Near-synchroneity of New Zealand alpine glaciations and Northern Hemisphere continental glaciations during the past 750 kyr

Abstract

The Brunhes magnetochron (0–730 kyr) at Deep Sea Drilling Project Site 594 off eastern South Island, New Zealand, comprises up to ∼100 m of alternating units of pelagic and hemipelagic ooze formed during interglacial and glacial periods respectively. The youngest hemipelagic interval corresponds to glacial isotope stage 2 and can be correlated with extensive glacial and glacio-fluvial deposits of the late Last Glaciation (∼27–13 kyr BP) on South Island. Inferring the same genetic link for the other hemipelagic sediment units down core, we show here that as many as 12 major episodes of expanded alpine glaciation have occurred on South Island in the past 730 kyr. Each of these glacial episodes coincided with a period of significant 18O enrichment (+2‰) in the core resulting from changes in ocean isotope composition associated with major growth phases of the Northern Hemisphere ice sheets. The inferred history of alpine glaciations on this remote South Pacific island appears to be closely phase-locked (±3 kyr) to world-wide climate changes.