Comparison of the whole rock geochemical compositions of 142 samples of Otago Schist with greywackes and argillites from the Caples and Torlesse terranes confirms the essentially isochemical nature of Otago Schist metamorphism and permits correlation of individual schist samples to each terrane. These correlations, along with lithological, structural and petrographical information, have been used to establish a preliminary position for the long-sought-after Caples-Torlesse terrane boundary in the Otago Schist.
The boundary has been involved in Late Mesozoic and Cenozoic deformation, follows a sinuous course near the schist axis for some 350 km between Dunedin and the Barrier Range and divides the Aspiring lithologic association into Caples and Torlesse parts. A number of pods of ultramafic schist are exposed in the vicinity of the terrane boundary. The methods used in this paper may have application to the location of terrane boundaries in major schist belts elsewhere.