Compositional zoning and element partitioning in nickeloan tourmaline from a metamorphosed karstbauxite from Samos, Greece
-
Darrell J. Henry
and
Barbara L. Dutrow
Abstract
Blue-green nickeloan tourmaline from a micaceous enclave of a marble from Samos, Greece, contains unusually high concentrations of Ni (up to 3.5 wt% NiO), Co (up to 1.3 wt% CoO), and Zn (up to 0.8 wt% ZnO). The polymetamorphic karstbauxite sample has an uncommon assemblage of nickeloan tourmaline, calcite, zincian staurolite, gahnite, zincohögbomite, diaspore, muscovite, paragonite, and rutile. The complex geologic history is reflected in multi-staged tourmaline growth, with cores that represent detrital fragments surrounded by two-staged metamorphic overgrowths. Zone-1 metamorphic overgrowths, which nucleated next to detrital cores, are highly asymmetric and exhibit compositional polarity such that narrow overgrowths of brown schorl developed at the (-) c-pole are enriched in Mg, Ti, and F, and depleted in Al, Fe, and X-site vacancies (x⃞ ) relative to wider, gray-blue schorl-to-foitite overgrowths developed at the (+) c-pole. Volumetrically dominant Zone-2 overgrowths are strongly zoned nickeloan dravites with a continuous increase in Mg, Co, Ca, and F at the expense of Fe, Zn, Cr, and V from the Zone-1 interface to the outermost rim. Within Zone 2, Ni reaches a maximum of 0.5 apfu before decreasing in the outer 20-40 µm. Zone-2 overgrowths also exhibit compositional polarity such that, at the (-) c-pole, overgrowths are enriched in Mg, F, Na, Ca, and Cr relative to overgrowths at the (+) c-pole that are, in turn, enriched in Al, Fe, Ni, Co, and X⃞ . Element partitioning involving tourmaline rims and coexisting minerals indicates that relative partitioning of Ni is tourmaline >> staurolite > gahnite; Co is tourmaline > staurolite > gahnite; and Zn is gahnite > staurolite >> tourmaline.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer
- Compositional zoning and element partitioning in nickeloan tourmaline from a metamorphosed karstbauxite from Samos, Greece
- Occurrence of apatite associated with magnetite in an ophiolite complex (Othrys), Greece
- Overpressures induced by coesite-quartz transition in zircon
- Geochemical modeling of bacterially induced mineralization of schwertmannite and jarosite in sulfuric acid spring water
- H2O-D2O exchange in lawsonite
- Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: a time-of-flight neutron powder diffraction and EXAFS study
- Thermal conductivity of spinels and olivines from vibrational spectroscopy: Ambient conditions
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- The crystal chemistry of birefringent natural uvarovites: Part II. Single-crystal X-ray structures
- Ferroanthophyllite in Rockport grunerite: A transmission electron microscopy study
- Crystal structure of a new (21)-clinopyribole synthesized at high temperature and pressure
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- Raman spectroscopic studies of phase E to 19 GPa
- The crystal structures of the low-temperature phases of leonite-type compounds, K2Me(SO4)2·4H2O (Me2+ = Mg, Mn, Fe)
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- Pristine surface growth features on 100 Ma garnet phenocrysts: Interference imaging results
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Articles in the same Issue
- Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer
- Compositional zoning and element partitioning in nickeloan tourmaline from a metamorphosed karstbauxite from Samos, Greece
- Occurrence of apatite associated with magnetite in an ophiolite complex (Othrys), Greece
- Overpressures induced by coesite-quartz transition in zircon
- Geochemical modeling of bacterially induced mineralization of schwertmannite and jarosite in sulfuric acid spring water
- H2O-D2O exchange in lawsonite
- Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: a time-of-flight neutron powder diffraction and EXAFS study
- Thermal conductivity of spinels and olivines from vibrational spectroscopy: Ambient conditions
- Elasticity of six polycrystalline silicate garnets at pressure up to 3.0 GPa
- The crystal chemistry of birefringent natural uvarovites: Part I. Optical investigations and UV-VIS-IR absorption spectroscopy
- The crystal chemistry of birefringent natural uvarovites: Part II. Single-crystal X-ray structures
- Ferroanthophyllite in Rockport grunerite: A transmission electron microscopy study
- Crystal structure of a new (21)-clinopyribole synthesized at high temperature and pressure
- The Mg(Fe)SiO3 orthoenstatite-clinoenstatite transitions at high pressures and temperatures determined by Raman-spectroscopy on quenched samples
- Raman spectroscopic studies of phase E to 19 GPa
- The crystal structures of the low-temperature phases of leonite-type compounds, K2Me(SO4)2·4H2O (Me2+ = Mg, Mn, Fe)
- Carraraite and zaccagnaite, two new minerals from the Carrara marble quarries: their chemical compositions, physical properties, and structural features
- Pristine surface growth features on 100 Ma garnet phenocrysts: Interference imaging results
- Oxygen triclusters in crystalline CaAl4O7 (grossite) and in calcium aluminosilicate glasses: 17O NMR
- Low-temperature heat capacity of pentlandite
- Calcium segregation at antiphase boundaries in pigeonite
