Channel CO2 in cordierites

Armbruster, Thomas; Bloss, F. Donald

doi:10.1038/286140a0

Cited by 55 publications

(18 citation statements)

References 3 publications

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“…CaO and K 2 O are below the detection limit. The anhydrous sum of oxides in cordierite is less than 100%, presumably suggesting the presence of volatiles in the structural channels (Armbruster and Bloss, ; Santosh et al, ; Prakash, ; Sharma and Prakash, ).…”

Section: Mineral Chemistrymentioning

confidence: 99%

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

et al. 2017

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Sapphirine-bearing granulite from Usilampatti in the Madurai block of southern India preserves a variety of mineral textures and reactions that help in reconstructing a three-stage metamorphic evolution. Corroded biotite, sillimanite and quartz inclusions within garnet represent relics from the prograde history. Peak metamorphic conditions were attained with the development of sapphirine + quartz in textural equilibrium (Stage 1). This was followed by nearly isothermal decompression, leading to the formation of sapphirine + cordierite at Stage 2. Subsequent retrograde hydration (Stage 3) is only locally evident. Using the Perple_X software and the model system NCKFMASH, the peak P-T conditions were estimated from core compositions, and the retrograde evolution was deduced from rim or symplectite compositions of different minerals as computed by isopleths of X Mg garnet, X Ca garnet, X Mg orthopyroxene, X Mg sapphirine and X Mg biotite. The P-T conditions for Stage 1 thus obtained, and supported by thermodynamic modelling using the winTWQ programme, is approximately 9 kbar and 940°C. Stage 2 conditions were constrained as 6.7 kbar and 900°C. Dating of zircon and monazite in the sapphirine-bearing granulite and associated gneisses by the U-Pb method using LA-ICP-MS indicates metamorphic overprint of zircon (lower intercept ages of discordant data arrays) at 546 ± 8 and 547 ± 11 Ma and metamorphic growth of monazite between 542 ± 3 and 551 ± 2 Ma. Upper intercept ages for zircon point to zircon growth at approximately 2514 ± 66 Ma. Although it remains unclear whether the metamorphic age data refer to Stage 1 or Stage 2 or, most likely, a continuum between both, they clearly document a late Ediacaran age for ultra-high temperature (UHT) metamorphism in the area, which, based on the obtained P-T path, was most likely the result of crustal thickening followed by uplift and erosion. Thus, it is concluded that the sapphirine-bearing granulites formed in response to Pan-African orogeny that led to the collision of the western and eastern Madurai domains, whereas initial zircon growth probably took place during late Neoarchaean arc magmatism that formed much of the western domain.

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Section: Mineral Chemistrymentioning

confidence: 99%

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

et al. 2017

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“…Cordierite rims garnet and is in turn rimmed by biotite. Utilizing the universal stage, the 2 V x angle for two cordierite grains (adjacent to poikilitic orthopyroxene) are high at 96–104°, indicating that these cordierite grains are enriched in CO 2 (Armbruster & Bloss, 1980, 1982; Armbruster et al. , 1982).…”

Section: Mineralogy Mineral Chemistry and Reaction Texturesmentioning

confidence: 99%

Epitaxial quartz inclusions in corundum from a sapphirine–garnet boudin, Bamble Sector, SE Norway: SiO₂–Al₂O₃ miscibility at high P–T dry granulite facies conditions

Kihle¹,

Harlov²,

Frigaard

et al. 2010

Journal Metamorphic Geology

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An Al-rich, SiO 2 -deficient sapphirine-garnet-bearing rock occurs as a metapelitic boudin within granulite facies Proterozoic charnockitic gneisses and migmatites on the island of Hisøy, Bamble Sector, SE Norway. The boudin is made up of peraluminous sapphirine, garnet, corundum, spinel, orthopyroxene, sillimanite, cordierite, staurolite and biotite in a variety of assemblages. Thermobarometric calculations based on coexisting sapphirine-spinel, garnet-corundum-spinel-sillimanite, sapphirine-orthopyroxene, and garnet-orthopyroxene indicate peak-metamorphic conditions near to 930°C at 10 kbar. Corundum occurs as single 200 to 3000 micron sized skeletal crystal intergrowths in cores of optically continuous pristine garnet porphyroblasts. Quartz occurs as 5-60 micron-sized euhedral to lobate inclusions in the corundum where it is in direct contact with the corundum with no evidence of a reaction texture. Some crystal inclusions exhibit growth zoning, which indicates that textural equilibrium was achieved. Electron Back-Scatter Diffraction (EBSD) studies reveal that the quartz inclusions share a common c-axis with the host corundum crystal. The origin of the quartz inclusions in corundum is enigmatic as recent experimental studies have confirmed the instability of quartz-corundum over geologically realistic P-T ranges. The combined EBSD and textural observations suggest the presence of a former silica-bearing proto-corundum, which underwent exsolution during post-peak-metamorphic uplift and cooling. Exsolution of quartz in corundum is probably confined to fluid-absent conditions where phase transitions by coupled dissolution-precipitation mechanisms are prevented.

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“…Molecules occupying Type II sites interact with the large channel cations, while Type I occupants do not. The Type I site can also be filled with various other small molecules, the most common of which is CO 2 (Goldman et al 1977;Armbruster and Bloss 1980;Armbruster 1985;Kolesov and Geiger 2000). Since we will be focusing only on ordered cordierite phases at low temperature here, we simplify the terminology in this paper and designate the M, T 1 1, T 2 6, T 1 6, T 2 1, T 2 3, and Type I H 2 O sites as the Mg1, Al1, Al2, Si1, Si2, Si3, and Ch1 sites, respectively (Type II H 2 O and Na channel sites are not included in our structure refinements).…”

Section: Introductionmentioning

confidence: 99%

High-pressure phases of cordierite from single-crystal X-ray diffraction to 15 GPa

Finkelstein¹,

Dera²,

Duffy³

2015

American Mineralogist

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High-pressure single-crystal X-ray diffraction experiments were conducted on natural cordierite crystals with composition Mg 1.907(18) Fe 0.127(6) Al 4.01(2) Si 4.96(3) Na 0.026(3) O 18.12(9) using a synchrotron X-ray source. The samples were compressed at 300 K in a diamond-anvil cell to a maximum pressure of 15.22(15) GPa with a neon pressure-transmitting medium and a gold pressure calibrant. We observed a recently described orthorhombic to phase transition, as well as a further transition to a second triclinic phase. We solved and refined both new triclinic phases in space group P1, and designate them cordierite II and III. The structures of cordierite II and III were refined at 7.52 (3) and 15.22(15) GPa, respectively. The lattice parameters at these pressures are a = 15.567(3), b = 9.6235(4), c = 9.0658(6) Å, a = 89.963(5)°, b = 86.252(10)°, and g = 90.974(8)° for cordierite II, and a = 8.5191(19), b = 8.2448(3), c = 9.1627(4) Å, a = 85.672(4)°, b = 85.986(7)°, and g = 70.839(10)° for cordierite III.Across the phase transitions there is a significant reduction in the length of the a-axis (~2 Å per phase transition), whereas both the b-and c-axis remain largely unchanged. Cordierite II has fourfold-and fivefold-coordinated Si and Al, while cordierite III has fourfold-, fivefold-, and sixfold-coordinated Si, fourfold-and fivefold-coordinated Al, and fivefold-and sixfold-coordinated Mg. The sequence of high-pressure phases shows increasing polymerization of coordination polyhedra. These results, together with other recent studies, suggest that mixed four-, five-, and sixfold coordination states may occur more commonly in silicate structures compressed at 300 K than previously recognized.

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Channel CO2 in cordierites

Cited by 55 publications

References 3 publications

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

Epitaxial quartz inclusions in corundum from a sapphirine–garnet boudin, Bamble Sector, SE Norway: SiO₂–Al₂O₃ miscibility at high P–T dry granulite facies conditions

High-pressure phases of cordierite from single-crystal X-ray diffraction to 15 GPa

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Channel CO2 in cordierites

Cited by 55 publications

References 3 publications

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

Epitaxial quartz inclusions in corundum from a sapphirine–garnet boudin, Bamble Sector, SE Norway: SiO2–Al2O3 miscibility at high P–T dry granulite facies conditions

High-pressure phases of cordierite from single-crystal X-ray diffraction to 15 GPa

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Epitaxial quartz inclusions in corundum from a sapphirine–garnet boudin, Bamble Sector, SE Norway: SiO₂–Al₂O₃ miscibility at high P–T dry granulite facies conditions