Ringwoodite, Natural (Mg,Fe)2SiO4 Spinel in the Tenham Meteorite

Binns, R. A.; Davis, R. J.; Reed, S. J. B.

doi:10.1038/221943a0

Cited by 162 publications

(91 citation statements)

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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%

“…Ringwoodite is commonly observed in highly shocked meteorites from the Moon, Mars, and H and L ordinary chondrites (e.g., Binns et al, 1969;Kimura et al, 2003;Xie and Sharp, 2007;Zhang et al, 2011;Baziotis et al, 2013;Walton et al, 2014). 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).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

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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“…In highly shocked (S6) meteorites, both lithologies commonly contain high-pressure minerals, similar to those expected in the Earth's transition zone (410-660 km in depth) and lower mantle (>660 km in depth). These minerals include wadsleyite, ringwoodite, majorite, akimotoite, silicate perovskite, hollandite-structured plagioclase, post-stishovite SiO 2 polymorphs, and Fe 2 SiO 4 -spinel (Mason et al 1968;Binns et al 1969;Putnis and Price 1979;Price et al 1979;Price et al 1982;Sharp et al 1997;Tomioka and Fujino 1997;El Goresy et al 2000;Sharp et al 1999;Gillet et al 2000;Langenhorst and Poirier 2000;Xie et al 2002;Chen et al 2004a;Xie and Sharp 2004;Xie et al 2006). The high-pressure minerals in the shock-induced melt veins of meteorites not only provide high-pressure indicators for the shock event, they also provide natural samples of deep Earth materials that are not found in terrestrial rocks.…”

Section: Introductionmentioning

confidence: 99%

Estimating shock pressures based on high-pressure minerals in shock-induced melt veins of L chondrites

Xie

Sharp

Carli

2006

Meteoritics &Amp; Planetary Science

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Abstract-Here we report the transmission electron microscopy (TEM) observations of the mineral assemblages and textures in shock-induced melt veins from seven L chondrites of shock stages ranging from S3 to S6. The mineral assemblages combined with phase equilibrium data are used to constrain the crystallization pressures, which can be used to constrain shock pressure in some cases. Thick melt veins in the Tenham L6 chondrite contain majorite and magnesiowüstite in the center, and ringwoodite, akimotoite, vitrified silicate-perovskite, and majorite in the edge of the vein, indicating crystallization pressure of ~25 GPa. However, very thin melt veins (5-30 μm wide) in Tenham contain glass, olivine, clinopyroxene, and ringwoodite, suggesting crystallization during transient low-pressure excursions as the shock pressure equilibrated to a continuum level. Melt veins of Umbarger include ringwoodite, akimotoite, and clinopyroxene in the vein matrix, and Fe 2 SiO 4 -spinel and stishovite in SiO 2 -FeO-rich melt, indicating a crystallization pressure of ~18 GPa. The silicate melt veins in Roy contain majorite plus ringwoodite, indicating pressure of ~20 GPa. Melt veins of Ramsdorf and Nakhon Pathon contain olivine and clinoenstatite, indicating pressure of less than 15 GPa. Melt veins of Kunashak and La Lande include albite and olivine, indicating crystallization at less than 2.5 GPa. Based upon the assemblages observed, crystallization of shock veins can occur before, during, or after pressure release. When the assemblage consists of high-pressure minerals and that assemblage is constant across a larger melt vein or pocket, the crystallization pressure represents the equilibrium shock pressure.

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“…Such phases include lingunite (the highpressure polymorph of NaAlSi 3 O 8 in the hollandite structure) (1,2); stishovite and poststishovite silica phases (3)(4)(5); wadsleyite (6) and ringwoodite (7), the high-pressure polymorphs of (Mg,Fe) 2 SiO 4 in a spinelloid (wadsleyite) and the spinel structure (ringwoodite), respectively; and (Mg,Fe)SiO 3 in the garnet [majorite (8,9)], ilmenite [akimotoite (10)], and arguably the perovskite structure (11,12). Pressures of formation have been estimated from static synthesis experiments of such phases and range up to 26 GPa (12)(13)(14)(15)(16).…”

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confidence: 99%

Ultrafast growth of wadsleyite in shock-produced melts and its implications for early solar system impact processes

Tschauner

Asimow

Kostandova

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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We observed micrometer-sized grains of wadsleyite, a high-pressure phase of (Mg,Fe) 2SiO4, in the recovery products of a shock experiment. We infer these grains crystallized from shock-generated melt over a time interval of <1 s, the maximum time over which our experiment reached and sustained pressure sufficient to stabilize this phase. This rapid crystal growth rate (Ϸ1 m/s) suggests that, contrary to the conclusions of previous studies of the occurrence of high-pressure phases in shock-melt veins in strongly shocked meteorites, the growth of high-pressure phases from the melt during shock events is not diffusion-controlled. Another process, such as microturbulent transport, must be active in the crystal growth process. This result implies that the times necessary to crystallize the high-pressure phases in shocked meteorites may correspond to shock pressure durations achieved on impacts between objects 1-5 m in diameter and not, as previously inferred, Ϸ1-5 km in diameter. These results may also provide another pathway for syntheses, via shock recovery, of some high-value, high-pressure phases.meteorite ͉ recovery ͉ high-pressure phases ͉ planetesimal growth ͉ shock experiments A number of high-pressure silicate phases that stably occur only in the Earth's deep interior have documented natural occurrences, most commonly within shock-induced melt veins in L-and H-chondrites and Martian meteorites, notably the highly shocked (S6) Peace River, Tenham, Sixiangkou, and Yamato 791384 meteorites. Such phases include lingunite (the highpressure polymorph of NaAlSi 3 O 8 in the hollandite structure) (1, 2); stishovite and poststishovite silica phases (3-5); wadsleyite (6) and ringwoodite (7), the high-pressure polymorphs of (Mg,Fe) 2 SiO 4 in a spinelloid (wadsleyite) and the spinel structure (ringwoodite), respectively; and (Mg,Fe)SiO 3 in the garnet [majorite (8, 9)], ilmenite [akimotoite (10)], and arguably the perovskite structure (11,12). Pressures of formation have been estimated from static synthesis experiments of such phases and range up to 26 GPa (12-16). However, only stishovite has been recovered from shock experiments with very rapid quench and only in small amounts (17)(18)(19). None of the other dense silicate phases (wadsleyite, ringwoodite, majorite, lingunite, akimotoite, or perovskite) has been recovered from shock experiments conducted up to megabar pressures (20). These negative laboratory results in combination with observations of texture and paragenesis of high-pressure silicate polymorphs in meteorites have been used to infer the durations of shock-induced highpressure, high-temperature conditions to be on the order of seconds to minutes (15,(21)(22)(23)(24). In particular, this conclusion has been based on the grain size of these minerals (15), the width of lamellae within partly converted phases (21,22), and diffusion profiles of trace or major elements across phase boundaries (23, 24) between high-pressure minerals occurring within shockinduced melt veins of meteorites. Seconds-to minutes-lo...

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Ringwoodite, Natural (Mg,Fe)2SiO4 Spinel in the Tenham Meteorite

Cited by 162 publications

References 4 publications

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

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

Estimating shock pressures based on high-pressure minerals in shock-induced melt veins of L chondrites

Ultrafast growth of wadsleyite in shock-produced melts and its implications for early solar system impact processes

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