IVB meteorite
IVB meteorites | |
---|---|
— Magmatic | |
Subgroups |
|
Parent body | IVB |
Composition | Meteoric iron (kamacite, taenite & tetrataenite); low in volatile elements, high in nickel & refractory elements |
Total known specimens | 14 |
IVB meteorites are a group of
Description
The IVB meteorites are composed of meteoric iron (kamacite, taenite and tetrataenite). The chemical composition is low in volatile elements and high in nickel and refractory elements. Although most IVB meteorites are ataxites ("without structure"), they do show microscopic Widmanstätten patterns. The lamellae are smaller than 20 µm wide and lie in a matrix of plessite.[3] The Tlacotepec meteorite is an octahedrite, making a notable exception, as most IVBs are ataxites.[4]
Classification
Iron meteorites were originally divided into four groups designated by Roman numerals (I, II, III, IV). When more chemical data became available some groups were split. Group IV was split into IVA and IVB meteorites.[5] The chemical classification is based on diagrams that plot nickel content against different trace elements (e.g. gallium, germanium and iridium). The different iron meteorite groups appear as data point clusters.[1][6]
Parent body
IVB meteorites formed the core of a parent body that was later destroyed, some of the fragments falling on Earth as meteorites.[3] Modeling the IVB parent body has to take into account the extreme chemical composition, especially the depletion of volatile elements (gallium, germanium) and the enrichment in refractory elements (iridium) compared to other iron meteorites.[2]
The history of the parent body has been reconstructed in detail. The IVB parent body will have formed from material that condensed at the highest temperatures while the solar nebula cooled off. The enrichment in refractory elements was caused by less than 10 % of the condensible material going into the parent body.
Notable specimens
As of December 2012, 14 specimens of IVB meteorites are known.[11] A notable specimen is the Hoba meteorite, the largest known intact meteorite. There has never been an observed fall of an IVB meteorite.[11]
See also
References
- ^ ISBN 978-0816525621. Retrieved 15 December 2012.
- ^ .
- ^ .
- ^ "The Catalogue of Meteorites". nhm.ac.uk.
- ISBN 978-0521587518.
- .
- ^ Bland, P. A.; F. J. Ciesla (2010). "The Impact of Nebular Evolution on Volatile Depletion Trends Observed in Differentiated Objects" (PDF). 41st Lunar and Planetary Science Conference. Retrieved 23 December 2012.
- .
- .
- .
- ^ a b "Meteoritical Bulletin Database". Meteoritical Society. Retrieved 17 December 2012.