Late glacial and Holocene climate change in the subantarctic Auckland Islands
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Date
2017-12-14
Journal Title
Journal ISSN
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Publisher
American Geophysical Union (AGU)
Abstract
Situated within the core of the Southern Hemisphere westerly winds, and between the subtropical and subantarctic fronts, the New Zealand subantarctic islands are uniquely positioned to evaluate past ocean and atmospheric change in the middle to high southern latitudes. We collected a series of sediment cores from Auckland Island fjords to produce a high-resolution record of climate change following the Last Glacial Maximum. Physical property and organic geochemical data, Itrax XRF, and visual core descriptions indicate the cores capture several phases of sedimentation. From these studies, we identify four primary sedimentary facies: 1) a deglacial facies exhibiting mm-scale laminae defined by magnetic susceptibility and density contrasts and high counts of elements associated with terrigenous sources; 2) a lacustrine facies defined by very low density, high organic carbon concentrations and low counts of lithophilic elements; 3) a marine transgression facies with moderate density, moderate bioturbation and alternating marine and lacustrine sedimentary components; 4) a marine facies that contains biogenic carbonate. Radiocarbon results indicate deglacial sedimentation was underway in the basin by approximately 19,000 cal yr BP. Lacustrine deposition in ice-free conditions began around 15,600 cal yr BP and continued until marine transgression at approximately 9,500 cal yr BP. During the early Holocene between 11 and 9.5 ka, we observe elevated n-alkane δD values and an overall increase in redox-sensitive elements that signal a combination of warmer atmospheric temperatures and reduced westerly wind strength that drives fjord stratification. Poleward-shifted westerlies south of the Auckland Islands could accommodate these results, but there are few records to corroborate this interpretation. We will discuss these results within the context of developing New Zealand and subantarctic paleoclimate records in order to provide a more comprehensive record of past change.
Description
Paper was not presented at Conference - marked Withdrawn on website.
Keywords
Climate models, Climates, Climatic change, Atmospheric circulation, Oceanography, Biogeochemistry, Quaternary period, New Zealand
Citation
Gilmer, G., Moy, C. M., Vandergoes, M., Gadd, P., Riesselman, C. R., Jacobsen, G. E., Wilson, G. S. & Visinand, C. (2017). Late glacial and Holocene climate change in the subantarctic Auckland Islands. In AGU Fall Meeting Abstracts, New Orleans, Louisiana, 11 to 15 December 2017. Retrieved from: https://agu.confex.com/agu/fm17/meetingapp.cgi/Paper/268508