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| Titel |
Characteristics of annual laminae in speleothem from Grotte de Rolande, SW France and relationships to seasonal changes in the cave and surface environment. |
| VerfasserIn |
R. Kirk, D. Mattey, C. Collister |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068781
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| Zusammenfassung |
| Speleothems provide important information on past climate conditions and the multiple
proxies they contain preserve different relationships to climatic change at seasonal to
multiannual timescales from different cave environments. The Grotte de Rolande (GdR)
located near Montcuq, Lot Department, SW France is a 700m horizontal vadose passage
situated on a plateau with a single opening that enters through a roof fissure. The local
climate shows strong seasonality in temperature with moderate annual rainfall unevenly
distributed across the year. The cave has been continuously monitored for CO2,temperature
and driprate in relation to surface weather since 2009. Drip rates vary regularly with season
and reach a maximum in late winter. Cave air CO2concentrations remain relatively high
and vary from 5000-9000 ppm, reaching maximum values in late summer. Winter
cave air variations are more complex as a result of thermal instability in the cave
under winter conditions. Spelothem calcite obtained by coring the central axis of
actively growing stalagmites from GdR reveals strongly developed paired laminae
composed of transparent sparry and white fine grained calcite 150-400 microns thick. In
this study we have performed high resolution analysis of stable isotopes and trace
elements to characterise seasonal responses in isotopes and trace elements and their
relationships to the fabric and composition of speleothem laminae, the local cave
environment and surface weather. The roles of seasonal variations in driprate versus cave
air CO2 in controlling degassing rates and fabric development will be examined. |
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