Clintonite-bearing assemblages in chondrodite marbles from the contact aureole of the Třebíčský Pluton, Moldanubian Zone, Bohemian Massif

Houzar, Stanislav; Novák, Milan

doi:10.3190/jcgs.997

Cited by 5 publications

(3 citation statements)

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“…Metamorphic evolution of the host rock sequence has not been studied so far. Dolomite marble, the only rock examined in detail in this area, shows the mineral assemblage dolomite + calcite + phlogopite + forsterite + spinel, whereby the formation of the assemblage forsterite + spinel was probably related to the HT/LP metamorphism at c. 540-750 °C for pressures of ~ 2-4 kbar (Novák and Houzar 1996;Houzar and Novák 2006).…”

Section: Geological Settingmentioning

confidence: 99%

Mn3+-rich andalusite to kanonaite and their breakdown products from metamanganolite at Kojetice near Třebíč, the Moldanubian Zone, Czech Republic

Novák¹,

Škoda²

2012

Jour. Geosci.

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A zoned Mn 3+-rich andalusite to kanonaite occurs as shortly prismatic, black-green crystals, up to 2 mm in size, randomly distributed in quartz matrix of quartzitic rock with metamanganolite portions from Kojetice near Třebíč. Minor spessartine, braunite, K-feldspar, albite, hyalophane, rare paragonite and accessory magnetite-rutile intergrowths, tephroite, chernovite-(Y), monazite-(Ce), pyrophanite, Sb-rich rutile, cobaltite, pseudobrookite(?) and pale pink flakes of late muscovite were identified in this rock. Zoned subhedral grains of Mn 3+-rich andalusite to kanonaite have strong pleochroism: X = yellow, Y = green, Z = deep green, when narrow Mn 3+-enriched rims feature slightly more intensive colors. Electron microprobe study shows that the core has always lower contents of Mn 2 O 3 relative to commonly narrow rim of kanonaite. Chemical composition varies from Mn 3+-rich andalusite with 0.21 apfu Mn 3+ (9.72 wt. % Mn 2 O 3) to kanonaite with up to 0.60 apfu Mn 3+ (26.09 wt. % Mn 2 O 3). Minor amount of Fe 2 O 3 from 0.07 to 0.14 apfu Fe 3+ apfu (6.12 wt. % Fe 2 O 3) is typical. In thin sections, subhedral grains of Mn 3+-rich andalusite to kanonaite are enclosed in massive quartz and locally overgrown or replaced by spessartine plus albite/paragonite and later replaced by muscovite. No difference in degree of muscovitization was observed between Mn 3+-rich andalusite and kanonaite. In particular, the abundance of feldspars as well as the total absence of Al 2 SiO 5 minerals and the presence of some rare accessory minerals in Kojetice are different from the other localities of Mn 3+-rich andalusite and kanonaite. The presence of K-feldspar may suggest higher temperature relative to the other mostly low-to medium-grade kanonaite-bearing metamorphic rocks. The following mineral reactions are indicated from textural relations: 3 Mn 3+-rich andalusite (kanonaite) + Na + + 3 quartz = spessartine + albite/paragonite, and 3 Mn 3+-rich andalusite (kanonaite) + K + + H 2 O = muscovite + 3 Mn. The newly formed spessartine requires a decrease in fO 2 , which is also indicated by the presence of accessory tephroite. This is in contrast to the other localities of Mn 3+-rich andalusite to kanonaite described to date, where increasing fO 2 during replacement of these minerals is typical.

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Section: Geological Settingmentioning

confidence: 99%

Mn3+-rich andalusite to kanonaite and their breakdown products from metamanganolite at Kojetice near Třebíč, the Moldanubian Zone, Czech Republic

Novák¹,

Škoda²

2012

Jour. Geosci.

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“…1) represents one of these ultrapotassic bodies. It is composed of amphibole-biotite (quartz) melasyenites to melagranites (durbachites), which were emplaced into medium-to high-grade metamorphic rocks of the Gföhl Unit at upper-crustal levels (~2-4 kbar) (Novák and Houzar 1996;Houzar and Novák 2006;Leichmann et al 2017) at 341.6 ± 2.8 Ma (U-Pb SHRIMP on zircon: Kusiak et al 2010) or 334.8 ± 3.2 Ma (conventional U-Pb on zircon: Kotková et al 2010). The bulk-rock compositions in the Třebíč Pluton are metaluminous (A/CNK = 0.85-0.93) with high concentrations of K 2 O (5.2-6.5 wt.…”

Section: Introductionmentioning

confidence: 99%

Textural and compositional evidence for a polyphase saturation of tourmaline in granitic rocks from the Třebíč Pluton (Bohemian Massif)

Buriánek¹,

Dolníček²,

Novák³

2016

J. Geosci.

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Crystallization of granite melts produced several textural types of granites and pegmatites in the Třebíč Pluton: dykes of volumetrically dominant muscovite-biotite granite (MBG) locally containing tourmaline nodules with leucocratic halos, minor oval pods to dykes of tourmaline granite and veins of tourmaline pegmatite, both enclosed in the MBG. An aplitic zone with comb textures, locally developed in MBG along the contact with surrounding durbachites, suggests high degree of undercooling. Evidence for polyphase saturation of tourmaline was observed within MBG and related granitic rocks including the following textural and compositional types of tourmaline: (i) nodules surrounded by leucocratic halos; (ii) euhedral to subhedral grains randomly distributed within tourmaline granite and tourmaline-quartz accumulations with leucocratic halos in the marginal part of granite dykes; (iii) rare columnar crystals of black tourmaline occurring locally in central parts of pegmatite; (iv) dravite-rich rims and late dravite veinlets in tourmaline grains from nodules, suggesting crystallization from hydrothermal fluids in the system open to host rocks as supported also by fluid inclusions study.

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“…Clintonite (often called xanthophyllite, Forman et al 1967, Guggenheim 1984) is a rare trioctahedral brittle mica with ideal composition Ca(Mg 2 Al)(Al 3 Si)O 10 (OH) 2 , which forms as a result of thermal metamorphism of Ca-and Al-rich, and Si-poor rocks. It was found in chlorite schists, in metasomatically altered limestones, or in siliceous skarns in proximity to the near-contact metamorphic zones (e.g., Warnet and Luth 1973;Raymond 1976;Rice 1979;Tracy 1979;Ulmer 1982;Sugaki et al 2000;Woodford et al 2001;Houzar and Novák 2006). A series of studies have been devoted to the crystal chemistry, phase stability of clintonite, and petrological implications (e.g., Kushiro and Yoder 1964;Olesch 1975;Olesch and Seifert 1976;Annersten and Olesch 1978;Ulmer 1982).…”

Section: Introductionmentioning

confidence: 99%

The thermoelastic behavior of clintonite up to 10 GPa and 1,000°C

Gatta

Merlini

Liermann³

et al. 2012

Phys Chem Minerals

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The thermoelastic behavior of a natural clintonite-1M [with composition: Ca 1.01 (Mg 2.29 Al 0.59 Fe 0.12) R3.00 (Si 1.20 Al 2.80) R4.00 O 10 (OH) 2 ] has been investigated up to 10 GPa (at room temperature) and up to 960°C (at room pressure) by means of in situ synchrotron single-crystal and powder diffraction, respectively. No evidence of phase transition has been observed within the pressure and temperature range investigated. P-V data fitted with an isothermal third-order Birch-Murnaghan equation of state (BM-EoS) give V 0 = 457.1(2) Å 3 , K T0 = 76(3)GPa, and K 0 = 10.6(15). The evolution of the ''Eulerian finite strain'' versus ''normalized stress'' shows a linear positive trend. The linear regression yields Fe(0) = 76(3) GPa as intercept value, and the slope of the regression line leads to a K 0 value of 10.6(8). The evolution of the lattice parameters with pressure is significantly anisotropic [b(a) = 1/3K T0 (a) = 0.0023(1) GPa-1 ; b(b) = 1/3K T0 (b) = 0.0018(1) GPa-1 ; b(c) = 1/K T0 (c) = 0.0072(3) GPa-1 ]. The bangle increases in response to the applied P, with: b P = b 0 ? 0.033(4) P (P in GPa). The structure refinements of clintonite up to 10.1 GPa show that, under hydrostatic pressure, the structure rearranges by compressing mainly isotropically the interlayer Ca-polyhedron. The bulk modulus of the Ca-polyhedron, described using a second-order BM-EoS, is K T0 (Ca-polyhedron) = 41(2) GPa. The compression of the bond distances between calcium and the basal oxygens of the tetrahedral sheet leads, in turn, to an increase in the ditrigonal distortion of the tetrahedral ring, with qa/qP & 0.1°/GPa within the P-range investigated. The Mg-rich octahedra appear to compress in response to the applied pressure, whereas the tetrahedron appears to behave as a rigid unit. The evolution of axial and volume thermal expansion coefficient a with temperature was described by the polynomial a(T) = a 0 ? a 1 T-1/2. The refined parameters for clintonite are as follows: a 0 = 2.78(4) 10-5°C-1 and a 1 =-4.4(6) 10-5°C1/2 for the unit-cell volume; a 0 (a) = 1.01(2) 10-5°C-1 and a 1 (a) =-1.8(3) 10-5°C1/2 for the a-axis; a 0 (b) = 1.07(1) 10-5°C-1 and a 1 (b) =-2.3(2) 10-5°C1/2 for the b-axis; and a 0 (c) = 0.64(2) 10-5°C-1 and a 1 (c) =-7.3(30) 10-6°C1/2 for the c-axis. The bangle appears to be almost constant within the given T-range. No structure collapsing in response to the T-induced dehydroxylation was found up to 960°C. The HP-and HT-data of this study show that in clintonite, the most and the less expandable directions do not correspond to the most and the less compressible directions, respectively. A comparison between the thermoelastic parameters of clintonite and those of true micas was carried out. Keywords Clintonite Á Micas Á High temperature Á High pressure Á Synchrotron diffraction Á Thermal expansion Á Compressibility Electronic supplementary material The online version of this article (

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Clintonite-bearing assemblages in chondrodite marbles from the contact aureole of the Třebíčský Pluton, Moldanubian Zone, Bohemian Massif

Cited by 5 publications

References 14 publications

Mn3+-rich andalusite to kanonaite and their breakdown products from metamanganolite at Kojetice near Třebíč, the Moldanubian Zone, Czech Republic

Mn3+-rich andalusite to kanonaite and their breakdown products from metamanganolite at Kojetice near Třebíč, the Moldanubian Zone, Czech Republic

Textural and compositional evidence for a polyphase saturation of tourmaline in granitic rocks from the Třebíč Pluton (Bohemian Massif)

The thermoelastic behavior of clintonite up to 10 GPa and 1,000°C

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