100MPa、850℃和800℃条件下锡在流体与富磷过铝质熔体相间分配的实验研究

Experimental study on Sn partitioning between phosphorus-rich peraluminous melt and coexisting aqueous fluid

利用江西宜春414岩体中的钠长石花岗岩作为实验初始物,制备含不同P2O5含量(0.27%～7.71%)的实验玻璃,本次实验研究了100MPa、850℃和800℃条件下Sn在流体与富磷过铝质熔体相间的分配。实验结果显示,Sn在流体与熔体相间的分配系数(DfSlnuid/melt)变化于2.10×10-4～1.36×10-3之间,指示Sn强烈趋向于在富磷过铝质熔体中富集。随体系中P2O5含量从0.27%增至1.91%,Sn在流体与熔体相间的分配系数逐渐增加,当体系中P2O5含量进一步增加时,Sn在两相间的分配系数呈降低的趋势。本次实验结果表明,P可能不是Sn以流体相形式进行搬运的主要络合剂。

The albite granite of Yichun stock, added with 0.27% -7.71% P2o5, was chosen as the initial composition. The partition coefficients of Sn between the phosphorus-rich peraluminous granitic melt and coexisting aqueous fluid were determined at 100 MPa and 800 ℃ and 850 ℃. The experimental results show that the partition coefficients Dsofluid/melt （ Dsofluid/melt= Cfluid/Cmelt, where Cfluid and Cmelt, are the concentrations of Sn in the aqueous fluid and the melt, respectively） vary from 2. 10 × 10^-4 to 1.36 ×10^-3, indicating that Sn partitions preferentially into the hydrous melts. The partition coefficients of Sn increased with increasing P2O5 content from 0. 27% to 1.91%, but decreased when the P2O5 content further increased. According to our experimental results, P is probably not the main complexant for the transportation of Sn in fluids evolved from a granitic magma.