Angrite

Source: Wikipedia, the free encyclopedia.
Angrite
— 
Stony meteorite
TypeAchondrite
SubgroupsQuenched Plutonic
3819 Robinson or Mercury
Total known specimens30+
Slice of plutonic angrite NWA 2999

Angrites are a rare group of

igneous rocks, with crystallization ages of around 4.56 billion years. Angrites are subdivided into two main groups, the quenched and plutonic angrites. The quenched angrites cooled rapidly upon the surface of the angrite parent body (APB), whereas the plutonic angrites cooled slower, deeper in the crust. The APB is thought to have been a similar size to the asteroid 4 Vesta
.

Origin

Angrite meteorites are distinct from other meteoritic groups based on their oxygen isotopic compositions.[1] Based on their Mn-Fe ratios in pyroxene and other isotopic compositions, the source of angrites is constrained to the inner Solar System. However, recent studies have suggested that the APB experienced mixing of multiple sources during its history.[2]

By comparing the

3819 Robinson. Other scientists have suggested that angrites could represent ejecta from Mercury, however later work has cast significant doubt upon these claims.[3]

Based on the lack of an asteroid matching the spectra of angrite meteorites it is thought that the APB was catastrophically disrupted and subsequently destroyed.

Notable meteorites

There are currently over 30 meteorites classified as angrites. The type specimen, the Angra dos Reis meteorite, was an observed fall in 1869 and weighed 1.5 kilograms (3.3 lb). Most of it has been lost over time; the largest remaining piece, weighing 101 grams, is kept at the Museum of Natural History in Rio de Janeiro.[4]

NWA 10463 has been suggested to represent an intermediate stage between the quenched and plutonic angrite meteorites. [5]

NWA 8535 has been suggested to represent a Dunite. [6]

Asuka-12209; Asuka-88371 and NWA 12320 demonstrate an oxygen isotopic disequilibrium indicative of planetary mixing. [2]

See also

External links

References

  1. ^ Rider-Stokes, Ben (2021). "REVISING THE ANGRITE FRACTIONATION LINE: NEW INSIGHTS FROM HIGH-PRECISION OXYGEN ISOTOPE STUDIES" (PDF). Annual Meeting of the Meteoritics Society. 6071: 1.
  2. ^ a b Rider-Stokes, Ben (2022). "Mixing in the early Solar System as evidenced by the quenched angrite meteorites" (PDF). 53rd Lunar and Planetary Science Conference. 1420: 2.
  3. Bibcode:2005AGUFM.P51A0898I
    .
  4. ISBN 978-0521663038
    .
  5. Bibcode:2017LPICo1987.6313S
    .
  6. Bibcode:2015LPI....46.2681A
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Angrite&oldid=1167400634"