The Luohe iron deposit is a volcano-pneumato-hydatogenetic metasomatic deposit of late Mesozoic age. In addition to magnetite, this ore deposit contains abundant pyrite and anhydrite. The temperatures of mineralizatio...The Luohe iron deposit is a volcano-pneumato-hydatogenetic metasomatic deposit of late Mesozoic age. In addition to magnetite, this ore deposit contains abundant pyrite and anhydrite. The temperatures of mineralization and alteration may he estimated from sulfur isotopic fractionation between the coexisting anhydrite and pyrite. The fact that the estimated temperatures from the weakly altered zone using the sulfate-pyrite equation of H. Ohmoto and R. O. Rye (1979) coincide with those estimated by other means (e.g. fluid inclusion), but the opposite holds true with those from the strongly altered zone indicates the establishment of isotopic equilibrium between anhydrite and pyrite in the weakly altered zone.However,assuming δ^34SAub=δ^34SSO2 and δ^34Spy=δ^34SH2S and using the SO2-H2S equation,the isotopic temperatures from the strongly altered zone are reported to be coineident with the data from fluid inclusions and one formation on.So the authors consider that there was established an equilibrium between SO2 and H2S in hydrothermal fluids during strong alteration,and the mechanisms of formation of anhydrite and pyrite in the two altered zones are probably different.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
分子内不同结构位置上两个同种元素的原子间的直接同位素交换,服从假一级化学反应速度定律。这两位置原子间的同位素交换分数 F 仅为反应时间 t 的函数,且有 ln(1—F)=-(k_f+k_(?)_t。由此分析 Uyama 等(1985)的实验结果,表明热液中硫...分子内不同结构位置上两个同种元素的原子间的直接同位素交换,服从假一级化学反应速度定律。这两位置原子间的同位素交换分数 F 仅为反应时间 t 的函数,且有 ln(1—F)=-(k_f+k_(?)_t。由此分析 Uyama 等(1985)的实验结果,表明热液中硫代硫酸盐(HSSO_3H)分子内-SO_3H 和-SH 之间的直接硫同位素交换很慢,它们之间实际存在的较快速同位素交换是通过与硫化物反应形成多硫化物这个可逆反应来实现的。展开更多
文摘The Luohe iron deposit is a volcano-pneumato-hydatogenetic metasomatic deposit of late Mesozoic age. In addition to magnetite, this ore deposit contains abundant pyrite and anhydrite. The temperatures of mineralization and alteration may he estimated from sulfur isotopic fractionation between the coexisting anhydrite and pyrite. The fact that the estimated temperatures from the weakly altered zone using the sulfate-pyrite equation of H. Ohmoto and R. O. Rye (1979) coincide with those estimated by other means (e.g. fluid inclusion), but the opposite holds true with those from the strongly altered zone indicates the establishment of isotopic equilibrium between anhydrite and pyrite in the weakly altered zone.However,assuming δ^34SAub=δ^34SSO2 and δ^34Spy=δ^34SH2S and using the SO2-H2S equation,the isotopic temperatures from the strongly altered zone are reported to be coineident with the data from fluid inclusions and one formation on.So the authors consider that there was established an equilibrium between SO2 and H2S in hydrothermal fluids during strong alteration,and the mechanisms of formation of anhydrite and pyrite in the two altered zones are probably different.
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。
文摘分子内不同结构位置上两个同种元素的原子间的直接同位素交换,服从假一级化学反应速度定律。这两位置原子间的同位素交换分数 F 仅为反应时间 t 的函数,且有 ln(1—F)=-(k_f+k_(?)_t。由此分析 Uyama 等(1985)的实验结果,表明热液中硫代硫酸盐(HSSO_3H)分子内-SO_3H 和-SH 之间的直接硫同位素交换很慢,它们之间实际存在的较快速同位素交换是通过与硫化物反应形成多硫化物这个可逆反应来实现的。
