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High-resolution palaeoenvironmental information from southeast Australian speleothems

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Desmarchelier, Jolyon Michael (2000) High-resolution palaeoenvironmental information from southeast Australian speleothems. PhD thesis, University of Tasmania.

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Abstract

Speleothems, chemical cave deposits such as soda-straw stalactites, stalagmites and flowstones,
have great potential as archives of high-resolution terrestrial palaeoenvironmental change at both
short and long term temporal scales. In this study temporal control is achieved using various high
precision radiometric techniques such as TIMS 230Th/234 U dating, AMS radiocarbon dating, and
210Pb excess dating, the latter two methods used to investigate contemporary speleothem material.
An additional method adopted only with certain samples, but showing considerable promise, is
autocorrelation of annual variations in speleothem minor element concentrations. 43 new TIMS
230Th/234 U speleothem age estimates from several karst areas in Tasmania are presented as a
cumulative frequency distribution and are compared with some previously published and
unpublished speleothem data from southeast Australian continent. The distribution of ages allows
some comments to be made on past environmental conditions and their effect on speleothem
growth in southeastern Australia.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to
investigate minor element variations along the whole growth axis of several speleothems. Some
soda-straw stalactites are found to contain quasi-periodical variations in their minor element
composition, in some cases it is in phase with surface ridges, ie annual banding, sometimes visible
on the surface. Measurements of the surface ridging using dendrochronological equipment allow a
temporal framework to be developed and comparisons to be made between this chronology and
one established using the annual cyclicity of certain minor elements. The chronologies agree very
closely, indicating that soda-straw stalactites can potentially provide annually resolved records.
Measurements of the minor element and stable isotope composition of flowstone material have
been taken in order to provide records of palaeoenvironmental change in areas not previously
studied in southeastern Australia using speleothems as an information source.

Item Type: Thesis (PhD)
Keywords: Stalactites and stalagmites
Copyright Holders: The Author
Copyright Information:

Copyright 2000 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s)

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2000. Includes bibliographical references

Date Deposited: 09 Dec 2014 00:05
Last Modified: 11 Mar 2016 05:54
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