Detailed Paleotemperature Profiles of the High Arctic from Perennial Spring Tufa Deposits
Abstract
The Canadian High Arctic is a sensitive indicator for global climate change. As such, historical records of recent fluctuations in arctic temperature may provide insights into the effect of anthropogenic activity on global climate. Active calcite deposits from perennial springs at Expedition Fiord on western Axel Heiberg Island potentially provide a historical record of environmental conditions in the form of crusts having alternating dark (50 microns) and light (150 microns) laminae when thin sections of material are viewed in cross section under transmitted light. The laminae grow on pre-existing rip-up clasts in mineral-rich spring waters, which maintain a nearly constant temperature (6oC) and flow rate (1.3 L/s) throughout the year. High resolution isotopic records (carbon and oxygen) of mineral growth were obtained from polished thick sections (150 microns) of the crust using a computer controlled X-Y-Z micro-positioning stage to drill trenches (100 microns wide) along transects perpendicular to the accretionary laminae. Carbonate powders (approximately 75 micrograms) were collected from trenches with a microspatula and transferred to reaction vessels where they were reacted with orthophosphoric acid to produce CO2. Samples were then analyzed using the automated sampling device (GasBench) and a Delta +XL isotope ratio mass spectrometer operating in continuous flow mode. Stable isotope profiles were constructed over 50-100 laminae couplets and interpreted within the context of changing temperature regimes using the oxygen isotope paleotemperature equation for calcite.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.V22B1042R
- Keywords:
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- 1040 Isotopic composition/chemistry;
- 1610 Atmosphere (0315;
- 0325);
- 9315 Arctic region