Abstract
Adakitic plutons dominate the Early Cretaceous igneous suite of the Kitakami Mountains of northeast Japan. The zoned plutons typically consist of adakitic granite in their centers (central facies) surrounded by adakitic to non-adakitic granites in their margins (marginal facies). The central facies granites are characterized by low Y and high Sr concentrations and fractionated LREE/HREE patterns, characteristics common to Archean TTG and modern adakite. Chemical compositions of the central facies granites can be explained by the ``slab melting'' model. The marginal facies granites are characterized by slightly lower Sr/Y ratios, less fractionated REE patterns, and weak negative Eu anomalies. The marginal facies magma is considered to be derived from the reaction of slab melts with mantle peridotite and lower crustal amphibolite.
