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dc.contributor.advisorHendy, Chris H.
dc.contributor.advisorHall, Brenda L.
dc.contributor.authorCroall, Jacob Grant
dc.date.accessioned2019-09-06T02:23:37Z
dc.date.available2019-09-06T02:23:37Z
dc.date.issued2005
dc.identifier.citationCroall, J. G. (2005). Late Holocene cool climate episodes, recorded on Lake Bonney, an Antarctic amplifier lake (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/12837en
dc.identifier.urihttps://hdl.handle.net/10289/12837
dc.description.abstractChemical, stable isotope and natural abundance radionuclide analysis of cores taken through sediments below Lake Bonney, Taylor Valley, Antarctica, show evidence of multiple episodes of flooding by meltwaters from Taylor Glacier and desiccation to brines sufficiently concentrated to produce ice free conditions. The last three identified desiccation events date 1550 ± 40, 800 ± 100 and 450 ± 160 yr B.P. and match the last three periods of sustained cooling identified by isotope changes in the Taylor Dome ice core. Similar cooling events have been identified by other authors elsewhere in Antarctica. The desiccation events have produced dramatic changes in the sediment character of Lake Bonney East Lobe, but show little impact in the West Lobe. In East Lobe halite, hydrohalite, gypsum, and aragonite are precipitated and extreme isotopic enrichment of carbon (up to 813C of +12.0%0) occurred as aragonite was forced from solution by rapid freezing of the brine over winter. Reflooding events were often associated with algal blooms and resulted in radical changes in the 180/1 60 ratio in the water column. It is speculated that Taylor Glacier retreated to expose a 250 m deep subglacial depression during the last glacial maximum allowing Glacial Lake Washburn to extend westwards to perhaps Cavendish Rocks. The reduced Taylor Glacier enabled Taylor Dome to lower causing deposition of more 180 enriched ice than would otherwise have been expected. Taylor Glacier and Taylor Dome have continued to advance throughout the Holocene.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikato
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.titleLate Holocene cool climate episodes, recorded on Lake Bonney, an Antarctic amplifier lake
dc.typeThesis
thesis.degree.grantorThe University of Waikato
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (MSc)
dc.date.updated2019-09-06T02:20:38Z
pubs.place-of-publicationHamilton, New Zealanden_NZ


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