Enriched End-member of Primitive MORB Melts: Petrology and Geochemistry of Glasses from Macquarie Island (SW Pacific)

Macquarie Island is an exposure above sea-level of part of the crest of the Macquarie Ridge. The ridge marks the Australia-Pacific plate boundary south of New Zealand, where the plate boundary has evolved progressively since Eocene times from an oceanic spreading system into a system of long transform faults linked by short spreading segments, and currently into a right-lateral strike-slip plate boundary. The rocks of Macquarie Island were formed during spreading at this plate boundary in Miocene times, and include intrusive rocks (mantle and cumulate peridotites, gabbros, sheeted dolerite dyke complexes), volcanic rocks (N- to E-MORB pillow lavas, picrites, breccias, hyaloclastites), and associated sediments. A set of Macquarie Island basaltic glasses has been analysed by electron microprobe for major elements, S, Cl and F; by Fourier transform infrared spectroscopy for H