Sensitive, spatially resolved U-Th dating approach using LA-ICPMS

ended

The U-Th dating system is broadly exploited to determine the timing and process of Earth’s geological, environmental, and biotic evolution for materials as young as few years to over the last 800 thousand years (kyrs). Contemporary solution phase U-Th dating protocol using thermal ionization mass spectrometry (TIMS) or multi collector-inductively coupled plasma mass spectrometric (MC-ICPMS) can provide high precision dates with errors of ±1-4‰ (2σ) on ages from 5 to 100s kyr; however, it still restricted by the discrete milli-domain (mm) sampling strategy and the time-consuming chemical preparation procedure. Laser ablation-inductively coupled plasma mass spectrometric (LA-ICPMS) could serve the strengths of rapid, in-situ, and high lateral scanning to U-Th dating. Until nowadays laser U-Th dating approach is sparsely reported due to its reduced sensitivity and precision. Here the experience researcher (ER) designs and employs methods by means of a solution-based correction strategy with a jet-interface setup. This new configuration could essentially reduce the uncertainties and enhance the sensitivity significantly. Based on the ER's previous training, he has firm knowledge and skills in conducting high precision carbonate U-Th dating protocol using MC-ICPMS (Shen, Wu et al., Geochim. Cosmochim. Acta, 2012), and the anlaysis of rare earth elements using LA-ICPMS (Wu et al., Anal. Chim. Acta, 2018). The expected outputs of this SPATULA project are: 1) improve the resolution of age assignments from the milli-domain (mm) to micro-domain (μm). 2) provide in situ analysis using LA-ICPMS to overcome time-consuming element separation processes requiring hazardous chemicals. 3) apply this μm-domain laser U-Th dating approach to tephra-containing stalagmite samples, to reconstruct high resolution volcaican eruption profiles. This sensitive, spatially U-Th dating approach, has the potential to be applied to diverse fields such as oceanograpgy, geomagnetics, and archaeology.