". NASA . Retrieved 25 January 2019.
  5. ↑ Lyons, Suzannah (13 January 2020). "Grains of stardust found in meteorite that landed in Victoria". ABC News (Australia) - Science.
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  10. ↑ Mutanen, Tapani; Huhma, Hannu (2003). "The 3.5 Ga Siurua trondhjemite gneiss in the Archaean Pudasjärvi Granulite Belt, northern Finland" (PDF). Bulletin of the Geological Society of Finland. 75 (1–2): 51–68. doi:10.17741/bgsf/75.1-2.004.
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  12. ↑ McGill University press release Closed Access logo transparent.svg
  13. ↑ Oldest rocks on Earth found
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  15. ↑ 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.
  16. ↑ Newswise: Ancient Mineral Shows Early Earth Climate Tough on Continents. Retrieved June 15, 2008.
  17. ↑ Lapen, T. J.; et al. (2010). "A Younger Age for ALH84001 and Its Geochemical Link to Shergottite Sources in Mars". Science . 328 (5976): 347–351. Bibcode:2010Sci...328..347L. doi:10.1126/science.1185395. PMID   20395507. S2CID   17601709.
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