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Jack Hills




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Location of the Jack Hills in Australia
Satellite image

The Jack Hills are a range of hills in Western Australia. They include the oldest material of terrestrial origin found on Earth. These are zircons which formed about 4.4 billion years ago (bya).[1] The oldest zircon with the most consistent date is closer to 4.35 bya.[2]

This zircon is part of a population of zircons in the metamorphosed conglomerate. They were deposited about 3.060 bya, which is the age of the youngest detrital zircon in the rock.

The zircons are used in research on the conditions on Earth in the Hadean eon.

Comparisons

We have samples of rock from the Moon which are older than these zircons. The "Genesis Rock", got from the Moon by astronauts in the Apollo 15 mission, has been dated at 4.46 billion years.[3] This is one of the oldest known rocks on Earth, though it originated on the Moon. During Apollo 16, older rocks were brought back.

The Allan Hills 84001 meteorite was blasted off from Mars by meteorite impact about 4.5 bya, and crystallised 4.091 bya. It arrived on Earth about 13,000 years ago. These figures were got by a number of radiometric dating techniques.[4][5]

References

  1. Simon A. Wilde et al 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 billion years ago. Nature Geoscience.
  2. 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, 175-178. [1]
  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, 645-661. Summary
  4. Nyquist L.E. et al 1999.. "Lunar meteorites and the lunar crustal SR and Nd isotopic compositions". Lunar and Planetary Science 27: 971.
  5. Borg, Lars et al (1999). "The age of the carbonates in Martian meteorite ALH84001". Science 286 (5437): 90–94. doi:10.1126/science.286.5437.90 . PMID 10506566 .