Stable isotope fractionation between liquid and vapour in water–salt systems up to 600°C

Shmulovich, K. I.; Landwehr, Dirk; Simon, Klaus; Heinrich, Wilhelm

doi:10.1016/s0009-2541(98)00202-2

Cited by 131 publications

(80 citation statements)

References 24 publications

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“…Although phase separation is occurring at Pual Ridge (as discussed previously) and experimental studies have shown that both subcritical and supercritical phase separation processes occurring in seafloor hydrothermal systems can affect the hydrogen and oxygen isotopic composition of vent waters (Horita et al, 1995;Shmulovich et al, 1999;Foustoukos and Seyfried, 2007b) while the reverse is true for oxygen isotope partitioning Foustoukos and Seyfried, 2007b). Examination of the PACMANUS fluids reveals no systematic variations in δD H2O or δ 18 O H2O with endmember Cl (Table 5.2).…”

Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 75%

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH 4 ) formation under hydrothermal conditions. The overall reduction of carbon dioxide (CO 2 ) to CH 4 , previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH 3 SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt-and sediment-hosted hydrothermal systems. Previous assumptions that CH 3 SH forms by reduction of CO 2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backarc hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production. CHAPTER 1 IntroductionSeafloor hydrothermal systems associated with the generation of oceanic crust represent a dramatic expression of heat and mass transfer from the interior of the Earth. In addition to profound effects on ocean chemistry, convective circulation of seawater through volcanically active oceanic crust leads to the formation of metal sulfide deposits. In addition, seafloor hot springs are often invoked as ideal settings from which early microbial life could have emerged.Since the initial discovery of low temperature venting at the Galápagos Spreading Center in 1977 (CORLISS et al., 1979), our understanding of the composition and diversity of hydrothermal solutions has expanded greatly. During convection through oceanic crust of basaltic composition, O 2 -replete seawater reacts with crustal rock, typically producin...

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Section: Isotopic Evidence For Magmatic H 2 Omentioning

confidence: 75%

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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“…Berndt et al 1996;Driesner and Seward 2000;Horita et al 1995;Shmulovich et al 1999) have demonstrated that the approach of using mineral-pure water fractionation factors to deduce the origin of the water is incorrect. Isotope fractionations involving aqueous solutions depend not only on temperature and fluid composition, but also on the presence or absence of phase separation ("boiling").…”

Section: Ore Deposits and Hydrothermal Systemsmentioning

confidence: 99%

“…Phase separation is an important process causing potentially isotope fractionation. Hydrogen isotope studies (Berndt et al 1996;Shmulovich et al 1999) indicate that high temperature phase separation produces D-enrichment in the vapor and D-depletion in the conjugate fluid. If the fractionation effect inherent in a boiling fluid system is disregarded, one may easily misinterpret the isotope composition of hydrothermal minerals, since boiling may mask the source of the parent fluids.…”

Section: Ore Deposits and Hydrothermal Systemsmentioning

confidence: 99%

Variations of Stable Isotope Ratios in Nature

Hoefs¹

2015

Stable Isotope Geochemistry

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“…In contrast, zircon O isotopic composition of the two-mica granites is characterized by a bimodal distribution pattern, pointing to mixing between two isotopic end members. Experimental studies of isotope fractionation indicate that the vapor phase escaping from the saline fluid (25% NaCl) could result in oxygen isotope fractionation of up to 2‰ between liquid and vapour in water-salt systems, with the resultant fluid having relatively enriched 18 O value [59]. Consequently, it seems that the bimodal characteristic of zircon O isotope compositions can be used to trace the features of two isotopic end-members (protolith and altering fluid).…”

Section: Tetrad Effect In Ree Pattern and Highly Evolved Granitesmentioning

confidence: 99%

Petrogenesis of early Yanshanian highly evolved granites in the Longyuanba area, southern Jiangxi Province: Evidence from zircon U-Pb dating, Hf-O isotope and whole-rock geochemistry

Tao

et al. 2013

Sci. China Earth Sci.

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Early Yanshanian (Jurassic) granitoids are widespread in the Nanling Range, South China. Whereas large granitic batholiths commonly crop out in the center of the Nanling Range (corresponding geographically to the central and northern parts of Guangdong Province), many small stocks occur in the southern part of Jiangxi Province. Most of the small stocks are associated closely with economically significant rare-metal deposits (W, Sn, Nb, Ta). Here we report the results for biotite granites and two-mica granites from three Yanshanian stocks of the Longyuanba complex. LA-ICPMS U-Pb dating of zircon yields an age of 156.1±2.1 Ma for Xiaomubei biotite granite, and U-Pb zircon dating using SIMS yields an age of 156.7±1.2 Ma for Longyuanba-Chengjiang biotite granite and 156.4±1.3 Ma for Jiangtoudong two-mica granite. Biotite granites are silica-rich (SiO 2 =70%-79%), potassic (K 2 O/Na 2 O>1.9), and peraluminous (ASI=1.05-1.33). Associated samples are invariably enriched in Rb, Th, Pb and LREE, yet depleted in Ba, Nb, Sr, P and Ti, and their REE pattern shows a large fractionation between LREE and HREE ((La/Yb) N =10.7-13.5) and a pronounced Eu negative anomaly (δEu=0.28-0.41). Two-mica granite samples are also silica-rich (SiO 2 =75%-79%), potassic (K 2 O/Na 2 O>1.2), and peraluminous (ASI=1.09-1.17). However, in contrast to the biotite granites, they are more enriched in Rb, Th, Pb and extremely depleted in Ba, Nb, Sr, P and Ti, and exhibit nearly flat ((La/Yb) N =0.75-1.08) chondrite-normalized REE patterns characterized by strong Eu depletion (δEu=0.02-0.04) and clear tetrad effect (TE 1.3 =1.10-1.14). Biotite granites and two-mica granties have comparable Nd isotopic signatures, and their εNd(t) are concentrated in the 13.0 to 9.6 and 11.5 to 7.7 respectively. Their zircon Hf-O isotopes of both also show similarity (biotite granites: εHf(t)=10.8-7.9, δ 18 O=7.98‰-8.89‰ and εHf(t)= 13.8 to 9.1, δ 18 O=8.31‰-10.08‰; two-mica granites: εHf(t)=11.3 to 8.0, δ 18 O=7.91‰-9.77‰). The results show that both biotite and two-mica granites were derived mainly from sedimentary source rocks with a minor contribution from mantle-derived materials. In spite of some S-type characteristics, the biotite granites were formed by fractional crystallization of I-type magma and assimilation of peraluminous sedimentary rocks during their ascent to the surface. Therefore, they belong to highly fractionated I-type granites. Two-mica granites exhibit a tetrad effect in their REE patterns, but share the same isotopic features with the biotite granites, suggesting that they are highly fractionated I-type granites as well. Their Lanthanide tetrad effects may be attributed to the hydrothermal alteration by magmatic fluids that have suffered degassing at late stages. Granitic magmas undergoing fractional crystallization and wall-rock assilimation can generate highly evolved granites with no REE tetrad effect in the uni-phase system. However, in the late-stage of magmatic evolution in the multi-phase system (i.e., magmatic-hydrothermal s...

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Stable isotope fractionation between liquid and vapour in water–salt systems up to 600°C

Cited by 131 publications

References 24 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Variations of Stable Isotope Ratios in Nature

Petrogenesis of early Yanshanian highly evolved granites in the Longyuanba area, southern Jiangxi Province: Evidence from zircon U-Pb dating, Hf-O isotope and whole-rock geochemistry

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