Hannover 2010 – wissenschaftliches Programm

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SYMS: Symposium New methods of mass spectroscopy and their application in the environmental science

SYMS 2: Session II

SYMS 2.3: Hauptvortrag

Donnerstag, 11. März 2010, 15:00–15:30, A 001

Precise and accurate analysis of U-series isotopes by MC-ICPMS — •Denis Scholz — Institut für Geowissenschaften, Johannes-Gutenberg-Universität Mainz, Germany

The reconstruction of past climate variability provides important information for the determination of the magnitude of both temporal and spatial natural climate variability. Furthermore, paleoclimate data provide constraints for climate model simulations and may also be used to validate the predictions of those.

An important issue of paleoclimate reconstruction is the precise determination of the timing and duration of past climate changes. One of the most precise dating methods for the period of the last 600,000 years is Th/U-dating. The application of MC-ICPMS allows both very precise and accurate determination of U-series isotope ratios, high sample throughput, and to work with small sample sizes.

However, the raw isotope ratios measured by MC-ICPMS are affected by several instrumental biases, such as ion-counter-Faraday-cup gain, ion counter darknoise, Faraday cup baseline, peak tailing ("abundance sensitivity") and mass fractionation, which need to be corrected. In this talk I will discuss these various effects and outline appropriate correction methods.

Finally, I will exemplarily show the application of MC-ICPMS Th/U-dating to stalagmites, which are one of the best suited materials for U-series dating, and discuss the implications in terms of past climate variability.