Abundant and complex metamorphic rocks are widespread in Sanjiang region, southeastern Tibetan plateau. Amphibole-bearing metamorphic rocks, comprising amphibolite and amphibole-bearing plagioclase gneiss, occur as lenses or thin layers within metamorphic supracrustal rocks. The geochemical characteristics are very similar to those of the island-arc basalt, indicating that the protolith of the amphibolites was formed in the subduction-collision tectonic setting. The geochemical features are inherited from those of andesitic or andesitic/basaltic rocks, indicating that the protolith of the amphibole-bearing plagioclase gneiss appeared in a plate convergence tectonic setting.oft-com:office:office" />