Shock-induced deformation of Shergottites: Shock-pressures and perturbations of magmatic ages on Mars

Goresy, A. El; Gillet, Ph.; Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Seiji; Beck, Pierre; Montagnac, Gilles

doi:10.1016/j.gca.2012.10.002

Cited by 84 publications

(118 citation statements)

References 60 publications

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“…40 Ar-39 Ar radio-isotopic age is sensitive to temperature. Several previous studies show evidences that a dynamic event can modify 40 Ar-39 Ar radio-isotopic ages [34][35][36][37][38] . 40 Ar-39 Ar radio-isotopic spectrum of NWA 4734 shows a broad 'plateau' at B2.7 Ga 33 , implying that the 40 Ar- 39 Ar system was completely reset.…”

Section: Discussionmentioning

confidence: 97%

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Discovery of seifertite in a shocked lunar meteorite

et al. 2013

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Many craters and thick regoliths of the moon imply that it has experienced heavy meteorite bombardments. Although the existence of a high-pressure polymorph is a stark evidence for a dynamic event, few high-pressure polymorphs are found in a lunar sample. a-PbO 2 -type silica (seifertite) is an ultrahigh-pressure polymorph of silica, and is found only in a heavily shocked Martian meteorite. Here we show evidence for seifertite in a shocked lunar meteorite, Northwest Africa 4734. Cristobalite transforms to seifertite by high-pressure and -temperature condition induced by a dynamic event. Considering radio-isotopic ages determined previously, the dynamic event formed seifertite on the moon, accompanying the complete resetting of radio-isotopic ages, is B2.7 Ga ago. Our finding allows us to infer that such intense planetary collisions occurred on the moon until at least B2.7 Ga ago.

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Section: Discussionmentioning

confidence: 97%

“…Most of the maskelynite in NWA 4734 has smooth surfaces without fractures or planar defects. Feldspar was heated and subsequently melted, finally became amorphous by quenching during a dynamic event 38 , thus leading to degassing of argon. The bulk modulus of feldspar is smaller than those of olivine and pyroxene, for example, Matsui 41 .…”

Section: Discussionmentioning

confidence: 99%

Discovery of seifertite in a shocked lunar meteorite

et al. 2013

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“…These observations suggest a recorded shock pressure higher than ~10 GPa (Langenhorst and Deutsch, 2012). On the other hand, no melt pockets or veins have been observed, all feldspar grains are plagioclase without any evidence for maskelynite, diaplectic glass or planar deformation features (PDFs), suggesting shock pressure lower than ~20 GPa (Langenhorst and Deutsch, 2012;Gillet and El Goresy, 2013).…”

Section: The Bunburra Rockhole Anomalous Basaltic Achondritementioning

confidence: 75%

“…10-20 GPa. Such a range of shock pressure corresponds to an equivalent temperature of ~250°C on the Hugoniot curve (a theoretical P-T curve which constrains the temperature value for any given pressure; Langenhorst and Deutsch, 2012) of basalt (Gillet and El Goresy, 2013). Thus, the meteorite could be classified as shock stage S3.…”

Section: The Bunburra Rockhole Anomalous Basaltic Achondritementioning

confidence: 99%

“…Neither the P-T conditions were met to form diaplectic glass (P= 25-35 GPa ≈ 600 °C for basalt). Nevertheless undulatory features and cracks were observed suggesting temperatures around 200-300°C and pressures of 10-20 GPa (French, 1998;Langenhorst and Deutsch, 2012;Gillet and El Goresy, 2013). Therefore, the first hypothesis would require moderately elevated temperatures sustained for long enough to fully reset both plagioclase and pyroxene crystals.…”

Section: Diffusion Modelsmentioning

confidence: 99%

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40Ar/39Ar impact ages and time–temperature argon diffusion history of the Bunburra Rockhole anomalous basaltic achondrite

Jourdan

Benedix

Eroğlu³

et al. 2014

Geochimica et Cosmochimica Acta

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Maskelynite formation via solid‐state transformation: Evidence of infrared and X‐ray anisotropy

et al. 2015

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We present the results of a combined study of shocked labradorite from the Lonar crater, India, using optical microscopy, micro-Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, high-energy X-ray total scattering experiments, and micro-Fourier transform infrared (micro-FTIR) spectroscopy. We show that maskelynite of shock class 2 is structurally more similar to fused glass than to crystalline plagioclase. However, there are slight but significant differences-preservation of original preimpact igneous zoning, anisotropy at infrared wavelengths, X-ray anisotropy, and preservation of some intermediate range order-which are all consistent with a solid-state transformation from plagioclase to maskelynite.

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Shock-induced deformation of Shergottites: Shock-pressures and perturbations of magmatic ages on Mars

Cited by 84 publications

References 60 publications

Discovery of seifertite in a shocked lunar meteorite

Discovery of seifertite in a shocked lunar meteorite

40Ar/39Ar impact ages and time–temperature argon diffusion history of the Bunburra Rockhole anomalous basaltic achondrite

Maskelynite formation via solid‐state transformation: Evidence of infrared and X‐ray anisotropy

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