Popigai impact structure explained

Popigai impact structure
Map:Russia
Coordinates:71.65°N 122°W
Confidence:Confirmed
Diameter:90km (60miles)
Age:35.7 ± 0.2 Ma
Late Eocene
Exposed:Yes
Drilled:Yes
Bolide:H chondrite
Country:Russia
State:Krasnoyarsk

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 100km (100miles) 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 300km (200miles) east from the outpost of Khatanga and 880km (550miles) 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 13.6km (08.5miles) radius of the impact point. These diamonds are usually 0.5to in diameter, though a few exceptional specimens are 10mm in size. The diamonds inherited the tabular shape of the original graphite grains and also the original crystals' delicate striations.[6]

Diamond deposits

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.[8] Many of the diamonds at Popigai contain crystalline lonsdaleite, an allotrope of carbon that has a hexagonal lattice.[9] Pure, laboratory-created lonsdaleite is up to 58% harder than ordinary diamonds.[10] 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.[9] They may have industrial uses but are unsuitable as gems.[11]

Additionally, carbon polymorphs, a combination of diamond and lonsdaleite even harder than pure lonsdaleite, have been discovered in the crater.[12] [13]

See also

External links

Notes and References

  1. Popigai . html . 2017-10-09.
  2. Book: Masaitis , Victor L. . Springer. 81–85. Popigai Crater: General Geology. 2003. 978-3-540-43517-4.
  3. 10.1111/j.1945-5100.2006.tb00985.x . 41 . 689–703 . Deutsch . Alexander . Christian Koeberl . Establishing the link between the Chesapeake Bay impact structure and the North American tektite strewn field: The Sr-Nd isotopic evidence . Meteoritics & Planetary Science . 2006 . 5 . 2006M&PS...41..689D. free .
  4. Book: Armstrong , Richard . Springer. 99–116. S. Vishnevsky . C. Koeberl. U-Pb Analysis of zircons from the Popigai impact structure, Russia: First Results. 2003. 978-3-540-43517-4.
  5. Web site: Russia's Popigai Meteor Crash Linked to Mass Extinction. . June 13, 2014.
  6. 23 . 3–12 . Deutsch . Alexander . V.L. Masaitis . F. Langenhorst . R.A.F. Grieve . Popigai, Siberia—well preserved giant impact structure, national treasury, and world's geological heritage . Episodes . 2000 . 1. 10.18814/epiiugs/2000/v23i1/002 . free .
  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 . en . 425 . 77–83 . 10.1016/j.epsl.2015.05.041 . free. 2015E&PSL.425...77S .
  8. News: Diamonds Beneath the Popigai Crater -- Northern Russia. 24 September 2012. 23 September 2012. geology.com.
  9. News: Russia declassifies deposit of impact diamonds. ITAR-TASS. 17 September 2012. 17 September 2012. https://web.archive.org/web/20120920221513/http://pda.itar-tass.com/en/c154/521362.html. 20 September 2012. dead.
  10. Pan, Zicheng . Sun, Hong . Zhang, Yi . Chen, Changfeng . amp . Harder than Diamond: Superior Indentation Strength of Wurtzite BN and Lonsdaleite . Physical Review Letters. 5. 055503. 2009 . 10.1103/PhysRevLett.102.055503. 102. 19257519. 2009PhRvL.102e5503P.
  11. http://www.rough-polished.com/en/digest/68330.html Pros and cons of extraterrestrial diamonds
  12. 10.1016/j.crte.2003.07.001. A new natural, super-hard, transparent polymorph of carbon from the Popigai impact crater, Russia. Comptes Rendus Geoscience. 335. 12. 889. 2003. El Goresy. Ahmed. Dubrovinsky. Leonid S. Gillet. Philippe. Mostefaoui. Smail. Graup. Günther. Drakopoulos. Michael. Simionovici. Alexandre S. Swamy. Varghese. Masaitis. Victor L. 2003CRGeo.335..889E.
  13. 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. 10.1021/acs.nanolett.8b04421. 30735045. 2019NanoL..19.1570B. 73443676 . 1530-6984.

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