Speleothem

Description

Speleothems (cave mineral) are secondary mineral deposits that are formed by moisture in cavities. The term speleothems covers mineral deposits in caves and is therefore not limited to stalactites. Speleothems also exist in mines and similar caves where minerals, in this case carbonate, are deposited by transport with water. Especially stalactites are important for climate history, because their water-dependent deposits form a highly resolved archive. The seasonal fluctuations in water availability and origin can be reconstructed using the stable isotope ¹⁸O (more precisely: using the ¹⁸O/¹⁶O ratio). A temporal correlation is obtained by additional radiocarbon measurements.

Sample properties

For carbonates there are no special requirements for sample composition. One should be aware that samples in powder form do not allow additional cleaning steps as they dissolve very quickly. Therefore, a sample sent as powder should have been cleaned before sampling.

¹⁴C-Dating

Significantly more material is required for radiocarbon dating, since 1 mg carbon is needed for the measurement and only about 10% is present in the carbonate. Sample amounts between 50-100 mg are sufficient to allow a cleaning step if necessary (unless for powders). Please contact the laboratory if the sample quantities are much smaller.

Oxygen isotope analysis

For a determination of the ¹⁸O/¹⁶O ratio (short δ¹⁸O) less than 1mg of the carbonate in the form of powder is needed. However, the surface should already be cleaned.