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| Titel |
Constraining Holocene hydrological changes in the Carpathian–Balkan region using speleothem δ18O and pollen-based temperature reconstructions |
| VerfasserIn |
V. Drăguşin, M. Staubwasser, D. L. Hoffmann, V. Ersek, B. P. Onac, D. Veres |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2014-07-22), S.1363-1380 |
| Datensatznummer |
250117017
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| Publikation (Nr.) |
 copernicus.org/cp-10-1363-2014.pdf |
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| Zusammenfassung |
Here we present a speleothem isotope record (POM2) from Ascunsă Cave
(Romania) that provides new data on past climate changes in the
Carpathian–Balkan region from 8.2 ka until the present. This paper describes an
approach to constrain the effect of temperature changes on calcite δ18O values in stalagmite POM2 over the course of the middle Holocene
(6–4 ka), and across the 8.2 and 3.2 ka rapid climate change events.
Independent pollen temperature reconstructions are used to this purpose. The
approach combines the temperature-dependent isotope fractionation of rain
water during condensation and fractionation resulting from calcite
precipitation at the given cave temperature. The only prior assumptions are
that pollen-derived average annual temperature reflects average cave
temperature, and that pollen-derived coldest and warmest month temperatures
reflect the range of condensation temperatures of rain above the cave site.
This approach constrains a range of values between which speleothem δ18O changes should be found if controlled only by surface temperature
variations at the cave site. Deviations of the change in δ18Ocspel values from the calculated temperature-constrained
range of change are interpreted towards large-scale variability of
climate–hydrology.
Following this approach, we show that an additional ∼0.6‰
enrichment of δ18Oc in the POM2 stalagmite was caused
by changing hydrological patterns in SW Romania across the middle Holocene,
most likely comprising local evaporation from the soil and an increase in
Mediterranean moisture δ18O. Further, by extending the calculations
to other speleothem records from around the entire Mediterranean basin, it
appears that all eastern Mediterranean speleothems recorded a similar
isotopic enrichment due to changing hydrology, whereas all changes recorded
in speleothems from the western Mediterranean are fully explained by
temperature variation alone. This highlights a different hydrological
evolution between the two sides of the Mediterranean.
Our results also demonstrate that during the 8.2 ka event, POM2 stable
isotope data essentially fit the temperature-constrained isotopic
variability. In the case of the 3.2 ka event, an additional climate-related
hydrological factor is more evident. This implies a different rainfall
pattern in the Southern Carpathian region during this event at the end of the
Bronze Age. |
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