Two children are sitting within the corrosion grooves of the Willamette meteorite. Considerable mass has been lost to terrestrial weathering.
Two children are sitting within the corrosion grooves of the Willamette meteorite. Considerable mass has been lost to terrestrial weathering.
A Sikhote-Alin meteorite with visible rust.
A Sikhote-Alin meteorite with visible rust.

Meteorite weathering is the terrestrial alteration of a meteorite. Most meteorites date from the oldest times in the Solar System and are by far the oldest material available on our planet. Despite their age, they are vulnerable to the terrestrial environment. Water, chlorine and oxygen attack meteorites as soon as they reach the ground.

Weathering scales

In order to quantify the degree of alteration that a meteorite experienced, several qualitative weathering indices have been applied to antarctic and desert samples.[1]

The most known weathering scale is based upon the effects seen in polished thin sections of chondritic meteorites and it ranges from W0 (pristine) to W6 (heavy alteration). It was proposed by Jull A. J. T. et al.[2] (1991) and updated by Wlotzka[3][4](1993) and Al-Kathiri et al.[5](2005).

The Meteorite Working Group at the Johnson Space Center uses weathering categories A B, C and E to denote the alteration of antarctic meteorites.[1] Their official definitions are:[6]

See also

References

  1. ^ a b P. A. Bland, M. E. Zolensky, G. K. Benedix, M. A. Sephton. "Weathering of Chondritic Meteorites"
  2. ^ Jull, A. J. T.; Wlotzka, F.; Donahue, D. J. (1991). "Terrestrial Ages and Petrologic Description of Roosevelt County Meteorites". Abstracts of the Lunar and Planetary Science Conference. 22: 667. Bibcode:1991LPI....22..667J.
  3. ^ Wlotzka, F. (1993). "A Weathering Scale for the Ordinary Chondrites". Meteoritics. 28: 460. Bibcode:1993Metic..28Q.460W.
  4. ^ Wlotzka, F.; Jull, A. J. T.; Donahue, D. J. (1995). "Carbon-14 Terrestrial Ages of Meteorites from Acfer, Algeria". Workshop on Meteorites from Cold and Hot Deserts: 72. Bibcode:1995mfch.work...72W.
  5. ^ Al-Kathiri, A.; Hofmann, B. A.; Jull, A. J. T.; Gnos, E. (2005). "Weathering of meteorites from Oman: Correlation of chemical and mineralogical weathering proxies with14C terrestrial ages and the influence of soil chemistry". Meteoritics & Planetary Science. 40 (8): 1215–1239. Bibcode:2005M&PS...40.1215A. doi:10.1111/j.1945-5100.2005.tb00185.x.
  6. ^ "Meteorite Weathering Categories". curator.jsc.nasa.gov.