Strontium isotope composition of the Bindal Batholith, Central Norwegian Caledonides

Abstract

Forkortet: A strontium isotope study of the Bindal Batholith has been carried out. The data generally do not permit precise and accurate age calculations; however, good estimates for initial Sr ratios are commonly obtained. Low initial ratios (c. 0.704-0.705) with little internal variation are present in granitoids in the southeastern part of the batholith. Rocks with intermediate initial ratios (0.705-0.710) predominate and are present throughout most of the batholith, whereas very high ratios (>0.715) are found in tourmaline granites and anatec- tic granitoids in the west. Considering a subduction related setting for the plutonism, the geographical distribution of Sr initial ratios would be consis- tent with a westward-dipping subduction zone.