石英—锡石—水体系氧同位素分馏作用实验研究

Experimental Studies of Oxygen Isotope Fractionation between Quartz-Cassiterite and Water

本文在400～500℃及250～370℃温度范围内,盐度为0～15wt%,压力约0.3～0.6kbar条件下,分别在水溶液中完成了由硅胶及非晶质SnO_2合成石英-锡石矿物对以及由非晶质SnO_2等合成的锡石与水之间氧同位素分馏的实验研究,获得了石英-锡石-水体系氧同位素分馏作用系数与温度的关系方程:1000lna_(石英-锡石)=3.11×10~6T^(-2)+1.63(400～500℃),1000lna_(石锡-水)=2.60×10~6T^(-2)-9.91(250～370℃±),1000lna_(锡石-水)=0.20×10~6T^(-2)-4.34(370±～500℃).

Experimental studies on isotope fractionation for oxygen between the mineral pair of quartz andcassiterite synthesized from silica gel or/and amorphous SnO_2 and the cassiterite synthesized from SnO_2and water were conducted in water solution respectively at temperature ranges 400-500℃ and250-370±-500℃, under a pressure range of 0.3-0.6 Kbar, with water salinty of 0-15wt%. Temperature variations of the isotope fractionation factor for oxygen between quartz-cassiterite and water we obtainedfrom our studies are expressed by following equations:1.1000 In a_QC_3=3.11(10~6T^(-2))+1.63 (400℃-500℃)2.1000 lna_C_5-H_3O^2=2.60(10~6T^(-2))-9.91 (250℃-37℃±)3.1000 lnaC_3-H_3O^2=0.20(10~6T_-2)-4.34 (370℃±-500℃)