Orchard, A. C.2025-08-122025-08-122023https://hdl.handle.net/2440/146731This item is only available electronically. Whole thesis (as available).The Southern Westerly Winds exert a dominant control on modern precipitation patterns in New Zealand. However, their location has not been constant throughout the geological past, appearing to migrate in relation to temperatures at the poles. Understanding past patterns of migration is, therefore, key to characterising potential shifts associated with anthropogenic warming. There is a lack of palaeoclimate records in the landmass poor Pacific region able to resolve such migrations. This thesis presents a lacustrine sedimentary record of palaeohydroclimate variability inferred from Lake Pupuke, Auckland, New Zealand, from 47 to 35 ka. These sediments also host direct evidence for the Laschamps Excursion at ~41.5 ka, a significant weakening of the Earth’s magnetic field. The Laschamps Excursion has been proposed to have had a profound impact on Earth’s climate and ecosystems, however no evidence for such an effect was found in the Lake Pupuke sediments. In terms of the hydroclimate, variations in δ18O inferred from biogenic silica suggest a teleconnection between Southern Westerly Wind driven precipitation and Antarctic temperatures such that cold periods caused a northward shift in the westerlies, thereby increasing precipitation over Auckland and vice versa. Cold and wet periods occur between 45-44 ka and 43.5-42 ka while warm and dry periods occur between 44-43.5 and 40-38 ka. These results indicate the sensitivity of the Southern Westerly Winds and, by extension, precipitation in New Zealand to global temperature shifts.enHonoursGeologyoxygen isotopesbiogenic silicaSouthern Westerly WindsNew ZealandpalaeoclimateLake PupukeThesis