IAB meteorite

IAB meteorites are a group of iron meteorites according to their overall composition and a group of primitive achondrites because of silicate inclusions that show a strong affinity to winonaites and chondrites.[1]

IAB meteorites
— Group —
Goose Lake Meteorite is a IAB meteorite in the sLL subgroup (low-Au, low-Ni)
TypeIron
Structural classificationHexahedrites, fine to coarse octahedrites, sometimes ataxites
ClassPrimitive achondrite
Subgroups
  • sLL
  • sLM (was IIIC)
  • sLH (was IIID)
  • sHL
  • sHH (includes Gay Gulch trio)
  • Udei Station grouplet
  • Pitts grouplet
  • Algarrabo duo
  • Mundrabilla duo
  • Britstown duo
  • NWA 468 duo
  • Twin City duo
  • Solo irons related to IAB
Parent bodyIAB
CompositionMeteoric iron (kamacite & taenite) & silicate inclusions

Description

The IAB meteorites are composed of meteoric iron (kamacite and taenite) and silicate inclusions. Structurally they can be hexahedrites, fine to coarse octahedrites, or even ataxites.[2] Most of them are octahedrite with medium to coarse taenite-lamella and distinct Widmanstätten patterning.[1]

The silicate inclusions are composed of low-Ca pyroxene, high-Ca pyroxene, olivine, plagioclase, troilite, graphite, different phosphates, meteoric iron and traces of daubréelite and chromite.[2] This composition is very similar to the composition of winonaites, and it is therefore argued that the two groups share the same parent body. There are also similarities with the IIICD meteorites,[3] but it is not yet clear whether they are also part of that parent body.[1]

Classification

The IAB group was created from the older IA and IB groups. Some authors also prefer to call it IAB complex.[3]

There are numerous subdivisions of the IAB group:[3]

  • IAB main group
  • sLL subgroup
  • sLM subgroup (originally IIIC)
  • sLH subgroup (originally IIID)
  • sHL subgroup
  • sHH subgroup (includes Gay Gulch trio)
  • Udei Station grouplet
  • Pitts grouplet
  • Algarrabo duo
  • Mundrabilla duo
  • Britstown duo
  • NWA 468 duo
  • Twin City duo
  • solo irons related to IAB
  • IAB related?

Parent body

Most scientists believe that the winonaites and the IAB meteorites share the same parent body. It is not yet fully understood whether the IIICD meteorites also belong to that body.[1]

Notable specimen

See also

References
  1. M. K. Weisberg; T. J. McCoy, A. N. Krot (2006). "Systematics and Evaluation of Meteorite Classification" (PDF). In D. S. Lauretta; H. Y. McSween, Jr. (eds.). Meteorites and the early solar system II. Tucson: University of Arizona Press. pp. 19–52. ISBN 978-0816525621. Retrieved 15 December 2012.
  2. Benedix, G. K.; T. J. McCoy; K. Keil; S. G. Love (2000). ") A petrologic study of the IAB iron meteorites: Constraints on the formation of the IAB-winonaite parent body" (PDF). Meteoritics and Planetary Science. 35 (6): 1127–1141. doi:10.1111/j.1945-5100.2000.tb01502.x. Archived from the original (PDF) on 1 March 2012. Retrieved 17 December 2012.
  3. Wasson, J.T; Kallemeyn, G.W (30 June 2002). "the IAB iron-meteorite complex: A group, five subgroups, numerous grouplets, closely related, mainly formed by crystal segregation in rapidly cooling melts". Geochimica et Cosmochimica Acta. 66 (13): 2445–2473. doi:10.1016/S0016-7037(02)00848-7. hdl:2060/20020080608.
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