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A Kyono - One of the best experts on this subject based on the ideXlab platform.
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synthesis of thallium leucite tlalsi 2 o 6 Pseudomorph after analcime
Mineralogical Magazine, 1999Co-Authors: A Kyono, Mitsuyoshi Kimata, Masahiro Shimizu, S Saito, Norimasa Nishida, T HattaAbstract:Thallium leucite, TlAlSi 2 O 6 , has been synthesized at 450 degrees C for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaAlSi 2 O 6 in the presence of excess T1C1. This substitution of T1 for Na leads to confirmation of a thallium-leucite Pseudomorph after analcime. Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic T1-leucites. The IR spectra show that the mid-IR modes T-O stretching and T-O-T bending vibrations for TlAlSi 2 O 6 are more resemblant of those for analcime than for leucite, KAlSi 2 O 6 . This resemblance implies that T1 cation enters the W-site rather than the S-site in the analcime structure: Na (S)+H 2 O (W) []+K (leucite) +[]Tl (Tl-leucite), where [] represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, Tl (super +) cations being larger than Na (super +) plainly prefer the latter site to the former. One inference from the binding energy for Tl (super +) by XPS is that Tl (super +) occupies the extra-framework site in synthetic leucite Pseudomorph, rather than the smaller tetrahedral site. The difference in A1/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the []Si 3 O 6 component into the leucite structure may provide a fundamental insight into understanding why TlAlSi 2 O 6 deviates from the trend defined by K-, Rb- and CsAlSi 2 O 6 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of TlAlSi 2 O 6 leucite has an implication for the existence of other polymorphs due to different degrees of Al/Si disordering, except for high- and low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes.
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synthesis of thallium leucite tlalsi2o6 Pseudomorph after analcime
Mineralogical Magazine, 1999Co-Authors: A KyonoAbstract:Thallium leucite, T1A1Si206, has been synthesized at 450~ for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaA1Si206 in the presence of excess T1C1. This substitution of TI for Na leads to confirmation of a thallium-leucite Pseudomorph after analcime, Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic Tl-leucites. The IR spectra show that the mid-lR modes T-O stretching and T-O-T bending vibrations for TIA1Si206 are more resemblant of those for analcime than for leucite, KA1Si206. This resemblance implies that TI cation enters the W-site rather than the S-site in the analcime structure: Na (S) + H20 (W) ~[] + K (leucite) ~ [] + T1 (T1leucite), where [] represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, T1 + cations being larger than Na + plainly prefer the latter site to the former. One inference from the binding energy for T1 + by XPS is that T1 + occupies the extra-framework site in synthetic leucite Pseudomorph, rather than the smaller tetrahedral site. The difference in A1/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the []Si306 component into the leucite structure may provide a fundamental insight into understanding why T1A1Si206 deviates from the trend defined by K-, Rband CsA1Si206 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of T1A1Si206 leucite has an implication for the existence of other polymorphs due to different degrees of A1/Si disordering, except for highand low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes.
Jeanpierre Brun - One of the best experts on this subject based on the ideXlab platform.
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preservation of subduction related prograde deformation in lawsonite Pseudomorph bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
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Preservation of subduction‐related prograde deformation in lawsonite Pseudomorph‐bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
Melody Philippon - One of the best experts on this subject based on the ideXlab platform.
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preservation of subduction related prograde deformation in lawsonite Pseudomorph bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
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Preservation of subduction‐related prograde deformation in lawsonite Pseudomorph‐bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
T Hatta - One of the best experts on this subject based on the ideXlab platform.
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synthesis of thallium leucite tlalsi 2 o 6 Pseudomorph after analcime
Mineralogical Magazine, 1999Co-Authors: A Kyono, Mitsuyoshi Kimata, Masahiro Shimizu, S Saito, Norimasa Nishida, T HattaAbstract:Thallium leucite, TlAlSi 2 O 6 , has been synthesized at 450 degrees C for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaAlSi 2 O 6 in the presence of excess T1C1. This substitution of T1 for Na leads to confirmation of a thallium-leucite Pseudomorph after analcime. Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic T1-leucites. The IR spectra show that the mid-IR modes T-O stretching and T-O-T bending vibrations for TlAlSi 2 O 6 are more resemblant of those for analcime than for leucite, KAlSi 2 O 6 . This resemblance implies that T1 cation enters the W-site rather than the S-site in the analcime structure: Na (S)+H 2 O (W) []+K (leucite) +[]Tl (Tl-leucite), where [] represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, Tl (super +) cations being larger than Na (super +) plainly prefer the latter site to the former. One inference from the binding energy for Tl (super +) by XPS is that Tl (super +) occupies the extra-framework site in synthetic leucite Pseudomorph, rather than the smaller tetrahedral site. The difference in A1/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the []Si 3 O 6 component into the leucite structure may provide a fundamental insight into understanding why TlAlSi 2 O 6 deviates from the trend defined by K-, Rb- and CsAlSi 2 O 6 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of TlAlSi 2 O 6 leucite has an implication for the existence of other polymorphs due to different degrees of Al/Si disordering, except for high- and low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes.
Frederic Gueydan - One of the best experts on this subject based on the ideXlab platform.
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preservation of subduction related prograde deformation in lawsonite Pseudomorph bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
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Preservation of subduction‐related prograde deformation in lawsonite Pseudomorph‐bearing rocks
Journal of Metamorphic Geology, 2013Co-Authors: Melody Philippon, Frederic Gueydan, Pavel Pitra, Jeanpierre BrunAbstract:Lawsonite Pseudomorphs are used to identify and distinguish the kinematic records of subduction and exhumation in blueschist-facies rocks from Syros (Cyclades; Greece). Lawsonite is a hydrous mineral that crystallizes at high-pressure and low-temperature conditions. During decompression, lawsonite is typically Pseudomorphed by an aggregate dominated by epidote and paragonite. Such aggregates are easily deformable and if deformation occurs after the lawsonite breakdown, the Pseudomorphs are difficult to distinguish from the matrix. The preservation of the lawsonite crystal shape, despite complete retrogression, indicates therefore that the host blueschist rock has not been affected by penetrative deformation during exhumation, thus providing indication of strain-free conditions. Therefore, tracking the lawsonite growth and destabilization along the P-T path followed by the rocks during a subduction/exhumation cycle provides information about the subduction/exhumation-related deformation. Using microstructural observations and P-T pseudosections calculated with thermocalc, it is inferred that top-to-the-south sense of shear preserved in lawsonite Pseudomorph-bearing blueschists on Syros occurred during the prograde metamorphic path within the lawsonite stability field, and is therefore associated with subduction. On the contrary, the deformation with a top-to-the-north sense of shear is observed in surrounding rocks, where lawsonite Pseudomorphs are deformed or apparently lacking. This deformation occurred after the lawsonite breakdown during exhumation. At the regional scale, exhumation-related deformation is heterogeneous, allowing the preservation of lawsonite Pseudomorphs in significant volumes of blueschists of the central and southern Cyclades. It is argued that such successive shearing deformation events with opposite senses more likely correspond to an exhumation process driven by slab rollback, in which subduction and exhumation are not synchronous.
