Oxygen isotope fractionation between hydroxide minerals and water

The modified increment method has been applied to the calculation of oxygen isotope fractionation factors for hydroxide minerals. The results suggest the following sequence of ¹⁸O-enrichment in the common hydroxides: limonite > gibbsite > goethite > brucite > diaspore. The hydroxides are significantly enriched in ¹⁸O relative to the corresponding oxides. The sequence of ¹⁸O-enrichment in the hydroxides and oxides of trivalent cations is as follows: M(OH)₃ > MO(OH) > M₂O₃. There are also considerable fractionations within the polymorphos of Al(OH)₃. The internally consistent fractionation factors for hydroxide–water systems are obtained for the temperature range of 0 to 1200 °C, which are comparable with the data derived from synthesis experiments and natural samples at surficial temperatures. Temperature dependence of oxygen isotope fractionations between goethite, gibbsite, boehmite and diaspore and water are significant enough for the purpose of geothermometry. Thus the hydroxide–water pairs hold great promise of serving as reliable paleothermometers in surficial geological environments. Received: 22 January 1997 / Revised, accepted: 2 June 1997     

电气石和水之间的氢同位素分馏

作者对电气-水体系氢同位素平衡分馏和动力学分馏和动力学分馏开展了实验研究，丰富了羟基矿物氢同位素分馏资料。本文对该研究的实验技术、分析方法作了介绍，并对实验结果进行讨论与国外已有的该方面的资料作了对比。在800-650℃时电气石和水之间氢同位素平衡分馏系数与温度间线性关系为103lna电气石-水=-28.24（106/T2）+2.60；交换速率常数与温度间关系为lnk2=-0.19-6.70（103/T）     

Hydrogen isotope fractionation between kaolinite and water revisited

The equilibrium hydrogen isotope fractionation factor (α) between kaolinite and water in the temperature range 330 to 0°C is 1000 In α_kaol-water = −2.2 × 10⁶T⁻² − 7.7. This monotonic expression is based on a combination of experimental data with >75% of exchange and empirical calibrations. The previously proposed and widely accepted complex fractionation expression is considered to reflect the role of surface and intersite fractionation effects in the low percent of exchange experiments(Liu and Epstein, 1984), and incorrect δD water values for the empirical values (Lambert and Epstein, 1980). There is no measurable fractionation between dickite and kaolinite. The temperature dependence of the kaolinite-water hydrogen isotope fractionation factor can probably be used as a model for other phyllosilicate-water systems below 350°C.     

Hydrogen isotope exchange between clay minerals and sea water

The D/H ratios of separated size fractions of clay minerals in two deep sea sediments taken from depths of 30 and 1100cm in a North Pacific Ocean core were measured to investigate the extent of hydrogen isotope exchange between detrital clay minerals and sea water. The D/H ratio of each size fraction of the shallower sample was compared with that of the corresponding size fraction of the deeper sample. No differences were detected between D/H ratios of corresponding size fractions from the two levels in the core except for the <0.1μm size fraction, which makes up only 5% of the sample. Even in this size fraction only about 8–28% D/H exchange is apparent. This is interpreted as indicating that no significant hydrogen isotope exchange between clay minerals and sea water has occurred during the past 2–3 Myr. Therefore information concerning the provenance and mode of formation of detrital clay minerals can be obtained from the D/H ratios of deep sea sediments younger than 2–3 Myr.     

Hydrogen and oxygen isotope exchange reactions between clay minerals and water

The extent of hydrogen and oxygen isotope exchange between clay minerals and water has been measured in the temperature range 100–350° for bomb runs of up to almost 2 years. Hydrogen isotope exchange between water and the clays was demonstrable at 100°. Exchange rates were 3–5 times greater for montmorillonite than for kaolinite or illite and this is attributed to the presence of interlayer water in the montmorillonite structure.Negligible oxygen isotope exchange occurred at these low temperatures. The great disparity in D and O¹⁸ exchange rates observed in every experiment demonstrates that hydrogen isotope exchange occurred by a mechanism of proton exchange independent of the slower process of O¹⁸ exchange.At 350° kaolinite reacted to form pyrophyllite and diaspore. This was accompanied by essentially complete D exchange but minor O¹⁸ exchange and implies that intact structural units in the pyrophyllite were inherited from the kaolinite precursor.     

Oxygen isotope fractionation between zoisite and water

Oxygen isotope fractionations between zoisite and water have been studied at 400–700°C, PH₂O = 13.4 kbar, using the three-isotope method described by Matsuhisaet al. (1978) and Matthewset al. (1983a). The zoisite-waier exchange reaction takes place extremely slowly and consequently direct-exchange calibration of equilibrium ${}^{18}\text{O}{}^{16}\text{O}$ fractionation factors was possible only at 600 and 700°C. Fractionation factors at 400–600°C were determined from samples hydrothermally crystallized from a glass of the anhydrous zoisite composition. At 600°C, both exchange procedures gave identical fractionations within experimental error. Scanning electron microscope studies showed that the zoisite-water exchange reaction occurs largely by solution-precipitation mass-transfer mechanisms. The slow kinetics of zoisite-water exchange may be typical of hydrous silicates, since additional experiments on tremolite-water and chlorite-water exchange also showed very low rates. When the zoisite-water fractionation factors determined in this study are combined with the quartz and albite-water data of Matsuhisaet al. (1979) and the calcite-water data of O'Nellet al. (1969), mineral-pair fractionations are obtained for which the coefficients “A” in the equation 1000 In α = A × 10⁶T^?2 are:

     

7.

Oxygen isotope fractionation between rutile and water   总被引：1，自引：0，他引：1  

Sunit K. Addy  G. D. Garlick 《Contributions to Mineralogy and Petrology》1974,45(2):119-121

Synthetic rutile-water fractionations (1000 ln α) at 775, 675, and 575° C were found to be ?2.8, ?3.5, and ?4.8, respectively. Partial exchange experiments with natural rutile at 575° C and with synthetic rutile at 475° C failed to yield reliable fractionations. Isotopic fractionation within the range 575–775° C may be expressed as follows: 1 $$1000\ln \alpha ({\rm T}i{\rm O}_{2 } - H_2 O) = - 4.1 \frac{{10^6 }}{{T_{k^2 } }} + 0.96$$ . Combined with previously determined quartz-water fractionations, the above data permit calibration of the quartz-rutile geothermometer: 1 $$1000\ln \alpha ({\text{S}}i{\rm O}_{2 } - Ti{\rm O}_{2 } ) = 6.6 \frac{{10^6 }}{{T_{k^2 } }} - 2.9$$ . When applied to B-type eclogites from Europe, as an example, the latter equation yields a mean equilibration temperature of 565° C.     

8.

Prediction of high-temperature oxygen isotope fractionation factors between mantle minerals     

Yong-Fei Zheng 《Physics and Chemistry of Minerals》1997,24(5):356-364

The increment method is adopted to calculate oxygen isotope fractionation factors for mantle minerals, particularly for the polymorphic phases of MgSiO₃ and Mg₂SiO₄. The results predict the following sequence of ¹⁸O-enrichment: pyroxene (Mg,Fe,Ca)₂Si₂O₆>olivine (Mg,Fe)₂SiO₄>spinel (Mg,Fe)₂SiO₄>ilmenite (Mg,Fe, Ca)SiO₃>perovskite (Mg,Fe,Ca)SiO₃. The calculated fractionations for the calcite-perovskite (CaTiO₃) system are in excellent agreement with experimental calibrations. If there would be complete isotopic equilibration in the mantle, the spinel-structured silicates in the transition zone are predicted to be enriched in ¹⁸O relative to the perovskite-structured silicates in the lower mantle but depleted in ¹⁸O relative to olivines and pyroxenes in the upper mantle. The oxygen isotope layering of the mantle would essentially result from differences in the chemical composition and crystal structure of mineral phases at different mantle depths. Assuming isotopic equilibrium on a whole earth scale, the chemical structure of the Earth's interior can be described by the following sequence of ¹⁸O-enrichment: uppr crust>lower crust>upper mantle>transition zone>lower mantle >core.     

9.

The hydrogen isotope fractionation between kaolinite and water   总被引：1，自引：0，他引：1  

Kon-Kee Liu  Samuel Epstein 《Chemical Geology》1984,46(4):335-350

Hydrogen isotope fractionation factors between kaolinite and water were determined at temperatures between 200° and 352°C. Five-gram samples of kaolinite were heated in contact with 8-mg samples of water in sealed glass reaction tubes. Under these conditions the approach to equilibrium with time will be reflected primarily in the change of the δ D in the water. Also the δ D of the hydrogen in the kaolinite will be relatively constant, subject to minor corrections. About seventy sealed vessels were heated for various times at various temperatures. During four months of heating, ～ 25% of kaolinite hydrogen exchanged with the water at 200°C, whereas 100% exchanged at 352°C. The α-values were estimated assuming equilibrium between exchanged kaolinite and water. The 10³lnα-values are estimated to be ?20, ?15, ?6 and +7 for 352°, 300°, 250° and 200°C, respectively, which are in approximate agreement with reported values previously determined at 400°C using conventional methods as well as those estimated from kaolinite in hydrothermally active systems. The curve representing the relationship between the hydrogen isotope fractionation factor for the kaolinite-water system and temperatures between 400° and 25°C is not monotonic but rather has a maximum at 200°C.     

10.

Oxygen isotope fractionation between biogenic silica and ocean water     

Kenneth Mopper 《Geochimica et cosmochimica acta》1971

     

11.

Hydrogen isotope fractionation factors between hydrous minerals and ore fluids at low temperatures: evidence from the Granny Smith gold deposit,Western Australia     

V. J. Ojala  D. I. Groves  J. R. Ridley 《Mineralium Deposita》1995,30(3-4):328-331

There are no reported experimental data on hydrogen isotope fractionation between muscovite and water at low temperatures (< 400 °C). A fractionation curve derived from extrapolation of the high temperature calibration of Suzuoki and Epstein (1976) yields 20 to 40%. higher D values than the empirical graphical calibration of Bowers and Taylor (1985) at temperatures of about 300 °C. Data from natural hydrothermal systems formed at approximately 300 °C, where D analyses are available both from fluid inclusions and alteration muscovite/sericite, support the Bowers and Taylor (1985) calibration, thus indicating smaller fractionation factors at these temperatures than suggested by extrapolations from high-temperature experimental results.     

12.

中酸性硅酸盐熔体-水体系氢同位素分馏的压力效应   总被引：1，自引：0，他引：1  

魏春生  郑永飞  赵子福  傅斌 《地球化学》2001,30(2):107-115

对0．2－2000MPa条件下钠长石熔体，钾长石熔体以及0．2－150MPa条件下流纹岩熔体－－水体系的氢同位素分馏实验数据进行了筹压拟合，发现硅酸盐熔体与水之间的氢同位素分馏存在显著的压力效应，在800，1000和1200度条件下对钠长石熔体，水体系和流夺熔体－－水体系氢同位素分馏压力方程进行的等温拟合表明，只有在特定的压力条件下才可以用钠长石熔体－水体系来近似流纹岩熔体－－水体系的氢同位素分馏行为，当压力超过临界值时，硅酸盐熔体－水体系氢同位素分馏会发生变化，本文拟合的硅酸盐熔体－水体系氢同位素分馏等值线在P－T空间的形态变化特征与矿物－水体系存在较大差异，依据流纹岩熔体与水之间氢同位素分馏的压力效应，成功地模拟了美国西部Glass Creek流纹岩δD值和水含量变化规律与岩浆去气之间的关系。     

13.

First-principles calculation of H/D isotopic fractionation between hydrous minerals and water     

Merlin Méheut  Michele Lazzeri  Etienne Balan  Francesco Mauri 《Geochimica et cosmochimica acta》2010,74(14):3874-3882

Hydrogen fractionation laws between selected hydrous minerals (brucite, kaolinite, lizardite, and gibbsite) and perfect water gas have been computed from first-principles quantum-mechanical calculations. The β-factor of each phase was calculated using the harmonic phonon dispersion curves obtained within density functional theory. All the fractionation laws show the same shape, with a minimum between 200 °C (brucite) and 500 °C (gibbsite). At low temperatures, the mineral/liquid water fractionation laws have been obtained using the experimental gas/liquid water fractionation laws. The resulting fractionation laws systematically overestimate measurements by 15‰ at low temperatures to 8‰ at ≈400 °C. Based on this general agreement, all calculated laws were empirically corrected with reference to brucite/water data. These considerations suggest that the experimental or natural calibrations by Xu and Zheng (1999) and Horita et al. (2002) (brucite/water), Gilg and Sheppard (1996) (kaolinite/water), Wenner and Taylor (1973) (lizardite/water), and in some extents Vitali et al. (2001) (gibbsite/water) are representative of equilibrium fractionations. Besides, internal isotopic fractionation of hydrogen between inner-surface and inner hydroxyl groups has been computed for kaolinite and lizardite. The obtained fractionation is large, of opposite sign for the two systems (respectively, −23‰ and +63‰ at 25 °C) and is linear in T^-2. Internal fractionation of hydrogen in TO phyllosilicates might thus be used in geothermometry.     

14.

The extent of oxygen isotope exchange between clay minerals and sea water     

Hsueh-Wen Yeh  Samuel M. Savin 《Geochimica et cosmochimica acta》1976,40(7):743-748

The extent of oxygen isotopic exchange between detrital clay minerals and sea water was investigated by analyzing $\text{O}{}^{18}\text{O}{}^{16}$ ratios of separated fine-grained size fractions of deep-sea sediments from three North Pacific ocean cores. Isotopic results were interpreted according to models based on the assumption that the extent of isotopic exchange should increase with decreasing particle size and increasing time of exchange between the sediment and sea water. The data indicate that information concerning the provenance and mode of formation of detrital clay minerals can be obtained from the $\text{O}{}^{18}\text{O}{}^{16}$ ratios of the coarser-than-0.1 μm fraction of deep-sea sediments younger than several million years and the finer-than-0.1 μm fraction of deep-sea sediments younger than several tens of thousands of years. Furthermore, if the extent of chemical reaction between detrital clays and sea water is similar to the extent of oxygen isotopic exchange, such reaction may be important in regulating the chemistry of sea water.     

15.

Hydrogen and oxygen isotope fractionation during crystallization of mirabilite and ice     

Michael K. Stewart 《Geochimica et cosmochimica acta》1974,38(1):167-172

The equilibrium fractionation factors between mirabilite (Na₂SO₄·10H₂O) and saturated sodium sulphate solution at 25°C and 0°C and between ice and 2·5 molal sodium chloride solution at ?10°C have been measured. For mirabilite, the deuterium factors are 1·017 and 1·019, and the oxygen-18 factors are 1·0014 and 1·0020 at 25°C and 0°C, respectively. For ice, the factors are 1·024 for deuterium and 1·0022 for oxygen-18 at ?10°C. These fractionation factors are used to estimate the fractionation factors between ice and mirabilite and concentrated sea water at ?10°C. It is concluded that the average binding strengths of hydrogen in ice and mirabilite are very similar.     

16.

Oxygen isotope fractionation between oxygen of different sites in illite minerals: a potential single-mineral thermometer     

A. Bechtel  S. Hoernes 《Contributions to Mineralogy and Petrology》1990,104(4):463-470

The experimental results of Hamza and Epstein mark internal oxygen isotope fractionations of hydrosilicates as potential single-mineral thermometers. In this study methodical investigations were made to determine the oxygen isotope ratios of hydroxyl groups in silicate minerals. As a reference material a commercial kaolinite was examined by vacuum extraction and by use of a modified partial fluorination technique first deseribed by Hamza and Epstein. The concordance of the results argue against oxygen isotope fractionation during dehydroxylation. Consequently, vacuum extraction can be used to determine the internal fractionation of minerals, which contain no ferrous iron. For calibration of the internal oxygen isotope fractionation, hydrothermally formed illites from the Lone Gull uranium deposit in Canada and from the Leuggern exploration drill site in Switzerland were investigated. Formation temperatures of the hydrothermal mineralization were estimated by mineral paragenesis, illite crystallinity and by oxygen isotope fractionations on coexisting mineral phases. the oxygen isotope fractionation between oxygen of different sites in several selected illites from both regions has been analysed. The results indicate a linear correlation between the illite-OH oxygen isotope fractionation and temperature. The fractionation can be expressed by the following equation:

	Ab	Cc	Zo
Q	0.50	0.50	1.56
Ab		0.00	1.06
Cc			1.06

17. Hydrogen and carbon isotope fractionation during experimental production of bacterial methane      《Organic Geochemistry》1987,11(2):115-119 This paper presents C and H isotope compositions of compounds involved in methane production by pure cultures of Methanobacterium formicicum. The C isotope compositions of the methane produced and of the residual CO2 are compared to data observed in natural conditions in marine sediments. This comparison leads to further evidence that CO2 reduction is an important mechanism for microbial generation of methane in deep marine sediments. The H isotope compositions show involvment of the water hydrogen into methane as well as hydrogen exchange between water and molecular hydrogen in the course of CO2 reduction. A mechanism is proposed as a possible explanation for the data obtained involving conjugated reactions of CO2-reduction and enzymatic reduction of water.      18. Hydrogen isotope composition of deep-seated water   总被引：3，自引：0，他引：3   Yoshimasu Kuroda  Tetsuro Suzuoki  Sadao Matsuo 《Contributions to Mineralogy and Petrology》1977,60(3):311-315 D/H ratios of phlogopites and amphiboles from rocks of possible mantle origin and also those of water from (glass?) inclusions in olivines of the olivine nodule and peridotites have been determined. The mantle water seems to have aδD value of —85±10‰ on the basis of results of inclusions in the nodule-olivine.      19. 文石—水体系氧同位素分馏机理的实验研究   总被引：3，自引：1，他引：3   周根陶  郑永飞 《地球化学》1999,28(6):521-533 采用“附晶生长法”分别在５０和７０℃下合成文石下矿物,获得了两种不同的文石与水之间的氧同位素分馏关系。结果证明,文石与水之间氧同位素分馏的化学动力学机 为两步：（１）碳酸根与水之间进行氧同位素交换和平衡,即：「Ｃ＾１６Ｏ３」＾＾３－＋２Ｈ２＾１８Ｏ＝「Ｃ＾１８Ｏ３＾１６Ｏ」＾２－＋２Ｈ２Ｏ１６Ｏ;（２）与水平衡以后的「ＣＯ２」＾２－离子与Ｃａ＾２＋结合生成文石,即：Ｃａ＾２＋＋＿「Ｃ＾１８Ｏ２＾１      20. Oxygen isotope fractionation between synthetic aragonite and water: Influence of temperature and Mg concentration      Sang-Tae Kim  James R. O’Neil  Alfonso Mucci 《Geochimica et cosmochimica acta》2007,71(19):4704-4715 Aragonite was precipitated in the laboratory at 0, 5, 10, 25, and 40 °C to determine the temperature dependence of the equilibrium oxygen isotope fractionation between aragonite and water. Forced CO2 degassing, passive CO2 degassing, and constant addition methods were employed to precipitate aragonite from supersaturated solutions, but the resulting aragonite-water oxygen isotope fractionation was independent of the precipitation method. In addition, under the experimental conditions of this study, the effect of precipitation rate on the oxygen isotope fractionation between aragonite and water was almost within the analytical error of ±∼0.13‰ and thus insignificant. Because the presence of Mg2+ ions is required to nucleate and precipitate aragonite from Na-Ca-Cl-HCO3 solutions under these experimental conditions, the influence of the total Mg2+ concentration (up to ∼0.9 molal) on the aragonite-water oxygen isotope fractionation was examined at 25 °C. No significant Mg2+ ion effect, or oxygen isotope salt effect, was detected up to 100 mmolal total Mg2+ but a noticeable isotope salt effect was observed at ∼0.9 molal total Mg2+.On the basis of results of the laboratory synthesis experiments, a new expression for the aragonite-water fractionation is proposed over the temperature range of 0-40 °C: 1000lnαaragonite-water=17.88±0.13(103/T)-31.14±0.46

Oxygen isotope fractionation between rutile and water

Synthetic rutile-water fractionations (1000 ln α) at 775, 675, and 575° C were found to be ?2.8, ?3.5, and ?4.8, respectively. Partial exchange experiments with natural rutile at 575° C and with synthetic rutile at 475° C failed to yield reliable fractionations. Isotopic fractionation within the range 575–775° C may be expressed as follows: 1 $$1000\ln \alpha ({\rm T}i{\rm O}_{2 } - H_2 O) = - 4.1 \frac{{10^6 }}{{T_{k^2 } }} + 0.96$$ . Combined with previously determined quartz-water fractionations, the above data permit calibration of the quartz-rutile geothermometer: 1 $$1000\ln \alpha ({\text{S}}i{\rm O}_{2 } - Ti{\rm O}_{2 } ) = 6.6 \frac{{10^6 }}{{T_{k^2 } }} - 2.9$$ . When applied to B-type eclogites from Europe, as an example, the latter equation yields a mean equilibration temperature of 565° C.     

Prediction of high-temperature oxygen isotope fractionation factors between mantle minerals

The increment method is adopted to calculate oxygen isotope fractionation factors for mantle minerals, particularly for the polymorphic phases of MgSiO₃ and Mg₂SiO₄. The results predict the following sequence of ¹⁸O-enrichment: pyroxene (Mg,Fe,Ca)₂Si₂O₆>olivine (Mg,Fe)₂SiO₄>spinel (Mg,Fe)₂SiO₄>ilmenite (Mg,Fe, Ca)SiO₃>perovskite (Mg,Fe,Ca)SiO₃. The calculated fractionations for the calcite-perovskite (CaTiO₃) system are in excellent agreement with experimental calibrations. If there would be complete isotopic equilibration in the mantle, the spinel-structured silicates in the transition zone are predicted to be enriched in ¹⁸O relative to the perovskite-structured silicates in the lower mantle but depleted in ¹⁸O relative to olivines and pyroxenes in the upper mantle. The oxygen isotope layering of the mantle would essentially result from differences in the chemical composition and crystal structure of mineral phases at different mantle depths. Assuming isotopic equilibrium on a whole earth scale, the chemical structure of the Earth's interior can be described by the following sequence of ¹⁸O-enrichment: uppr crust>lower crust>upper mantle>transition zone>lower mantle >core.     

The hydrogen isotope fractionation between kaolinite and water

Hydrogen isotope fractionation factors between kaolinite and water were determined at temperatures between 200° and 352°C. Five-gram samples of kaolinite were heated in contact with 8-mg samples of water in sealed glass reaction tubes. Under these conditions the approach to equilibrium with time will be reflected primarily in the change of the δ D in the water. Also the δ D of the hydrogen in the kaolinite will be relatively constant, subject to minor corrections. About seventy sealed vessels were heated for various times at various temperatures. During four months of heating, ～ 25% of kaolinite hydrogen exchanged with the water at 200°C, whereas 100% exchanged at 352°C. The α-values were estimated assuming equilibrium between exchanged kaolinite and water. The 10³lnα-values are estimated to be ?20, ?15, ?6 and +7 for 352°, 300°, 250° and 200°C, respectively, which are in approximate agreement with reported values previously determined at 400°C using conventional methods as well as those estimated from kaolinite in hydrothermally active systems. The curve representing the relationship between the hydrogen isotope fractionation factor for the kaolinite-water system and temperatures between 400° and 25°C is not monotonic but rather has a maximum at 200°C.     

Hydrogen isotope fractionation factors between hydrous minerals and ore fluids at low temperatures: evidence from the Granny Smith gold deposit,Western Australia

There are no reported experimental data on hydrogen isotope fractionation between muscovite and water at low temperatures (< 400 °C). A fractionation curve derived from extrapolation of the high temperature calibration of Suzuoki and Epstein (1976) yields 20 to 40%. higher D values than the empirical graphical calibration of Bowers and Taylor (1985) at temperatures of about 300 °C. Data from natural hydrothermal systems formed at approximately 300 °C, where D analyses are available both from fluid inclusions and alteration muscovite/sericite, support the Bowers and Taylor (1985) calibration, thus indicating smaller fractionation factors at these temperatures than suggested by extrapolations from high-temperature experimental results.     

中酸性硅酸盐熔体-水体系氢同位素分馏的压力效应

对0．2－2000MPa条件下钠长石熔体，钾长石熔体以及0．2－150MPa条件下流纹岩熔体－－水体系的氢同位素分馏实验数据进行了筹压拟合，发现硅酸盐熔体与水之间的氢同位素分馏存在显著的压力效应，在800，1000和1200度条件下对钠长石熔体，水体系和流夺熔体－－水体系氢同位素分馏压力方程进行的等温拟合表明，只有在特定的压力条件下才可以用钠长石熔体－水体系来近似流纹岩熔体－－水体系的氢同位素分馏行为，当压力超过临界值时，硅酸盐熔体－水体系氢同位素分馏会发生变化，本文拟合的硅酸盐熔体－水体系氢同位素分馏等值线在P－T空间的形态变化特征与矿物－水体系存在较大差异，依据流纹岩熔体与水之间氢同位素分馏的压力效应，成功地模拟了美国西部Glass Creek流纹岩δD值和水含量变化规律与岩浆去气之间的关系。     

First-principles calculation of H/D isotopic fractionation between hydrous minerals and water

Hydrogen fractionation laws between selected hydrous minerals (brucite, kaolinite, lizardite, and gibbsite) and perfect water gas have been computed from first-principles quantum-mechanical calculations. The β-factor of each phase was calculated using the harmonic phonon dispersion curves obtained within density functional theory. All the fractionation laws show the same shape, with a minimum between 200 °C (brucite) and 500 °C (gibbsite). At low temperatures, the mineral/liquid water fractionation laws have been obtained using the experimental gas/liquid water fractionation laws. The resulting fractionation laws systematically overestimate measurements by 15‰ at low temperatures to 8‰ at ≈400 °C. Based on this general agreement, all calculated laws were empirically corrected with reference to brucite/water data. These considerations suggest that the experimental or natural calibrations by Xu and Zheng (1999) and Horita et al. (2002) (brucite/water), Gilg and Sheppard (1996) (kaolinite/water), Wenner and Taylor (1973) (lizardite/water), and in some extents Vitali et al. (2001) (gibbsite/water) are representative of equilibrium fractionations. Besides, internal isotopic fractionation of hydrogen between inner-surface and inner hydroxyl groups has been computed for kaolinite and lizardite. The obtained fractionation is large, of opposite sign for the two systems (respectively, −23‰ and +63‰ at 25 °C) and is linear in T^-2. Internal fractionation of hydrogen in TO phyllosilicates might thus be used in geothermometry.     

The extent of oxygen isotope exchange between clay minerals and sea water

The extent of oxygen isotopic exchange between detrital clay minerals and sea water was investigated by analyzing $\text{O}{}^{18}\text{O}{}^{16}$ ratios of separated fine-grained size fractions of deep-sea sediments from three North Pacific ocean cores. Isotopic results were interpreted according to models based on the assumption that the extent of isotopic exchange should increase with decreasing particle size and increasing time of exchange between the sediment and sea water. The data indicate that information concerning the provenance and mode of formation of detrital clay minerals can be obtained from the $\text{O}{}^{18}\text{O}{}^{16}$ ratios of the coarser-than-0.1 μm fraction of deep-sea sediments younger than several million years and the finer-than-0.1 μm fraction of deep-sea sediments younger than several tens of thousands of years. Furthermore, if the extent of chemical reaction between detrital clays and sea water is similar to the extent of oxygen isotopic exchange, such reaction may be important in regulating the chemistry of sea water.     

Hydrogen and oxygen isotope fractionation during crystallization of mirabilite and ice

The equilibrium fractionation factors between mirabilite (Na₂SO₄·10H₂O) and saturated sodium sulphate solution at 25°C and 0°C and between ice and 2·5 molal sodium chloride solution at ?10°C have been measured. For mirabilite, the deuterium factors are 1·017 and 1·019, and the oxygen-18 factors are 1·0014 and 1·0020 at 25°C and 0°C, respectively. For ice, the factors are 1·024 for deuterium and 1·0022 for oxygen-18 at ?10°C. These fractionation factors are used to estimate the fractionation factors between ice and mirabilite and concentrated sea water at ?10°C. It is concluded that the average binding strengths of hydrogen in ice and mirabilite are very similar.     

Oxygen isotope fractionation between oxygen of different sites in illite minerals: a potential single-mineral thermometer

The experimental results of Hamza and Epstein mark internal oxygen isotope fractionations of hydrosilicates as potential single-mineral thermometers. In this study methodical investigations were made to determine the oxygen isotope ratios of hydroxyl groups in silicate minerals. As a reference material a commercial kaolinite was examined by vacuum extraction and by use of a modified partial fluorination technique first deseribed by Hamza and Epstein. The concordance of the results argue against oxygen isotope fractionation during dehydroxylation. Consequently, vacuum extraction can be used to determine the internal fractionation of minerals, which contain no ferrous iron. For calibration of the internal oxygen isotope fractionation, hydrothermally formed illites from the Lone Gull uranium deposit in Canada and from the Leuggern exploration drill site in Switzerland were investigated. Formation temperatures of the hydrothermal mineralization were estimated by mineral paragenesis, illite crystallinity and by oxygen isotope fractionations on coexisting mineral phases. the oxygen isotope fractionation between oxygen of different sites in several selected illites from both regions has been analysed. The results indicate a linear correlation between the illite-OH oxygen isotope fractionation and temperature. The fractionation can be expressed by the following equation:

Hydrogen and carbon isotope fractionation during experimental production of bacterial methane

This paper presents C and H isotope compositions of compounds involved in methane production by pure cultures of Methanobacterium formicicum. The C isotope compositions of the methane produced and of the residual CO₂ are compared to data observed in natural conditions in marine sediments. This comparison leads to further evidence that CO₂ reduction is an important mechanism for microbial generation of methane in deep marine sediments. The H isotope compositions show involvment of the water hydrogen into methane as well as hydrogen exchange between water and molecular hydrogen in the course of CO₂ reduction. A mechanism is proposed as a possible explanation for the data obtained involving conjugated reactions of CO₂-reduction and enzymatic reduction of water.     

Hydrogen isotope composition of deep-seated water

D/H ratios of phlogopites and amphiboles from rocks of possible mantle origin and also those of water from (glass?) inclusions in olivines of the olivine nodule and peridotites have been determined. The mantle water seems to have aδD value of —85±10‰ on the basis of results of inclusions in the nodule-olivine.     

文石—水体系氧同位素分馏机理的实验研究

采用“附晶生长法”分别在５０和７０℃下合成文石下矿物,获得了两种不同的文石与水之间的氧同位素分馏关系。结果证明,文石与水之间氧同位素分馏的化学动力学机 为两步：（１）碳酸根与水之间进行氧同位素交换和平衡,即：「Ｃ＾１６Ｏ３」＾＾３－＋２Ｈ２＾１８Ｏ＝「Ｃ＾１８Ｏ３＾１６Ｏ」＾２－＋２Ｈ２Ｏ１６Ｏ;（２）与水平衡以后的「ＣＯ２」＾２－离子与Ｃａ＾２＋结合生成文石,即：Ｃａ＾２＋＋＿「Ｃ＾１８Ｏ２＾１     

Oxygen isotope fractionation between synthetic aragonite and water: Influence of temperature and Mg concentration

Aragonite was precipitated in the laboratory at 0, 5, 10, 25, and 40 °C to determine the temperature dependence of the equilibrium oxygen isotope fractionation between aragonite and water. Forced CO₂ degassing, passive CO₂ degassing, and constant addition methods were employed to precipitate aragonite from supersaturated solutions, but the resulting aragonite-water oxygen isotope fractionation was independent of the precipitation method. In addition, under the experimental conditions of this study, the effect of precipitation rate on the oxygen isotope fractionation between aragonite and water was almost within the analytical error of ±∼0.13‰ and thus insignificant. Because the presence of Mg²⁺ ions is required to nucleate and precipitate aragonite from Na-Ca-Cl-HCO₃ solutions under these experimental conditions, the influence of the total Mg²⁺ concentration (up to ∼0.9 molal) on the aragonite-water oxygen isotope fractionation was examined at 25 °C. No significant Mg²⁺ ion effect, or oxygen isotope salt effect, was detected up to 100 mmolal total Mg²⁺ but a noticeable isotope salt effect was observed at ∼0.9 molal total Mg²⁺.On the basis of results of the laboratory synthesis experiments, a new expression for the aragonite-water fractionation is proposed over the temperature range of 0-40 °C:

1000lnα_{aragonite-water}=17.88±0.13(10³/T)-31.14±0.46