Popigai impact structure
Landsat image of Popigai crater
Impact crater/structure
ConfidenceConfirmed
Diameter90 km (56 mi)
Age35.7 ± 0.2 Ma
Late Eocene
ExposedYes
DrilledYes
Bolide typeH chondrite
Location
Coordinates71°39′N 111°11′E / 71.650°N 111.183°E / 71.650; 111.183
CountryRussia
StateKrasnoyarsk
Popigai impact structure is located in Russia
Popigai impact structure
Location of the crater in Russia
Popigai crater in April 1967

The Popigai impact structure is the eroded remnant of an impact crater in northern Siberia, Russia. It is tied with the Manicouagan structure as the fourth largest verified impact structure on Earth.[1][2] A large bolide impact created the 100-kilometre (62 mi) diameter crater approximately 35 million years ago during the late Eocene epoch (Priabonian stage).[3][4] It might be linked to the Eocene–Oligocene extinction event.[5]

The structure is 300 km (190 mi) east from the outpost of Khatanga and 880 km (550 mi) northeast of the city of Norilsk, NNE of the Anabar Plateau. It is designated by UNESCO as a Geopark, a site of special geological heritage.[6] There is a small possibility that the Popigai impact crater may have formed simultaneously with the approximately 35-million-year-old Chesapeake Bay and Toms Canyon impact craters.[3]

For decades, the Popigai impact structure has fascinated paleontologists and geologists, but the entire area was completely off limits because of the diamonds found there. However, a major investigatory expedition was undertaken in 1997, which greatly advanced understanding of the structure.[6] The impactor is suggested to have been a H chondrite asteroid based on ejecta layers from Italy, with the impactor thought to have been several kilometeres in diameter.[7]

The shock pressures from the impact instantaneously transformed graphite in the ground into diamonds within a 13.6 km (8.5 mi) radius of the impact point. These diamonds are usually 0.5 to 2 mm (0.020 to 0.079 in) in diameter, though a few exceptional specimens are 10 mm (0.39 in) in size. The diamonds inherited the tabular shape of the original graphite grains and also the original crystals' delicate striations.[6]

Diamond deposits

Popigai diamonds are about 1 mm in size and consist of nanodiamond agglomerates.[8]

Most modern industrial diamonds are produced synthetically. The diamond deposits at Popigai have not been mined because of the remote location and lack of infrastructure, and are unlikely to be competitive with synthetic diamonds.[9] Many of the diamonds at Popigai contain crystalline lonsdaleite, an allotrope of carbon that has a hexagonal lattice.[10] Pure, laboratory-created lonsdaleite is up to 58% harder than ordinary diamonds.[11][9] These types of diamonds are known as "impact diamonds" because they are thought to be produced when a meteorite strikes a graphite deposit at high velocity.[10] They may have industrial uses but are unsuitable as gems.[12]

Additionally, carbon polymorphs, a combination of diamond and lonsdaleite even harder than pure lonsdaleite, have been discovered in the crater.[13][14]

See also

References

  1. ^ "Popigai". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2017-10-09.
  2. ^ Masaitis, Victor L. (2003). Popigai Crater: General Geology. Springer. pp. 81–85. ISBN 978-3-540-43517-4.
  3. ^ a b Deutsch, Alexander; Christian Koeberl (2006). "Establishing the link between the Chesapeake Bay impact structure and the North American tektite strewn field: The Sr-Nd isotopic evidence". Meteoritics & Planetary Science. 41 (5): 689–703. Bibcode:2006M&PS...41..689D. doi:10.1111/j.1945-5100.2006.tb00985.x.
  4. ^ Armstrong, Richard; S. Vishnevsky; C. Koeberl (2003). U-Pb Analysis of zircons from the Popigai impact structure, Russia: First Results. Springer. pp. 99–116. ISBN 978-3-540-43517-4.
  5. ^ "Russia's Popigai Meteor Crash Linked to Mass Extinction". Live Science. June 13, 2014.
  6. ^ a b c Deutsch, Alexander; V.L. Masaitis; F. Langenhorst; R.A.F. Grieve (2000). "Popigai, Siberia—well preserved giant impact structure, national treasury, and world's geological heritage". Episodes. 23 (1): 3–12. doi:10.18814/epiiugs/2000/v23i1/002.
  7. ^ Schmitz, Birger; Boschi, Samuele; Cronholm, Anders; Heck, Philipp R.; Monechi, Simonetta; Montanari, Alessandro; Terfelt, Fredrik (September 2015). "Fragments of Late Eocene Earth-impacting asteroids linked to disturbance of asteroid belt". Earth and Planetary Science Letters. 425: 77–83. doi:10.1016/j.epsl.2015.05.041.
  8. ^ Ohfuji, Hiroaki; Irifune, Tetsuo; Litasov, Konstantin D.; Yamashita, Tomoharu; Isobe, Futoshi; Afanasiev, Valentin P.; Pokhilenko, Nikolai P. (2015). "Natural occurrence of pure nano-polycrystalline diamond from impact crater". Scientific Reports. 5: 14702. Bibcode:2015NatSR...514702O. doi:10.1038/srep14702. PMC 4589680. PMID 26424384.
  9. ^ a b "Diamonds Beneath the Popigai Crater -- Northern Russia". geology.com. 23 September 2012. Retrieved 24 September 2012.
  10. ^ a b "Russia declassifies deposit of impact diamonds". ITAR-TASS. 17 September 2012. Archived from the original on 20 September 2012. Retrieved 17 September 2012.
  11. ^ Pan, Zicheng; Sun, Hong; Zhang, Yi & Chen, Changfeng (2009). "Harder than Diamond: Superior Indentation Strength of Wurtzite BN and Lonsdaleite". Physical Review Letters. 102 (5): 055503. Bibcode:2009PhRvL.102e5503P. doi:10.1103/PhysRevLett.102.055503. PMID 19257519.
  12. ^ Pros and cons of extraterrestrial diamonds Archived 2014-12-22 at the Wayback Machine, from "Rough&Polished–information and analytics on diamond and jewellery markets."
  13. ^ El Goresy, Ahmed; Dubrovinsky, Leonid S; Gillet, Philippe; Mostefaoui, Smail; Graup, Günther; Drakopoulos, Michael; Simionovici, Alexandre S; Swamy, Varghese; Masaitis, Victor L (2003). "A new natural, super-hard, transparent polymorph of carbon from the Popigai impact crater, Russia". Comptes Rendus Geoscience. 335 (12): 889. Bibcode:2003CRGeo.335..889E. doi:10.1016/j.crte.2003.07.001.
  14. ^ Baek, Woohyeon; Gromilov, Sergey A.; Kuklin, Artem V.; Kovaleva, Evgenia A.; Fedorov, Alexandr S.; Sukhikh, Alexander S.; Hanfland, Michael; Pomogaev, Vladimir A.; Melchakova, Iuliia A.; Avramov, Paul V.; Yusenko, Kirill V. (2019-03-13). "Unique Nanomechanical Properties of Diamond–Lonsdaleite Biphases: Combined Experimental and Theoretical Consideration of Popigai Impact Diamonds". Nano Letters. 19 (3): 1570–1576. Bibcode:2019NanoL..19.1570B. doi:10.1021/acs.nanolett.8b04421. ISSN 1530-6984. PMID 30735045. S2CID 73443676.

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