The sea floor between New Zealand and the flanks of the Pacific-Antarctic Ridge is diversified by an extensive submarine platform, the Campbell Plateau, and a narrow arcuate ridge, the Macquarie Ridge. Campbell Plateau has a geological history extending at least to the Triassic, if not into the Precambrian. It is believed to be the extension of the Lord Howe Rise, displaced across the Alpine Fault. It formed part of the foreland for the New Zealand Mesozoic Geosyncline, was eroded to base level during the late Cretaceous, and has remained at about its present depth since the beginning of the Tertiary. Late Tertiary alkaline volcanicity is associated with elevation of rises on the plateau. Phosphatised early and mid-Tertiary foraminiferal oozes from parts of the Campbell Plateau indicate that this type of sediment has been deposited here continually since the end of the Cretacoeous. Authigenic glauconite, phosphorite, and manganese minerals are found locally on the plateau surface. [...] |
