H/L chondrite LaPaz Icefield 031047 - A feather of Icarus?

Axel Wittmann, Jon M. Friedrich, Julianne Troiano, Robert J. Macke, Daniel T. Britt, Timothy Swindle, John R. Weirich, Douglas Rumble, Jeremie Lasue, David A. Kring

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Antarctic meteorite LAP 031047 is an ordinary chondrite composed of loosely consolidated chondritic fragments. Its petrography, oxygen isotopic composition and geochemical inventory are ambiguous and indicate an intermediate character between H and L chondrites. Petrographic indicators suggest LAP 031047 suffered a shock metamorphic overprint below ∼10 GPa, which did not destroy its unusually high porosity of ∼27 vol%. Metallographic textures in LAP 031047 indicate heating above ∼700. °C and subsequent cooling, which caused massive transformation of taenite to kamacite. The depletion of thermally labile trace elements, the crystallization of chondritic glass to microcrystalline plagioclase of unusual composition, and the occurrence of coarsely crystallized chondrule fragments is further evidence for post-metamorphic heating to ∼700-750. °C. However, this heating event had a transient character because olivine and low-Ca pyroxene did not equilibrate. Nearly complete degassing up to very high temperatures is indicated by the thorough resetting of LAP 031047's Ar-Ar reservoir ∼100 ± 55 Ma ago. A noble gas cosmic-ray exposure age indicates it was reduced to a meter-size fragment at <0.5. Ma. In light of the fact that shock heating cannot account for the thermal history of LAP 031047 in its entirety, we test the hypothesis that this meteorite belonged to the near-surface of an Aten or Apollo asteroid that underwent heating during orbital passages close to the Sun.

Original languageEnglish (US)
Pages (from-to)6140-6159
Number of pages20
JournalGeochimica et Cosmochimica Acta
Volume75
Issue number20
DOIs
StatePublished - Oct 15 2011

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feather
chondrite
heating
Heating
Meteorites
meteorite
taenite
Petrography
Noble Gases
Asteroids
ordinary chondrite
resetting
chondrule
Cosmic rays
noble gas
Degassing
Trace Elements
degassing
Crystallization
petrography

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Wittmann, A., Friedrich, J. M., Troiano, J., Macke, R. J., Britt, D. T., Swindle, T., ... Kring, D. A. (2011). H/L chondrite LaPaz Icefield 031047 - A feather of Icarus? Geochimica et Cosmochimica Acta, 75(20), 6140-6159. https://doi.org/10.1016/j.gca.2011.07.037

H/L chondrite LaPaz Icefield 031047 - A feather of Icarus? / Wittmann, Axel; Friedrich, Jon M.; Troiano, Julianne; Macke, Robert J.; Britt, Daniel T.; Swindle, Timothy; Weirich, John R.; Rumble, Douglas; Lasue, Jeremie; Kring, David A.

In: Geochimica et Cosmochimica Acta, Vol. 75, No. 20, 15.10.2011, p. 6140-6159.

Research output: Contribution to journalArticle

Wittmann, A, Friedrich, JM, Troiano, J, Macke, RJ, Britt, DT, Swindle, T, Weirich, JR, Rumble, D, Lasue, J & Kring, DA 2011, 'H/L chondrite LaPaz Icefield 031047 - A feather of Icarus?', Geochimica et Cosmochimica Acta, vol. 75, no. 20, pp. 6140-6159. https://doi.org/10.1016/j.gca.2011.07.037
Wittmann A, Friedrich JM, Troiano J, Macke RJ, Britt DT, Swindle T et al. H/L chondrite LaPaz Icefield 031047 - A feather of Icarus? Geochimica et Cosmochimica Acta. 2011 Oct 15;75(20):6140-6159. https://doi.org/10.1016/j.gca.2011.07.037
Wittmann, Axel ; Friedrich, Jon M. ; Troiano, Julianne ; Macke, Robert J. ; Britt, Daniel T. ; Swindle, Timothy ; Weirich, John R. ; Rumble, Douglas ; Lasue, Jeremie ; Kring, David A. / H/L chondrite LaPaz Icefield 031047 - A feather of Icarus?. In: Geochimica et Cosmochimica Acta. 2011 ; Vol. 75, No. 20. pp. 6140-6159.
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