Heidelberg 2015 – wissenschaftliches Programm
UP 13.15: Poster
Donnerstag, 26. März 2015, 10:45–19:45, G/Foyer
High precision U-series dating of stalagmites — •Jennifer Arps1, René Eichstädter1, François Thil2, and Edwige Pons-Branchu2 — 1Institut für Umweltphysik, Heidelberg, Germany — 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif-sur-Yvette, France
U/Th dating has become a major tool in geochronology to determine the age of secondary carbonates such as corals and stalagmites. The method is based on the radioactive disequilibrium between 238U and its decay products 234U and 230Th in natural sedimentary deposits.
With the advent of new mass spectrometer generations the precision of age determinations as well as the sample throughput can be strongly improved, which is crucial for climate studies, and provides new tracers such as the U isotopic composition of drip water.
Here, we explore the possibility to achieve є precision on stalagmites with high uranium contents using multi-collector inductively coupled plasma source mass spectrometry, whereas the challenge is to overcome the important abundance difference between uranium and thorium isotopes (in the order of 10−4 to 10−6). First results obtained at the MC-ICPMS facility of the Laboratoire des Sciences du Climate et de L’Environnement (Gif-sur-Yvette, France) will be presented.
Ultimately we seek sub-decadal time resolution for archives as young as 2000 years, to test hypothesis on the trace of ’winter’ climate change in speleothems during the Roman Migration Period (300-500 AD).