Armalcolite in crustal paragneiss xenoliths, central Mexico

Hayob, Jodie L.; Essene, Eric J.

doi:10.2138/am-1995-7-817

Cited by 18 publications

(7 citation statements)

References 34 publications

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“…The armalcolite, partly decomposed into ilmenite and rutile, occurs as clusters of subhedral to euhedral crystals in the reaction rims of Opx (Figure 3a). These oxide mineral assemblages were reported in kimberlites [Haggerty, 1975] and paragneiss xenoliths [Hayob and Essene, 1995], and the precipitation of armalcolite and ilmenite is referred to be related to the breakdown of silicates and the reaction of rutile and Fe 2+bearing silicates or melt [Haggerty, 1995]. This is supported by the intergrowth of rutile and ilmenite, rutile mantled with ilmenite, and accompanying surrounding sulfides (Figure 3b).…”

Section: Magnetic Mineralogy Of the Pyroxenite Xenolithssupporting

confidence: 58%

Magnetic mineralogy of pyroxenite xenoliths from Hannuoba basalts, northern North China Craton: Implications for magnetism in the continental lower crust

Zheng

Zeng

et al. 2014

J. Geophys. Res. Solid Earth

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Studies of the petrology, mineral chemistry, and rock magnetic properties of nine pyroxenite xenoliths from Hannuoba basalts, northern North China Craton, have been made to determine the magnetization signature of the continental lower crust. These pyroxenites are weakly magnetic with low average susceptibility (χ) and saturation isothermal remanent magnetization (M rs ) of 39.59 × 10 À8 m 3 kg À1and 12.05 × 10 À3 Am 2 kg À1 , respectively. The magnetic minerals are mainly magnetite, pyrrhotite, and Fe-rich spinel, which significantly contribute to χ and natural remanent magnetization. Magnetite occurs as interstitial microcrystals together with zeolite aggregates, indicating a secondary origin in a supergene environment. In contrast, pyrrhotite and Fe-rich spinel were formed prior to the xenoliths' ascent to the surface, as evidenced by their dominant occurrence as tiny inclusions and thin exsolution lamellae in pyroxene. The Fe-rich spinel has~50% mole fraction of Fe 3 O 4 and corresponds to the strongest magnetization, and its coexistence with Mg-rich spinel implies a reheating event due to the underplating of basaltic magma. Besides, armalcolite and ilmenite were found in the reaction rims between xenoliths and the basalt, but they contribute little to the whole rock magnetization. However, these pyroxenite xenoliths would be nonmagnetic at in situ depths, as well as peridotite and mafic granulite xenoliths derived from the crust-mantle transition zone (~32-42 km). Therefore, we suggest the limiting depth of magnetization at the boundary between weakly magnetic deep-seated (lower crust and upper mantle) xenoliths and strongly magnetic Archean granulite facies rocks (~32 km) in Hannuoba, northern North China Craton.

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Section: Magnetic Mineralogy Of the Pyroxenite Xenolithssupporting

confidence: 58%

Magnetic mineralogy of pyroxenite xenoliths from Hannuoba basalts, northern North China Craton: Implications for magnetism in the continental lower crust

Zheng

Zeng

et al. 2014

J. Geophys. Res. Solid Earth

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“…The ilmenite (FeTiO 3 ) phase is thought to be transformed into armalcolite type ((Mg,Fe 2+ )Ti 2 O 5 ) after a solid state reaction with magnesium silicate (MgSiO 3 ) at very high pressure (~1.4 GPa) that might have occurred by cumulate overturn process [19,20]. The phase equilibria in the MgO-FeO-Fe 2 O 3 -TiO 2 system indicate the stability of armalcolite in the crust at 900–1200 °C [21]. Since ilmenite and armalcolite have been attempted in humidity and remote sensing applications [22,23], their derivative materials could be used as potential materials for sensors applications.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

Tripathy

Pramanik

Manna

et al. 2016

Sensors

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Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E′: 0.225) and glass transition temperature (Tg: −58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials.

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“…Armalcolite is common in lunar rocks, which equilibrated under conditions of low oxygen fugacity, containing iron only in the ferrous state (e.g. Anderson et al 1970;Haggerty 1973;Klemme et al 2006), whereas terrestrial armalcolite is characterized by the presence of Fe 3+ and forms a complex solid solution of the system Fe 2+ Ti 2 O 5 ZFe 3+ 2 TiO 5 ZMgTi 2 O 5 ZTi 3 O 5 (Contini et al 1993;Hayob & Essene 1995). Previous studies have reported the mode of occurrence of armalcolite in terrestrial rocks (lamproites : Velde 1975;Edgar et al 1992;tholeiites: Cawthorn & Biggar 1993;pegmatite: Mets et al 1985;lowercrustal xenoliths: Pedersen 1979lowercrustal xenoliths: Pedersen , 1981mantle xenoliths: Haggerty 1987;Grégoire et al 2000).…”

mentioning

confidence: 99%

Possible armalcolite pseudomorph-bearing garnet–sillimanite gneiss from Skallevikshalsen, Lützow-Holm Complex, East Antarctica: Implications for ultrahigh-temperature metamorphism

Kawasaki

Adachi

Nakano

et al. 2013

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A possible armalcolite pseudomorph has been identified in garnet-sillimanite gneiss from Skallevikshalsen, located c. 30 km NE of Rundvågshetta, in a terrane with the highest metamorphic grade in the Lützow-Holm Complex, East Antarctica. It occurs as an Fe-Mg-Ti compositional domain consisting of ilmenite, rutile and pseudorutile, partially mantled by rutile within ilmenite. The domain yields an average X Mg of 0.171 + 0.036 exceeding by 3 wt% TiO 2 from armalcolite stoichiometry, while the analysis closest to armalcolite stoichiometry has an X Mg value close to 0.202. Host ilmenite with 0.4 mol% hematite is in contact with prismatic sillimanite, quartz, plagioclase and K-feldspar.In run products of annealing experiments performed to investigate the origin of the pseudomorph, armalcolite-ilmenite reaction coronae were developed around relict rutile in rock fragments of quartz eclogite from the Higashi-Akaishi mass of the Sanbagawa belt, central Shikoku, Japan. The experiments were carried out at 1 atm and 960-1050 8C with wüstite-magnetite buffer and imply a minimum temperature of 1290 8C for armalcolite stability when extrapolated to Skallevikshalsen pressures of 1.0 GPa. Mineral chemistry thermobarometry for Skallevikshalsen yields a metamorphic path with P-T peak conditions of 0.88-1.1 GPa and 970-1050 8C, followed by retrograde metamorphism at 0.6 GPa and 780 8C, and finally metasomatic alteration at c. 630 8C. This P -T path matches that for similar ultrahigh-temperature metamorphic rocks from Rundvågshetta and Sri Lanka, and is markedly lower in temperature than the unreasonable estimates based on armalcolite stability. This discrepancy is inferred to reflect chemical impurities in armalcolite that lower its minimum temperature stability by more than 200 8C.

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Armalcolite in crustal paragneiss xenoliths, central Mexico

Cited by 18 publications

References 34 publications

Magnetic mineralogy of pyroxenite xenoliths from Hannuoba basalts, northern North China Craton: Implications for magnetism in the continental lower crust

Magnetic mineralogy of pyroxenite xenoliths from Hannuoba basalts, northern North China Craton: Implications for magnetism in the continental lower crust

Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

Possible armalcolite pseudomorph-bearing garnet–sillimanite gneiss from Skallevikshalsen, Lützow-Holm Complex, East Antarctica: Implications for ultrahigh-temperature metamorphism

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