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.

The oldest dated rocks on Earth are of several different types.

1. There are early rocks recovered from the Moon. This is relevant because the Moon was once part of the Earth: see giant impact hypothesis.[1][2] During Apollo 16, Lunar sample 67215, dated at 4.46 billion years, was brought back.[3] Lunar sample 67215 is the oldest known rock on Earth, even though it came from the Moon.

2. The oldest material of terrestrial origin that has been dated is a zircon mineral 4.404 ±0.008 billion years old. It was in the Jack Hills of Western Australia.[4] The oldest consistently-dated zircon is closer to 4.35 billion years ago.[5]

3. The oldest rock formation on Earth may be the Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada. It is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed by glacial action. Again it was dated by analysis of zircons in the rocks.[6]

References[change | change source]

  1. Freeman, David (2013). "How old is the Moon? 100 million years younger than once thought, new research suggests". The Huffington Post. Retrieved 2013-09-25.
  2. Soderman. "Evidence for Moon-forming impact found inside meteorites". NASA-SSERVI. Retrieved 7 July 2016.
  3. Norman M.D. et al 2003. Chronology, geochemistry, and petrology of a ferroan noritic anorthosite clast from Descartes breccia 67215: Clues to the age, origin, structure, and impact history of the lunar crust. Meteoritics and Planetary Science 38, pp. 645–61. Summary
  4. Wilde, Simon A. et al 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature Geoscience
  5. Wilde S.A. et al 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature 409, pp. 175–78. http://www.geology.wisc.edu/%7Evalley/zircons/Wilde2001Nature.pdf
  6. Bowring, Samuel A.; Williams, Ian S. (1999). "Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada". Contributions to Mineralogy and Petrology 134: 3. doi:10.1007/s004100050465.