The oxygen isotope equilibrium fractionation between sulfite species and water

The Takatori hypothermal tin–tungsten vein deposit is composed of wolframite-bearing quartz veins with minor cassiterite, chalcopyrite, pyrite, and lithium-bearing muscovite and sericite. Several wolframite rims show replacement textures, which are assumed to form by iron replacement with manganese postdating the wolframite precipitation. Lithium isotope ratios (δ7Li) of Li-bearing muscovite from the Takatori veins range from −3.1‰ to −2.1‰, and such Li-bearing muscovites are proven to occur at the early stage of mineralization. Fine-grained sericite with lower Li content shows relatively higher δ7Li values, and might have precipitated after the main ore forming event. The maximum oxygen isotope equilibrium temperature of quartz–muscovite pairs is 460 °C, and it is inferred that the fluids might be in equilibrium with ilmenite series granitic rocks. Oxygen isotope ratios (δ18O) of the Takatori ore-forming fluid range from +10‰ to +8‰. The δ18O values of the fluid decreased with decreasing temperature probably because the fluid was mixed with surrounding pore water and meteoric water. The formation pressure for the Takatori deposit is calculated to be 160 MPa on the basis of the difference between the pressure-independent oxygen isotope equilibrium temperature and pressure-dependent homogenization fluid inclusions temperature. The ore-formation depth is calculated to be around 6 km. These lines of evidence suggest that a granitic magma beneath the deposit played a crucial role in the Takatori deposit formation.

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Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

Mineralogical Magazine ◽

10.1180/minmag.2008.072.1.239 ◽

2008 ◽

Vol 72 (1) ◽

pp. 239-242 ◽

Cited By ~ 1

Author(s):

M. Cusack ◽

A. Pérez-Huerta ◽

P. Chung ◽

D. Parkinson ◽

Y. Dauphin ◽

...

Keyword(s):

Oxygen Isotope ◽

Isotope Composition ◽

Seawater Temperature ◽

Environmental Data ◽

Ambient Seawater ◽

Secondary Layer ◽

Vital Effect ◽

Vital Effects ◽

Stable Oxygen ◽

Isotope Equilibrium

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

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Oxygen isotope equilibrium in sulfate–water systems: A revision of geothermometric applications in low-enthalpy systems

Journal of Geochemical Exploration ◽

10.1016/j.gexplo.2012.08.011 ◽

2013 ◽

Vol 124 ◽

pp. 92-100 ◽

Cited By ~ 25

Author(s):

Tiziano Boschetti

Keyword(s):

Oxygen Isotope ◽

Water Systems ◽

Isotope Equilibrium

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Comment on “experimental determination of carbon isotope equilibrium fractionation between dissolved carbonate and carbon dioxide”

Geochimica et Cosmochimica Acta ◽

10.1016/s0016-7037(99)00302-6 ◽

2000 ◽

Vol 64 (3) ◽

pp. 573-574 ◽

Cited By ~ 2

Author(s):

Mahendra P Verma

Keyword(s):

Carbon Dioxide ◽

Experimental Determination ◽

Carbon Isotope ◽

Isotope Equilibrium ◽

Equilibrium Fractionation

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Relationship between δ18O and minor element composition of Terebratalia transversa

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691008075671 ◽

2007 ◽

Vol 98 (3-4) ◽

pp. 443-449 ◽

Cited By ~ 3

Author(s):

Maggie Cusack ◽

David Parkinson ◽

Alberto Pérez-Huerta ◽

Jennifer England ◽

Gordon B. Curry ◽

...

Keyword(s):

Oxygen Isotope ◽

Isotope Composition ◽

Seawater Temperature ◽

Minor Element ◽

Oxygen Isotope Composition ◽

Secondary Layer ◽

Vital Effects ◽

Stable Oxygen ◽

Temperature Proxy ◽

Isotope Equilibrium

ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

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