Geology and Age of Solander Volcano, Fiordland, New Zealand

AbstractThe Solander Islands are the eroded remnants of a once much larger volcanic complex, the only known subduction-related magmatism on the Pacific-Australia plate boundary south of New Zealand. The largest island, Hautere, preserves an eruptive sequence of subaerial adakitic andesite domes and related block and ash flows, followed by a phase of phreatomagmatic deposits. Ar-Ar plagioclase ages, detrital U-Pb zircon ages, and magnetostratigraphic data from Hautere indicate that magmatism probably occurred in the interval 100–350 ka. In contrast, an andesite dome on nearby Little Solander Island gives an age of 20–50 ka. Local hydrothermal activity is manifested as orange-colored alteration and tuffisite dikes. There is no evidence, at least in the small preserved remnants of the Solander Islands, for tectonic uplift or subsidence; most of Solander Volcano was eroded away during Late Pleistocene marine planation.