Millennial scale hydroclimate variability in New Zealand during the Last Glacial Period: oxygen isotope evidence from Lake Pupuke, Auckland

Simple item page
dc.contributor.authorOrchard, A. C.
dc.contributor.schoolSchool of Physical Sciencesen
dc.date.issued2023
dc.descriptionThis item is only available electronically. Whole thesis (as available).
dc.description.abstractThe 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.
dc.description.dissertationThesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
dc.identifier.urihttps://hdl.handle.net/2440/146731
dc.language.isoen
dc.provenanceThis electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsen
dc.subjectHonours
dc.subjectGeology
dc.subjectoxygen isotopes
dc.subjectbiogenic silica
dc.subjectSouthern Westerly Winds
dc.subjectNew Zealand
dc.subjectpalaeoclimate
dc.subjectLake Pupuke
dc.titleMillennial scale hydroclimate variability in New Zealand during the Last Glacial Period: oxygen isotope evidence from Lake Pupuke, Auckland
dc.typeThesis

Files

Original bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
OrchardAC2023_Hons.pdf
Size:
4.22 MB
Format:
Adobe Portable Document Format
Download

Collections

School of Physical Sciences