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| Titel |
Stable isotopes in caves over altitudinal gradients: fractionation behaviour and inferences for speleothem sensitivity to climate change |
| VerfasserIn |
V. E. Johnston, A. Borsato, Christoph Spötl, S. Frisia, R. Miorandi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 1 ; Nr. 9, no. 1 (2013-01-22), S.99-118 |
| Datensatznummer |
250017427
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| Publikation (Nr.) |
 copernicus.org/cp-9-99-2013.pdf |
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| Zusammenfassung |
| The interpretation of stable isotope ratios in
speleothem calcite is complex, and only in a few cases, unequivocal
relationships with palaeoclimate parameters have
been attained. A major issue is temperature, which has an
effect on both the isotope incorporation into calcite and on
environmental processes. Here, a field approach is taken, by
studying the isotopic composition of calcites from monitored
caves located in steep altitudinal topography in the northern
Italian Alps. These create a thermal gradient (3–12 °C) apt
to study the effects of temperature on the speleothem isotope
record. Our data indicate that the magnitude of oxygen
isotope disequilibrium effects, calculated as an offset
from the experimentally determined equilibrium, decreases
with increased elevation (cooler temperatures) and faster drip
rate. Carbon isotope values exhibit 13C enrichment at high
altitudes (colder temperatures) and slow drip rates. The results
obtained support modelling and laboratory cave analogue
experiments that indicate temperature, drip rate, pCO2
and supersaturation are important factors controlling stable
isotope fractionation, but also stress the significance of ventilation
and evaporation in the cave environment. It is proposed
that the effects on stable isotope ratios observed along
the altitudinal gradient can be analogues for glacial to interglacial
temperature changes in regions which were extensively
glaciated in the past. |
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