High-precision Δ′17O measurements of geothermal H2O and MORB on the VSMOW-SLAP scale: evidence for active oxygen exchange between the lithosphere and hydrosphere
Takashi Sambuichi, U. Tsunogai, Kazushige Kura, F. Nakagawa, T. Ohba
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引用次数: 3
Abstract
have reported 17O-depletion in terrestrial silicates compared with that in hydrospheric H2O such as seawater and meteoric water (Pack et al., 2016; Sharp et al., 2016). The ∆′17O value of mantle-derived silicates ranges from –70 to –30 × 10−6; however, the mean ∆′17O value of meteoric water is +33 × 10−6 and that of seawater collected at various depths is –5 ± 1 × 10−6 (Luz and Barkan, 2010). This difference in ∆′17O between the lithosphere and hydrosphere has been explained by kinetic fractionation of oxygen isotopes during degassing from the magma ocean on the early primitive earth (Tanaka and Nakamura, 2013) or oxygen isotope exchange between the seawater and lithospheric components such as seafloor basalt and continental crust (Pack and Herwartz, 2014; Sengupta et al., 2020; Sengupta and Pack, 2018). The latter explanation has been proposed on the basis of findings that the equilibrium fractionation exponent θ [=ln17α/ln18α; αA-B = RA/ RB where iR corresponds to the abundance ratio of the heavy isotope (iO where i = 17 or 18) to the light isotope (16O).] between silicates and H2O is a funcHigh-precision ∆′17O measurements of geothermal H2O and MORB on the VSMOW-SLAP scale: evidence for active oxygen exchange between the lithosphere and hydrosphere
期刊介绍:
Geochemical Journal is an international journal devoted to original research papers in geochemistry and cosmochemistry. It is the primary journal of the Geochemical Society of Japan. Areas of research are as follows:
Cosmochemistry; Mineral and Rock Chemistry; Volcanology and Hydrothermal Chemistry; Isotope Geochemistry and Geochronology; Atmospheric Chemistry; Hydro- and Marine Chemistry; Organic Geochemistry; Environmental Chemistry.