Equilibria among titanite, hedenbergite, fayalite, quartz, ilmenite, and magnetite; experiments and internally consistent thermodynamic data for titanite

Xirouchakis, Dimitrios; Lindsley, D. H.

doi:10.2138/am-1998-7-804

Cited by 73 publications

(30 citation statements)

References 32 publications

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“…Finding natural titanite with a homogeneous bulkcomposition is very difficult. Complex schemes of solid solution, with variations of Ca, Ti, Fe, Al, and F at the percentage level, are common in titanite (Spear 1981, Bernau & Franz 1987, Xirouchakis & Lindsley 1998, Markl & Piazolo 1999, Frost et al 2001, Hayden et al 2008. The chemical composition of titanite can be affected by growth kinetics, and many titanite crystals exhibit complex or sector zoning (Paterson & Stephens 1992).…”

Section: Background Informationmentioning

confidence: 99%

GRENVILLE SKARN TITANITE: POTENTIAL REFERENCE MATERIAL FOR SIMS U-Th-Pb ANALYSIS

Kennedy¹,

Kamo²,

Nasdala³

et al. 2010

The Canadian Mineralogist

132

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We have investigated the homogeneity, chemical composition, structure, degree of radiation damage, and post-formation evolution of titanite crystals from skarns of the Grenville Province of the Canadian Shield using SHRIMP, TIMS, Raman and PL spectroscopy, EBSD, and EPMA-WDS. These results are used to assess the potential of the titanite as Reference Material (RM) for micro-analytical U-Th-Pb age dating. The SHRIMP data show that these megacrysts (5-31g) have concordant U-Pb isotope systematics, 60 to 500 ppm U, 120 to 1200 ppm Th , 206 Pb/ 204 Pb between 500 and 2500, ages of ~1 Ga, and excellent homogeneity at the scale of the analytical volume of the ion probe. The ID-TIMS titanite data for OLT1, OLT2 and TCB show that these crystals are essentially concordant. Data for OLT1 and OLT2 show slight scatter (i.e., in excess of that expected from the uncertainty in an individual analysis). For OLT1, one of seven analyses shows Pb loss or, possibly, a younger period of growth. Crystals OLT1 and OLT2 have respective TIMS concordia ages of 1014.8 ± 2.0 Ma (2s, n = 6, MSWD = 1.8) and 998.0 ± 4.5 Ma (2s, n = 3, MSWD = 3.3) for domains that have not lost Pb. The TIMS analyses of TCB are tightly clustered and give a concordia age of 1018.1 ± 1.7 Ma (2s, n = 4, MSWD = 0.92). Raman and PL spectra show a low to moderate degree of accumulated radiation-induced damage in the Grenville Skarn Titanite crystals and uniform internal distributions of this damage. The EDSB contrast images indicate little or no crystallographic misorientation. The EMPA-WDS data show that the outer 50-100 mm of the OLT1 and TCB crystals are enriched in Al and F, and depleted in Fe and Nb, when compared with the interior. In spite of the variation in composition and degree of radiation damage amongst samples, there are no identifiable matrix effects in our SHRIMP data. Some Grenville skarn titanite (GST) crystals have potential as RM for micro-analytical U-Th-Pb age dating. Crystal TCB has excellent homogeneity of U-Th-Pb isotopic composition. Crystals OLT1 and OLT2 have minor TIMS age heterogeneity. However, this heterogeneity is smaller than that of the Khan titanite, our current in-house titanite standard. Careful selection of analysis areas during SIMS, and of chips for TIMS analysis, allows high-quality isotopic data to be obtained from these large crystals of titanite.

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Section: Background Informationmentioning

confidence: 99%

GRENVILLE SKARN TITANITE: POTENTIAL REFERENCE MATERIAL FOR SIMS U-Th-Pb ANALYSIS

Kennedy¹,

Kamo²,

Nasdala³

et al. 2010

The Canadian Mineralogist

132

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“…The Woshui syenites contain titanite-quartz-magnetite assemblage which suggests fO 2 conditions at or more oxidizing than the FMQ buffer (Wones, 1989;Xirouchakis and Lindsley, 1998). The ilmenite-magnetite pairs indicate sub-solidus temperatures (390°C to 590°C) and the calculated average oxidation state relative to the FMQ buffer (DFMQ) is 1.66, indicating that at least the final stages of the magma were likely oxidized (Fig.…”

Section: Magmatic Oxidation Statesmentioning

confidence: 99%

Oxidation zonation within the Emeishan large igneous province: Evidence from mantle-derived syenitic plutons

Shellnutt

Iizuka

2012

Journal of Asian Earth Sciences

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“…He calculated the equilibrium temperature and oxygen fugacity for reactions with the participation of titanite with pure phases in the CaO -FeO -Fe 2 O 3 -TiO 2 -SiO 2 system at atmospheric pressure. Subsequently, these reactions were studied in experiment (Xirouchakis and Lindsley, 1998). The experimental data were used for specifying thermodynamic characteristics of titanite, which made it possible to calculate the complete diagrams (Xirouchakis et al, 2001a).…”

Section: Ryabchikov Kogarkomentioning

confidence: 99%

“…Titanites also may contain 0.5-1.0 wt % Nb 2 O 5 + Ta 2 O 5 , about 0.5 wt % REE, 0.2-0.4 wt % ZrO 2 , and probably are water-bearing (Fig. 10).THERMODYNAMIC CALCULATIONSTo estimate in rocks of the apatite-bearing intrusion, we used experimental and calculated data for the magnetite + ilmenite + titanite + hedenbergite + SiO 2 phase assemblage(Xirouchakis and Lindsley, 1998;Xirouchakis et al, 2001aXirouchakis et al, , 2001b, which correspond to the reaction Relationships between titanite (Tnt), clinopyroxene (Cpx), and magnetite (Mt) in rocks of the Khibiny pluton, Sample Khib-50. Ne, nepheline; Ap, apatite.…”

mentioning

confidence: 99%

Redox potential of the Khibiny magmatic system and genesis of abiogenic hydrocarbons in alkaline plutons

Ryabchikov

Kogarko

2009

Geol. Ore Deposits

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The temperature and redox conditions of the crystallization of rocks from the Khibiny alkaline pluton have been estimated based on an analysis of coexisting magnetite, ilmenite, titanite, and pyroxene. Under redox conditions characteristic of the Khibiny Complex, CO 2 is contained in fluid and carbonate anions are contained in melt at high temperature; then graphite is released and an appreciable amount of hydrocarbons appear at a lower temperature as products of reaction of graphite with fluid. Abiogenic hydrocarbons can arise in igneous complexes owing to a processes distinct from Fischer-Tropsch synthesis.

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Equilibria among titanite, hedenbergite, fayalite, quartz, ilmenite, and magnetite; experiments and internally consistent thermodynamic data for titanite

Cited by 73 publications

References 32 publications

GRENVILLE SKARN TITANITE: POTENTIAL REFERENCE MATERIAL FOR SIMS U-Th-Pb ANALYSIS

GRENVILLE SKARN TITANITE: POTENTIAL REFERENCE MATERIAL FOR SIMS U-Th-Pb ANALYSIS

Oxidation zonation within the Emeishan large igneous province: Evidence from mantle-derived syenitic plutons

Redox potential of the Khibiny magmatic system and genesis of abiogenic hydrocarbons in alkaline plutons

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