Late. Oligocene Pacific-wide tectonic event

Stratigraphic and structural changes, radiometrically and biostratigraphically dated, from basins and basement across New Zealand, indicate that the modern Australia-Pacific plate boundary, including the Alpine fault sector, formed between 28 and 24 Ma. This age range coincides with changes at about 25 Ma in the trends of the Hawaiian and Louisville hotspot chains, and a 27–25 Ma reorganization of spreading on the Antarctic-Pacific spreading ridge. It also follows closely the 28.5 Ma initiation of subduction of the East Pacific Rise south of Mendocino fracture zone that lead to formation of the San Andreas continental transform. The late Oligocene Pacific-wide tectonic reorganization may have been triggered by this ridge-trench collision.