Ringwoodite microstructures in L-chondrite NWA 5011: implications for transformation mechanism and source region in L parent body

Nagy, Szabolcs; Józsa, Sándor; Gyollai, I.; Bendő, Zsolt; Stehlik, H.

doi:10.1556/ceugeol.54.2011.3.2

Cited by 8 publications

(4 citation statements)

References 18 publications

(18 reference statements)

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“…The samples analysed in the present study have a deep royal blue colouration, typical of iron-bearing hydrous ringwoodites. The origin of blue colouration in ringwoodite and other high-pressure ferromagnesian silicates is currently uncertain, having been attributed to light scattering (e.g., Lingemann and Stöffler, 1998;Nagy et al 2011), or intervalence charge transfer (e.g., Taran et al 2009). Iron-bearing magnesian ringwoodite can vary in colour from colourless through pale green to deep blue/purple.…”

Section: Discussionmentioning

confidence: 99%

Incorporation of tetrahedral ferric iron into hydrous ringwoodite

Thomson

Piltz

Crichton

et al. 2021

American Mineralogist

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Hydrous Fo 91 ringwoodite crystals were synthesised at 20 GPa and high-temperature conditions using a multi-anvil press. Recovered crystals were analysed using electron microprobe analysis, Raman spectroscopy, infrared spectroscopy, synchrotron Mössbauer spectroscopy, single-crystal X-ray diffraction and single-crystal Laue neutron diffraction, to carefully characterise the chemistry and crystallography of the samples. Analysis of the combined datasets provides evidence for the presence of tetrahedrally coordinated ferric iron and multiple hydrogen incorporation mechanisms within these blue-coloured iron-bearing ringwoodite crystals. Tetrahedral ferric iron is coupled with cation disorder of silicon onto the octahedrally coordinated site. Cation disorder in mantle ringwoodite minerals may be promoted in the presence of water, which could have implications for current models of seismic velocities within the transition zone. Additionally, the presence of tetrahedrally coordinated ferric iron may cause the blue colour of many ringwoodite, and other high-pressure, crystals. This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Discussionmentioning

confidence: 99%

Incorporation of tetrahedral ferric iron into hydrous ringwoodite

Thomson

Piltz

Crichton

et al. 2021

American Mineralogist

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“…In order to confirm their hypothesis, more investigation should be conducted on the meteoritic Rw, which represents the best natural specimen for studying high-P structural features, including the Mg-Si order-disorder state, due to its having much larger quench rates. Rw of various colors has been documented in many meteorites, including L ordinary chondrites [108][109][110][111][112], LL ordinary chondrites [14,26], and Martian meteorites like the shergottites [32,34,37]. If the relationship among the color, composition, inverse magnitude, P and T can be adequately quantified, a fine scale for accurately estimating the shock P-T conditions may be derived, which may serve well the theoretical evolution models of the early solar system.…”

Section: Discussionmentioning

confidence: 99%

Si-Disordering in MgAl2O4-Spinel under High P-T Conditions, with Implications for Si-Mg Disorder in Mg2SiO4-Ringwoodite

Liu

Bao

et al. 2018

Minerals

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A series of Si-bearing MgAl 2 O 4 -spinels were synthesized at 1500-1650 • C and 3-6 GPa. These spinels had SiO 2 contents of up to~1.03 wt % and showed a substitution mechanism of Si 4+ + Mg 2+ = 2Al 3+ . Unpolarized Raman spectra were collected from polished single grains, and displayed a set of well-defined Raman peaks at~610, 823, 856 and 968 cm −1 that had not been observed before. Aided by the Raman features of natural Si-free MgAl 2 O 4 -spinel, synthetic Si-free MgAl 2 O 4 -spinel, natural low quartz, synthetic coesite, synthetic stishovite and synthetic forsterite, we infer that these Raman peaks should belong to the SiO 4 groups. The relations between the Raman intensities and SiO 2 contents of the Si-bearing MgAl 2 O 4 -spinels suggest that under some P-T conditions, some Si must adopt the M-site. Unlike the SiO 4 groups with very intense Raman signals, the SiO 6 groups are largely Raman-inactive. We further found that the Si cations primarily appear on the T-site at P-T conditions ≤~3-4 GPa and 1500 • C, but attain a random distribution between the T-site and M-site at P-T conditions ≥~5-6 GPa and 1630-1650 • C. This Si-disordering process observed for the Si-bearing MgAl 2 O 4 -spinels suggests that similar Si-disordering might happen to the (Mg,Fe) 2 SiO 4 -spinels (ringwoodite), the major phase in the lower part of the mantle transition zone of the Earth and the benchmark mineral for the very strong shock stage experienced by extraterrestrial materials. The likely consequences have been explored.

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“…ЛИТАСОВ, БАДюКОВ ные обломки первичных минералов, полностью преобразованных в высокобарические фазы (за исключением хромита). Текстура более крупных образцов метеорита NWA 5011 исследована в работе (Nagy et al, 2011), где отмечается, что максимальные размеры зерен оливина в зернистой матрице достигают 10 мм, а размер хондрул находится в пределах 0.5-4.0 см. Составы минералов хондрита NWA 5011 приведены в табл.…”

Section: Chrunclassified

Raman spectroscopy of high-pressure phases in shocked L6 chondrite NWA 5011

Litasov

Badyukov

2019

Геохимия

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In the paper we present results of studies of thick shock melt veins in NWA 5011 L6 chondrite. The veins contain a wide variety of high-pressure phases that correspond to contrast values of pressure-temperature parameters on equilibrium phase diagrams. Olivine was transformed to ringwoodite and wadsleyte, orthopyroxene to majorite, akimotoite, and bridgmanite glass, maskelenite is converted to jadeite (+SiO2) and lingunite, apatite to tuite, and chromite to the phase with the calcium ferrite (mCF-FeCr2O4) structure. ) The peak PT shock parameters for NWA 5011 seem highest among the ones for other shocked chondrites according to wide occurrence of lingunite and bridgmanite glass and are considerable higher than 25 GPa and 2500 K. Akimotoite crystals in a quenched matrix of shock melt veins were found for the first time. Probably, they initially crystallized as bridgmanite, since akimotoite is not a liquidus phase in related systems. Plagioclase-chromite aggregates have been established, which characterize the late stages of the shock process and are formed during successive crystallization from isolated pockets of the impact melt.

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Ringwoodite microstructures in L-chondrite NWA 5011: implications for transformation mechanism and source region in L parent body

Cited by 8 publications

References 18 publications

Incorporation of tetrahedral ferric iron into hydrous ringwoodite

Incorporation of tetrahedral ferric iron into hydrous ringwoodite

Si-Disordering in MgAl2O4-Spinel under High P-T Conditions, with Implications for Si-Mg Disorder in Mg2SiO4-Ringwoodite

Raman spectroscopy of high-pressure phases in shocked L6 chondrite NWA 5011

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