Estimating compositions of natural ringwoodite in the heavily shocked Grove Mountains 052049 meteorite from Raman spectra

Feng, Liang; Lin, Yangting; Hu, Sen; Xu, Lin; Miao, Bingkui

doi:10.2138/am.2011.3679

Cited by 38 publications

(43 citation statements)

References 38 publications

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“…Ringwoodite has been identified in Dhofar 1970 by its purple color in transmitted light and peak positions in the Raman spectrum matching the expected vibrational modes for this mineral (McMillan and Akaogi ; Feng et al. ). Ringwoodite occurs in two distinct settings–within the shock vein matrix and as bright, polycrystalline aggregates.…”

Section: Resultsmentioning

confidence: 97%

Mechanisms of ringwoodite formation in shocked meteorites: Evidence from L5 chondrite Dhofar 1970

Walton

McCarthy

2017

Meteorit & Planetary Scien

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The formation of the high‐pressure compositional equivalents of olivine and pyroxene has been well‐documented within and surrounding shock‐induced veins in chondritic meteorites, formed by crystallization from a liquid‐ or solid‐state phase transformation. Typically polycrystalline ringwoodite grains have a narrow range of compositions that overlap with those of their olivine precursors, whereas the formation of iron‐enriched ringwoodite has been documented from only a handful of meteorites. Here, we report backscattered electron images, quantitative wavelength‐dispersive spectrometry (WDS) analyses, qualitative WDS elemental X‐ray maps, and micro‐Raman spectra that reveal the presence of Fe‐rich ringwoodite (Fa44‐63) as fine‐grained (500 nm), polycrystalline rims on olivine (Fa24‐25) wall rock and as clasts engulfed by shock melt in a previously unstudied L5 chondrite, Dhofar 1970. Crystallization of majorite + magnesiowüstite in the vein interior and metastable mineral assemblages within 35 μm of the vein margin attest to rapid crystallization of a superheated shock melt (>2300 K) from 20─25 GPa to ambient pressure and temperature. The texture and composition of bright polycrystalline ringwoodite rims (Fa44‐63; MnO 0.01─0.08 wt%) surrounding dark polycrystalline olivine (Fa8‐14; MnO 0.56─0.65 wt%) implies a solid‐state transformation mechanism in which Fe was preferentially partitioned to ringwoodite. The spatial association between ringwoodite and shock melt suggests that the rapidly fluctuating thermal regimes experienced by chondritic minerals in contact with shock melt are necessary to both drive phase transformation but also to prevent back‐transformation.

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Section: Resultsmentioning

confidence: 97%

Mechanisms of ringwoodite formation in shocked meteorites: Evidence from L5 chondrite Dhofar 1970

Walton

McCarthy

2017

Meteorit & Planetary Scien

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“…These conditions are met during impact, which can readily generate shock waves greatly exceeding 5 km/s (the minimum velocity to eject rocks off Mars; Fritz et al, 2005). Ahrensites, described as natural γ-Fe 2 SiO 4 , have been previously reported from shock-melt pockets in ordinary chondrites (e.g., Xie et al, 2002;Feng et al, 2011) and ringwoodites have been described in a wide variety of ordinary chondrites, lunar rocks, and Martian meteorites (e.g., Binns, 1969;Zhang et al, 2011;Walton et al, 2014) but, in this Discussion, we focus on the formation and growth of ahrensite-ringwoodite in Tissint.…”

Section: Discussionmentioning

confidence: 99%

“…In some L5-L6 ordinary chondrites, Mg#s are low enough so that the phase being described is actually an ahrensite [i.e., Mg# < 50; Xie et al, 2002;Feng et al, 2011], with the mole % of Fe 2 SiO 4 as high as 98% in the L6 chondrite Umbarger (Xie et al, 2002). However, these descriptions did not lead to approval of a new mineral by the Commission on New Minerals, Nomenclature, and Classification (CNMNC).…”

Section: Introductionmentioning

confidence: 99%

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Tschauner

Beckett

et al. 2016

Geochimica et Cosmochimica Acta

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. where it forms through the transformation of the fayalite-rich rims of olivine megacrysts or Fe-rich microphenocrysts in contact with shock melt pockets. We report the first comprehensive set of crystallographic, spectroscopic, and quantitative chemical analysis of type ahrensite, and show that concentrations of ferric iron and inversion in the type material of this newly approved mineral are negligible. We also report the occurrence of nanocrystalline ringwoodite in strained olivine and establish correlations between grain size and distance from melt pockets. The ahrensite and ringwoodite crystals show no preferred orientation, consistent with random 2 nucleation and incoherent growth within a highly strained matrix of olivine. Grain sizes of ahrensite immediately adjacent to melt pockets are consistent with growth during a shock of moderate duration (1-10 ms).

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“…, with full solidsolution quantified by the Mg# (100Mg/(Mg1Fe)). A calibration of the shift of position of both DB1 and DB2 over the range Mg# 72-19 has been made using a shocked L5 chondrite meteorite 44 . There the Raman band positions were calibrated to compositional data determined by electron microprobe for 28 highquality measurements.…”

mentioning

confidence: 99%

Hydrous mantle transition zone indicated by ringwoodite included within diamond

Pearson

Brenker

Nestola

et al. 2014

Nature

667

371

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Estimating compositions of natural ringwoodite in the heavily shocked Grove Mountains 052049 meteorite from Raman spectra

Cited by 38 publications

References 38 publications

Mechanisms of ringwoodite formation in shocked meteorites: Evidence from L5 chondrite Dhofar 1970

Mechanisms of ringwoodite formation in shocked meteorites: Evidence from L5 chondrite Dhofar 1970

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Hydrous mantle transition zone indicated by ringwoodite included within diamond

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