Geochronology 

Prehistoric volcanic eruptions are often dated by wiggle matching series of radiocarbon ages on tree rings to standard calibration curves, ignoring potential contamination by 'old' carbon given off by the volcano. We modeled the effects of low amounts of contamination on wiggle match dates for the 10th century Changbaishan eruption and found evidence of contamination in all. We propose a new protocol to identify the presence of contamination, and provide more secure dates for major eruptions.

We describe the design and performance of a new noble gas mass laboratory dedicated for the development and application to cosmogenic nuclides at the University of Cologne (Germany). At the core of the laboratory are a state-of-the-art high mass resolution multicollector Helix MCPlus (Thermo-Fisher) noble gas mass spectrometer and a novel custom-designed automated extraction line; including a laser-powered extraction furnace. Performance was tested with intercomparison (CREU-1) material.

When using trapped-charge dating methods to determine the time of deposition of a sediment, it is of great importance to know whether the signal containing the age information, has been completely erased before burial or if a residual signal is inherited. We examined the residual doses of the quartz ESR signals of young fluvial sediments from the lower Rhine terraces with known luminescence ages. We found varying but large residuals indicating an incomplete bleaching of the quartz ESR signals.

We use X-ray scanning to improve the quality of geologic ages derived from measuring the products of cosmic rays in the mineral magnetite. We show that the presence of other minerals can lead to wrong age estimates. By detecting those minerals with X-rays and analyzing only pure magnetite, this problem can be avoided. We also measure the rate at which helium from cosmic rays is produced in magnetite, which can be used for similar studies in the future.