Abstract
A columnar stalagmite from a limestone cave in the Florentine Valley, Tasmania, has been dated by three 230Th/ 234U age determinations. Continuous profiles of 170 δ 18O and δ 13C values as well as magnesium and strontium concentrations are presented. δ 18O values indicate temperatures lower than today with a gradual temperature decline in the basal part of the profile punctuated by two short cooling events and culminating in a double temperature minimum between 70 and 60 ka. The profile shows marked similarities with the GISP ice core record from Greenland which shows two short intense stadials centred on 74 and 70 ka preceding the Last Glacial temperature minimum. They have been correlated with ‘Heinrich’ events in North Atlantic marine cores which in turn have been attributed to periodic massive discharges of icebergs into the North Atlantic. The Tasmanian speleothem record suggests that these events may also have affected climates in the southern hemisphere. The δ 13C variations also appear to indicate periodic environmental change. Minor element variations were found to be significantly correlated with isotopic changes. Strontium concentrations show a bimodal distribution indicating control by a switching mechanism tentatively attributed to variations in calcitic dust supply to the ground surface above the site.
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