Igneous and metamorphic petrology of lavas and dykes of the Macquarie Island ophiolite complex.

Abstract

Macquarie Island is an emergent part of the Macquarie Ridge, which runs south from New Zealand to join the Indian-Pacific ridge system, and marks the boundary between the Indian-Australian and the Pacific plates. Most of Macquarie Island is composed of fault-bounded blocks of volcanic rocks that are commonly basaltic pillow lavas with rarer massive flows and minor sediments. The sediments range from Globigerina oozes and red siltstones through coarser lithic wackes to agglomerates. Dolerite dyke swarms, gabbroic masses including a layered complex, and serpentinized peridotites also occur in the northern part of the island, where an oceanic lithosphere section has been recognized.