1995 年 90 巻 12 号 p. 413-418
The isotope geochemical study for Iceland is reviewed. Iceland yields not only tholeiitic basalts but also tholeiitic andesites or rhyolites. Many geochemical studies were done to decipher the origin of the felsic volcanic rock which constitutes about 10% of the Icelandic crust. However, the origin was not clear. To solve this problem, the combination of Sr, Nd, Pb, He and O isotope tracers with U-Th disequilibrium has been attempted, and the involvement of the Icelandic hydrothermally altered crust into the source of the felsic rock is infered. In near future, application of new Li and B tracers will constrain the origin of the felsic rock in more detail.