Coexisting quartz, feldspar and biotite vary widely in their δ18O values and display a remarkable 18O/16O disequilibrium relation; especially, a quartz-feldspar reversal (△ 18OQUartz_feldspar< 0) exsists in the A...Coexisting quartz, feldspar and biotite vary widely in their δ18O values and display a remarkable 18O/16O disequilibrium relation; especially, a quartz-feldspar reversal (△ 18OQUartz_feldspar< 0) exsists in the Aral granite pluton of the Altay Mountains, northern Xinjiang. The 18O / 16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic fluid are evaluated by the mass balance consideration. The conventional method of discrimination between various magma derivations simply with δ18O values of either whole rock or separate minerals is misleading and unreliable. Experiments carried out by the authors show that the 18O / 16O exchange reaction is not accompanied by what geologists describe as petrological and mineralogical alteration effect. This decoupling relation implies that exchange reaction occurs at a relatively high temperature during subsolidus-postmagmatic cooling of magmas. The exchange mechanism is mainly diffusion-controlled. It is demonstrated through quantitative modelling that the hydrothermal system associated with the Aral pluton is long-lived (0.8-6 Ma), with a relatively high fluid flow rate (3 ×10-14 mol. s-1) and high W/ R ratio (0.79-6.14). This means that an intense flow and convection may exist at the midcrustal level of erogenic magmatic arcs.展开更多
To investigate the reaction between CO2-CO and wustite using the isotope exchange method at 1073, 1173, 1273, and 1373 K, the experiment apparatus was designed to simulate the fluidized bed. The chemical rate constant...To investigate the reaction between CO2-CO and wustite using the isotope exchange method at 1073, 1173, 1273, and 1373 K, the experiment apparatus was designed to simulate the fluidized bed. The chemical rate constant was estimated by considering the effect of gas phase mass transfer on the reaction. It is found that the chemical rate constant is inversely decreased with the increase in the ratio of CO2/CO by volume. The activation energy of reaction is in a linear relationship with the ratio of COs/CO by volume, and the average activation energy is 155.37 kJ/mol.展开更多
Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur Riv...Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur River region, northern Xinjiang. Isotopic exchange with meteoric water during subsolidus cooling caused strong 18O-D depletion and the remarkable nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation between coexistent minerals. <sup>18</sup>O/<sup>16</sup>O exchange kinetic effects of the three minerals are simultaneously and consistently modelled. Exsolution and microtextural reorganization of alkali feldspar, and infiltration of water have been mutually facilitated by each other. Shallow intrusion, and circulation of meteoric water throughout the pluton cool it effectively. As a result, the "heat engine" is rapidly extinguished, and the nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation is frosen.展开更多
Coexistent minerals quartz, feldspar and biotite vary widely in δ18O value and display remarkable 18O/16O disequilibrium relations in the Ertaibei granite pluton, northern Xinjiang. The 18O/16O exchange reaction defi...Coexistent minerals quartz, feldspar and biotite vary widely in δ18O value and display remarkable 18O/16O disequilibrium relations in the Ertaibei granite pluton, northern Xinjiang. The 18O/16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic water are evaluated by the mass balance consideration. The results show that the 18O/16O exchange reaction is not necessarily accompanied by what geologists describe as petrological and mineralogiesl alteration effects, indicating that the exchange reaction occurs at a comparatively high temperature during subsolidus cooling of magmas. Exchange mechanism is mainly controlled by diffusion. It is demonstrated through quantitative modelling that the hydrothermal system associated with the Ertaibei pluton lived for 0.8-3 Ma, with a fluid flow rate of 3 × 10-14 mol · s-1 and water/rock (W/R) ratio of 0.79 - 3.08. Flow path and initial heterogeneity of the exotic metamorphic fluid are modelled with the δ18Ofluid as a variable.展开更多
For an isotopic exchange reaction between two compounds, the kinetic equations have been derived by the previous authors and have been applied to the discussion on some phenomena of isotopic disequilibrium in geochemi...For an isotopic exchange reaction between two compounds, the kinetic equations have been derived by the previous authors and have been applied to the discussion on some phenomena of isotopic disequilibrium in geochemistry, such as sulfur isotopic exchanges between sulfides and sulfates in low-temperature hydrothermal solutions and oxygen isotopic exchanges between minerals or rocks and fluids. However, an intramolecular isotope展开更多
溶液中硫化物与硫代硫酸盐之间的硫同位素交换是由硫代硫酸盐中外部疏(-SH)与内部硫(-SO_3H)交换的分子内反应和硫化物(H_2S)分别与硫代硫酸盐的外部硫和内部硫交换的分子间反应所构成。利用最小二乘法拟合Uyama et al.(1985)的H_2S和...溶液中硫化物与硫代硫酸盐之间的硫同位素交换是由硫代硫酸盐中外部疏(-SH)与内部硫(-SO_3H)交换的分子内反应和硫化物(H_2S)分别与硫代硫酸盐的外部硫和内部硫交换的分子间反应所构成。利用最小二乘法拟合Uyama et al.(1985)的H_2S和硫代硫酸盐之间硫同位素交换的实验数据,不仅得到H_2S、-SH和-SO_3H之间硫同位素交换的全反应速度常数,而且还获得它们之间交换的平衡同位素分馏系数。温度从100到170℃,有 1000 In α_((H_2)S-SH)=-15.80×(10~3/T)~2+71.34×(10~3/T)—75.53 1000 In α_((SO_3)H-SH)=-3.04×(10~3/T)~2+30.89×(10~3/T)—25.00 (T的单位为K) 1000 In α_((SO_3)H-H_2S)=12.00×(10~3/T)~2—36.85×(10~3/T)+46.26在pH近中性的溶液中,H_2S和硫代硫酸盐的-SO_2H之间硫同位素交换的全反应速度常数近似为 log k_((SO_3)HH_ZS)=-5.14×(10~3/T)+10.35(T的单位为K)反应的活化能为98.4kJ/mol。将计算所获的H_2S与-SH和-SO_3H进行的硫交换速度同Giggenbach(1974b)测定的多硫化物-硫代硫酸盐的生成反应和岐化反应速度对比,表明溶液中硫化物和硫代硫酸盐之间硫同位素交换可以通过多硫化物(例如:S_3S^2、S_1S^2等等)的生成与岐化反应: 10H_2S+3S_2O_3^(2-)4S_3S^(2-)+2H^-+9H_2O和多硫化物-硫代硫酸盐的置换反应 S_nS^2+SSO_3~2S_(n-1)S^2+SO_3^(2-)进行的。展开更多
基金This research was supported by the National Natural Science Foundation of China (grant No. 49373164)the President's Funds of the Chinese Academy of Sciences
文摘Coexisting quartz, feldspar and biotite vary widely in their δ18O values and display a remarkable 18O/16O disequilibrium relation; especially, a quartz-feldspar reversal (△ 18OQUartz_feldspar< 0) exsists in the Aral granite pluton of the Altay Mountains, northern Xinjiang. The 18O / 16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic fluid are evaluated by the mass balance consideration. The conventional method of discrimination between various magma derivations simply with δ18O values of either whole rock or separate minerals is misleading and unreliable. Experiments carried out by the authors show that the 18O / 16O exchange reaction is not accompanied by what geologists describe as petrological and mineralogical alteration effect. This decoupling relation implies that exchange reaction occurs at a relatively high temperature during subsolidus-postmagmatic cooling of magmas. The exchange mechanism is mainly diffusion-controlled. It is demonstrated through quantitative modelling that the hydrothermal system associated with the Aral pluton is long-lived (0.8-6 Ma), with a relatively high fluid flow rate (3 ×10-14 mol. s-1) and high W/ R ratio (0.79-6.14). This means that an intense flow and convection may exist at the midcrustal level of erogenic magmatic arcs.
基金supported by the National Natural Science Foundation of China (Nos. 50874128 and 50834007)
文摘To investigate the reaction between CO2-CO and wustite using the isotope exchange method at 1073, 1173, 1273, and 1373 K, the experiment apparatus was designed to simulate the fluidized bed. The chemical rate constant was estimated by considering the effect of gas phase mass transfer on the reaction. It is found that the chemical rate constant is inversely decreased with the increase in the ratio of CO2/CO by volume. The activation energy of reaction is in a linear relationship with the ratio of COs/CO by volume, and the average activation energy is 155.37 kJ/mol.
文摘Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur River region, northern Xinjiang. Isotopic exchange with meteoric water during subsolidus cooling caused strong 18O-D depletion and the remarkable nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation between coexistent minerals. <sup>18</sup>O/<sup>16</sup>O exchange kinetic effects of the three minerals are simultaneously and consistently modelled. Exsolution and microtextural reorganization of alkali feldspar, and infiltration of water have been mutually facilitated by each other. Shallow intrusion, and circulation of meteoric water throughout the pluton cool it effectively. As a result, the "heat engine" is rapidly extinguished, and the nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation is frosen.
基金Project supported by the National Natural Science Foundation of China and the President's Funds of the Chinese Academy of Sciences.
文摘Coexistent minerals quartz, feldspar and biotite vary widely in δ18O value and display remarkable 18O/16O disequilibrium relations in the Ertaibei granite pluton, northern Xinjiang. The 18O/16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic water are evaluated by the mass balance consideration. The results show that the 18O/16O exchange reaction is not necessarily accompanied by what geologists describe as petrological and mineralogiesl alteration effects, indicating that the exchange reaction occurs at a comparatively high temperature during subsolidus cooling of magmas. Exchange mechanism is mainly controlled by diffusion. It is demonstrated through quantitative modelling that the hydrothermal system associated with the Ertaibei pluton lived for 0.8-3 Ma, with a fluid flow rate of 3 × 10-14 mol · s-1 and water/rock (W/R) ratio of 0.79 - 3.08. Flow path and initial heterogeneity of the exotic metamorphic fluid are modelled with the δ18Ofluid as a variable.
文摘For an isotopic exchange reaction between two compounds, the kinetic equations have been derived by the previous authors and have been applied to the discussion on some phenomena of isotopic disequilibrium in geochemistry, such as sulfur isotopic exchanges between sulfides and sulfates in low-temperature hydrothermal solutions and oxygen isotopic exchanges between minerals or rocks and fluids. However, an intramolecular isotope
文摘溶液中硫化物与硫代硫酸盐之间的硫同位素交换是由硫代硫酸盐中外部疏(-SH)与内部硫(-SO_3H)交换的分子内反应和硫化物(H_2S)分别与硫代硫酸盐的外部硫和内部硫交换的分子间反应所构成。利用最小二乘法拟合Uyama et al.(1985)的H_2S和硫代硫酸盐之间硫同位素交换的实验数据,不仅得到H_2S、-SH和-SO_3H之间硫同位素交换的全反应速度常数,而且还获得它们之间交换的平衡同位素分馏系数。温度从100到170℃,有 1000 In α_((H_2)S-SH)=-15.80×(10~3/T)~2+71.34×(10~3/T)—75.53 1000 In α_((SO_3)H-SH)=-3.04×(10~3/T)~2+30.89×(10~3/T)—25.00 (T的单位为K) 1000 In α_((SO_3)H-H_2S)=12.00×(10~3/T)~2—36.85×(10~3/T)+46.26在pH近中性的溶液中,H_2S和硫代硫酸盐的-SO_2H之间硫同位素交换的全反应速度常数近似为 log k_((SO_3)HH_ZS)=-5.14×(10~3/T)+10.35(T的单位为K)反应的活化能为98.4kJ/mol。将计算所获的H_2S与-SH和-SO_3H进行的硫交换速度同Giggenbach(1974b)测定的多硫化物-硫代硫酸盐的生成反应和岐化反应速度对比,表明溶液中硫化物和硫代硫酸盐之间硫同位素交换可以通过多硫化物(例如:S_3S^2、S_1S^2等等)的生成与岐化反应: 10H_2S+3S_2O_3^(2-)4S_3S^(2-)+2H^-+9H_2O和多硫化物-硫代硫酸盐的置换反应 S_nS^2+SSO_3~2S_(n-1)S^2+SO_3^(2-)进行的。
