Metamorphism of Granite Rocks by Olivine Dolerite in Central Australia

Abstract

A zone of intense metamorphism extends for six feet on both sides of a nearly vertical fifteen feet wide olivine dolerite dyke. Adamellites have been converted in situ to rocks resembling quartz porphyries, and mobilization of cordierite gneiss has been effected. Petrography and chemical analyses show that metamorphism is not purely thermal. Although little actual fixation of doleritic “end liquors” took place in the wall rocks the cause of these remarkable contact effects is ascribed to hydrothermal activity near the “blind end” of the dyke.