Crystal chemistry of the mixed-layer sequence talc–talc-smectite–smectite from submarine hydrothermal vents
-
Javier Cuadros
,
Vesselin M. Dekov
Abstract
Clay samples of hydrothermal origin from several oceanic spreading centers were studied using XRD, microprobe, infrared, and thermal analysis. They are talc, smectite, and mixed-layer talc-smectite (T-S) where the talc layers have several degrees of crystalline order. The smectite is trioctahedral in most cases, but there is also dioctahedral smectite both as mixed-layer and as a separate phase. All specimens contain Fe3+, some of them in moderate amounts (up to 17% Fe2O3) distributed between the tetrahedral and octahedral sheets (maximum values: IVFe = 0.32, VIFe = 0.68, per O10[OH]2). Octahedral Fe abundance correlates with the presence of molecular water that is lost in a well-defined dehydration event above 200 °C. This water does not cause layer expansion and is interpreted to be present within the pseudo-hexagonal cavity, next to Fe3+ ions that generate a local charge imbalance. The presence of octahedral Fe3+ is accompanied by vacancies in the octahedral sheet to balance the excess positive charge. An infrared band at ~790 cm-1 is assigned to OH bending in the group Fe-Mg-□-OH. Analysis of this band suggests a range of short-range Fe-□ distributions, from random to ordered. Our sequece talc, T-S, trioctahedral smectite is defined by an increasing Al for Si substitution in the tetrahedra and increasing crystal disorder. The presence of Fe also causes crystal defects. This mixed-layer series can be considered as a continuum generated by the combination of chemical and crystal defect variability. Kerolite was used to designate disordered, hydrated talc. We find that there is no clear line delimiting talc from kerolite as a single phase or in mixed-layer minerals and that it is better to use a descriptive term for the latter such as “disordered talc.” Dioctahedral smectite is also a possible end-member of the mixed-layer sequence, which implies an Al + □ for Mg substitution in the octahedral sheet. If T-S consists of polar TOT layers, the existence of dioctahedral smectite in T-S raises the question of the actual composition of the octahedral sheets within polar TOT layers.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Hydrothermal synthesis of hematite spherules and jarosite: Implications for diagenesis and hematite spherule formation in sulfate outcrops at Meridiani Planum, Mars
- Concentric slow cooling of a low-P–high-T terrane: Evidence from 1600–1300 Ma mica dates in the 1780–1700 Ma Black Hills Orogen, South Dakota, U.S.A.
- Monazite ages from carbonatites and high-grade assemblages along the Kambam Fault (Southern Granulite Terrane, South India)
- Forward modeling of the effects of mixed volatile reaction, volume diffusion, and formation of submicroscopic exsolution lamellae on calcite-dolomite thermometry
- A low-temperature phase diagram for ilmenite-rich compositions in the system Fe2O3-FeTiO3
- Dehydrogenation of kaersutitic amphibole under electron beam excitation recorded by changes in Fe3+/ΣFe: An EMP and SIMS study
- Protonation in germanium equivalents of ringwoodite, anhydrous phase B, and superhydrous phase B
- Andreyivanovite: A second new phosphide from the Kaidun meteorite
- The crystal chemistry of whitlockite and merrillite and the dehydrogenation of whitlockite to merrillite
- Single-crystal elastic properties of (Mg0.987,Fe0.013)O to 9 GPa
- Stoichiometry of synthetic ulvöspinel single crystals
- Thermal behavior and structural transformation in the chabazite-type zeolite willhendersonite, KCaAl3Si3O12·5H2O
- The kinetics and mechanisms of schwertmannite transformation to goethite and hematite under alkaline conditions
- Crystal chemistry of the mixed-layer sequence talc–talc-smectite–smectite from submarine hydrothermal vents
- Crystal chemical and structural characterization of fibrous tremolite from Susa Valley, Italy, with comments on potential harmful effects on human health
- Thermodynamic properties of CaTh(PO4)2 synthetic cheralite
- A computational study of order-disorder phenomena in Mg2TiO4 spinel (qandilite)
- Mineralogical characterization of silica sinters from the El Tatio geothermal field, Chile
- Influence of multi-electron excitation on EXAFS spectroscopy of trivalent rare-earth ions and elucidation of change in hydration number through the series
- Pressure-induced over-hydration and water ordering in gismondine: A synchrotron powder diffraction study
- 57Fe Mössbauer study of the oxidation state of iron in stilpnomelane from granite pegmatites in Poland
- Constraints on structural models of ferrihydrite as a nanocrystalline material
- Pb+ irradiation of synthetic zircon (ZrSiO4): Infrared spectroscopic investigation
- Equation of state and crystal structure of a new germanate post-titanite phase
- Synthetic hypersilicic Cl-bearing mica in the phlogopite-celadonite join: A multimethodical characterization of the missing link between di- and tri-octahedral micas at high pressures
- The effect of crystal-melt partitioning on the budgets of Cu, Au, and Ag
- Thermodynamics of dehydration in analcime: Absorption calorimetry and equilibrium observations
- Accommodation of the carbonate ion in fluorapatite synthesized at high pressure
- Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature
- Letter. Identification of randomly interstratified illite/smectite with basal peak widths
Articles in the same Issue
- Hydrothermal synthesis of hematite spherules and jarosite: Implications for diagenesis and hematite spherule formation in sulfate outcrops at Meridiani Planum, Mars
- Concentric slow cooling of a low-P–high-T terrane: Evidence from 1600–1300 Ma mica dates in the 1780–1700 Ma Black Hills Orogen, South Dakota, U.S.A.
- Monazite ages from carbonatites and high-grade assemblages along the Kambam Fault (Southern Granulite Terrane, South India)
- Forward modeling of the effects of mixed volatile reaction, volume diffusion, and formation of submicroscopic exsolution lamellae on calcite-dolomite thermometry
- A low-temperature phase diagram for ilmenite-rich compositions in the system Fe2O3-FeTiO3
- Dehydrogenation of kaersutitic amphibole under electron beam excitation recorded by changes in Fe3+/ΣFe: An EMP and SIMS study
- Protonation in germanium equivalents of ringwoodite, anhydrous phase B, and superhydrous phase B
- Andreyivanovite: A second new phosphide from the Kaidun meteorite
- The crystal chemistry of whitlockite and merrillite and the dehydrogenation of whitlockite to merrillite
- Single-crystal elastic properties of (Mg0.987,Fe0.013)O to 9 GPa
- Stoichiometry of synthetic ulvöspinel single crystals
- Thermal behavior and structural transformation in the chabazite-type zeolite willhendersonite, KCaAl3Si3O12·5H2O
- The kinetics and mechanisms of schwertmannite transformation to goethite and hematite under alkaline conditions
- Crystal chemistry of the mixed-layer sequence talc–talc-smectite–smectite from submarine hydrothermal vents
- Crystal chemical and structural characterization of fibrous tremolite from Susa Valley, Italy, with comments on potential harmful effects on human health
- Thermodynamic properties of CaTh(PO4)2 synthetic cheralite
- A computational study of order-disorder phenomena in Mg2TiO4 spinel (qandilite)
- Mineralogical characterization of silica sinters from the El Tatio geothermal field, Chile
- Influence of multi-electron excitation on EXAFS spectroscopy of trivalent rare-earth ions and elucidation of change in hydration number through the series
- Pressure-induced over-hydration and water ordering in gismondine: A synchrotron powder diffraction study
- 57Fe Mössbauer study of the oxidation state of iron in stilpnomelane from granite pegmatites in Poland
- Constraints on structural models of ferrihydrite as a nanocrystalline material
- Pb+ irradiation of synthetic zircon (ZrSiO4): Infrared spectroscopic investigation
- Equation of state and crystal structure of a new germanate post-titanite phase
- Synthetic hypersilicic Cl-bearing mica in the phlogopite-celadonite join: A multimethodical characterization of the missing link between di- and tri-octahedral micas at high pressures
- The effect of crystal-melt partitioning on the budgets of Cu, Au, and Ag
- Thermodynamics of dehydration in analcime: Absorption calorimetry and equilibrium observations
- Accommodation of the carbonate ion in fluorapatite synthesized at high pressure
- Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature
- Letter. Identification of randomly interstratified illite/smectite with basal peak widths
