Electron microscopy of high-pressure phases synthesized from natural olivine in diamond anvil cell

Madon, M.; Guyot, François; Peyronneau, J.; Poirier, Jean‐Paul

doi:10.1007/bf00199551

Cited by 56 publications

(29 citation statements)

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“…The dissociation mechanisms of olivine or ringwoodite to Mw þ ðMg;FeÞSiO 3 Pv were previously studied using high-pressure generating devices (26)(27)(28)(29)(33)(34)(35). Microtextural evolution from lamellar into equigranular, similar to the textural sequence encountered here, was previously observed with increasing temperature but at the same pressure conditions.…”

Section: Resultssupporting

confidence: 72%

Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite

Miyahara

Ohtani

Ozawa

et al. 2011

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

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We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine ) adjacent to or entrained in the shock melt vein and melt pockets of Martian meteorite olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO 3 perovskite (Pv)þmagnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular O livine is one of the major constituent minerals of terrestrial planets. High-pressure and high-temperature experiments indicate that olivine converts in solid state to its high-pressure polymorphs, ringwoodite subsequent to wadsleyite, with increasing pressure and temperature and finally dissociates at higher pressures to ðMg;FeÞSiO 3 perovskite ðPvÞ þ magnesiowüstite ðMwÞ. It is expected that the dissociation takes place around and below the transition zone of the Earth (1). Seismic observations suggest that ðMg;FeÞSiO 3 Pv and Mw are likely the dominant constituent minerals in the lower mantle. Accordingly, its dissociation mechanism is important to understand the dynamics of the Earth's interior because it affects the physical and chemical properties such as densities and elastic velocities of mantle materials. Since the experimental discovery of the dissociation reaction, many scholars have been searching for evidence for the decomposition reactions in natural samples such as inclusions in diamonds from kimberlites. However, the dissociation of olivine at high-pressure and high-temperature conditions has never been reported from any natural samples so far. Therefore, the dissociation mechanism of olivine in natural samples is still unclear.Planetesimal collision phenomena are recorded in many chondritic, lunar, and Martian meteorites as shock melt veins or melt pockets. Olivine in and around the shock melt veins or melt pockets was converted by the dynamic events in solid-state reactions to its high-pressure polymorphs or its shock-induced monomineralic melt fractionally crystallized to Mg-rich wadsleyite and Fe-rich ringwoodite at high-pressure and high-temperature conditions induced by the dynamic events (2-7). The high-pressure and high-temperature conditions of the dynamic event recorded in Martian meteorites have been estimated by several previous works (8)(9)(10)(11)(12)(13)(14)(15), and the estimated conditions given in some reports are considerably beyond the stability filed of ringwoodite (8, 11). It is likely that olivine dissociated to ðMg;FeÞSiO 3 Pv þ Mw but was overlooked. Accordingly, we carefully scanned olivine grains in the Martian meteorite Dar al Gani (DaG) 735 with a field emission (FE) SEM and laser micro-Raman spectroscopy. Here ...

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Section: Resultssupporting

confidence: 72%

Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite

Miyahara

Ohtani

Ozawa

et al. 2011

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

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“…These ringwoodite lamellae form platelets from several unit cells to 100 nm in thickness (6,(10)(11)(12)(14)(15)(16)(17)(18). The formation of ringwoodite lamellae in olivine was attributed either to a martensitic transformation mechanism (6,13,(15)(16)(17)(18)(19) or an intracrystalline nucleation and growth mechanism by which coherent nucleation of ringwoodite occurs on the stacking faults of olivine (10-12). However, no natural occurrence of ringwoodite lamellae had been found so far either in the shocked meteorites or exhumed subducted slabs.…”

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confidence: 99%

“…An experiment-produced texture characteristic of this phase transition in the slabs is the formation of ringwoodite lamellae within individual olivine crystals (6,7,(10)(11)(12). A number of laboratory experiments on compositions like Mg 2 GeO 4 , Fe 2 SiO 4 , and (Mg,Fe) 2 SiO 4 showed that the spinel-structured lamellae lie parallel to the (100) planes of olivine (6,(10)(11)(12)(13)(14)(15)(16)(17)(18). These ringwoodite lamellae form platelets from several unit cells to 100 nm in thickness (6,(10)(11)(12)(14)(15)(16)(17)(18).…”

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confidence: 99%

“…A number of laboratory experiments on compositions like Mg 2 GeO 4 , Fe 2 SiO 4 , and (Mg,Fe) 2 SiO 4 showed that the spinel-structured lamellae lie parallel to the (100) planes of olivine (6,(10)(11)(12)(13)(14)(15)(16)(17)(18). These ringwoodite lamellae form platelets from several unit cells to 100 nm in thickness (6,(10)(11)(12)(14)(15)(16)(17)(18). The formation of ringwoodite lamellae in olivine was attributed either to a martensitic transformation mechanism (6,13,(15)(16)(17)(18)(19) or an intracrystalline nucleation and growth mechanism by which coherent nucleation of ringwoodite occurs on the stacking faults of olivine (10)(11)(12).…”

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Ringwoodite lamellae in olivine: Clues to olivine–ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs

Chen

Goresy

Gillet

2004

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

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The first natural occurrence of ringwoodite lamellae was found in the olivine grains inside and in areas adjacent to the shock veins of a chondritic meteorite, and these lamellae show distinct growth mechanism. Inside the veins where pressure and temperature were higher than elsewhere, ringwoodite lamellae formed parallel to the {101} planes of olivine, whereas outside they lie parallel to the (100) plane of olivine. The lamellae replaced the host olivine from a few percent to complete. Formation of these lamellae relates to a diffusion-controlled growth of ringwoodite along shear-induced planar defects in olivine. The planar defects and ringwoodite lamellae parallel to the {101} planes of olivine should have been produced in higher shear stress and temperature region than that parallel to the (100) plane of olivine. This study suggests that the time duration of high pressure and temperature for the growth of ringwoodite lamellae might have lasted at least for several seconds, and that an intracrystalline transformation mechanism of ringwoodite in olivine could favorably operate in the subducting lithospheric slabs in the deep Earth. N atural ringwoodite had been found in many shocked chondritic meteorites, in which the ringwoodite occurs as finegrained polycrystalline aggregates formed through a phase transition of olivine during exogenous dynamic events on the parent asteroids (1-4). It was also suggested that the olivineringwoodite transformation could take place in cold subducting slabs at the deep transition zone, where pressure oversteps the ringwoodite stability field (5-9). An experiment-produced texture characteristic of this phase transition in the slabs is the formation of ringwoodite lamellae within individual olivine crystals (6,7,(10)(11)(12). A number of laboratory experiments on compositions like Mg 2 GeO 4 , Fe 2 SiO 4 , and (Mg,Fe) 2 SiO 4 showed that the spinel-structured lamellae lie parallel to the (100) planes of olivine (6,(10)(11)(12)(13)(14)(15)(16)(17)(18). These ringwoodite lamellae form platelets from several unit cells to 100 nm in thickness (6,(10)(11)(12)(14)(15)(16)(17)(18). The formation of ringwoodite lamellae in olivine was attributed either to a martensitic transformation mechanism (6,13,(15)(16)(17)(18)(19) or an intracrystalline nucleation and growth mechanism by which coherent nucleation of ringwoodite occurs on the stacking faults of olivine (10-12). However, no natural occurrence of ringwoodite lamellae had been found so far either in the shocked meteorites or exhumed subducted slabs.Sixiangkou meteorite is a heavily shock-metamorphosed L6-chondrite with a number of shock-produced veins up to 10 mm in thickness. The shock veins contain abundant high-pressure minerals including ringwoodite, majorite, garnet, and magnesiowüstite, for which the shock-produced pressure and temperature of Ϸ20 GPa and 2,000°C were inferred (4). Polycrystalline aggregates of ringwoodite and majorite up to 100 m in size and porphyroclastic grains of olivine and pyroxene up to 1.5 mm in size distr...

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“…The transformation of olivine to ringwoodite can be proceeded by an incoherent intercrystalline diffusioncontrolled mechanism (Sung and Burns 1976;Vaughan et al 1982) or an interface-controlled mechanism (Liu et al 1998;Mosenfelder et al 2001), a coherent intracrystalline martensitic transformation (Poirier 1981;Boland and Liu 1983;Burnley and Green 1989;Madon et al 1989), or a nucleation and growth (Kerschhofer et al 1996) mechanism. So far, natural ringwoodite has been identified only in shockmetamorphosed meteorites, where it mainly occurs as finegrained polycrystalline aggregates (Price et al 1979;Madon and Poirier 1983;Chen et al 1996).…”

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confidence: 99%

Fracture-related intracrystalline transformation of olivine to ringwoodite in the shocked Sixiangkou meteorite

Chen

Goresy

et al. 2006

Meteoritics &Amp; Planetary Science

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Abstract-Magnesium-iron olivine in the Sixiangkou L6 chondrite contains abundant fractures induced by plastic deformation during shock metamorphism. This study reports the discovery of lamellar ringwoodite that incoherently nucleated and grew along planar and irregular fractures in olivine. Magnesium-iron interdiffusion took place between olivine matrix and crystallizing ringwoodite at high pressures and high temperatures, which resulted in higher FeO content in ringwoodite lamellae than in olivine. This suggests that a quasi-hydrostatic high pressure lasting for several minutes should have been produced in the shock veins of the meteorite. The intracrystalline transformation of olivine to ringwoodite also has implications for phase transitions in subducting lithospheric slabs because planar and irregular fractures are commonly produced in olivine that suffered plastic deformation.

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Electron microscopy of high-pressure phases synthesized from natural olivine in diamond anvil cell

Cited by 56 publications

References 40 publications

Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite

Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite

Ringwoodite lamellae in olivine: Clues to olivine–ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs

Fracture-related intracrystalline transformation of olivine to ringwoodite in the shocked Sixiangkou meteorite

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Electron microscopy of high-pressure phases synthesized from natural olivine in diamond anvil cell

Cited by 56 publications

References 40 publications

Natural dissociation of olivine to (Mg,Fe)SiO 3 perovskite and magnesiowüstite in a shocked Martian meteorite

Natural dissociation of olivine to (Mg,Fe)SiO 3 perovskite and magnesiowüstite in a shocked Martian meteorite

Ringwoodite lamellae in olivine: Clues to olivine–ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs

Fracture-related intracrystalline transformation of olivine to ringwoodite in the shocked Sixiangkou meteorite

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Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite

Natural dissociation of olivine to (Mg,Fe)SiO ₃ perovskite and magnesiowüstite in a shocked Martian meteorite