Dating of speleothems
For this reason, among others, speleothems provide more constraining dates as they record palaeomagnetic signals and can be compared to global magnetostratigraphy.However, only relative dates can be garnered from this method and direct dating of the fossils themselves is often impossible.One major aspect is modeling of processes related to carbonate precipitation in the cave environment and climate modeling on the basis of proxy records from stalagmite archives. In the marine realm we study different archives and proxys. Besides the speleothem research in the framework of DAPHNE we study in cooperation with different working groups stalagmites from different places in the world. Deep sea corals are investigated as archives of ocean circulation changes.
The difference is often explained by changes of atmospheric radiocarbon concentration in the past, and in fact, speleothems have been used as a material for radiocarbon time scale calibration.The age distribution of the speleothem samples reveals that speleothem growth ceased, or was considerably diminished, between 200 and 120 ka ago, a time corresponding to the penultimate glaciation (Oxygen-isotope Stage 6).This is consistent with observations from several other caves and suggests that conditions generally were unfavorable for speleothem formation during glacial periods.Ages obtained range from 30 to 135 ky with a hiatus between 50 and 80 ky BP.Changes in uranium isotopes activity ratios indicate a change in climatic conditions.