Lead isotope variability in speleothems-A promising new proxy for hydrological change? First results from a stalagmite from western Germany

We studied an aragonitic section of ca. 6 cm length of stalagmite HBSH-1 from the Huttenblaserschachthohle, western Germany. Th-230/U-dating revealed that this section grew between similar to 210 and similar to 190 ka, with a relatively uniform growth rate of 3.1 mu m a(-1). For the first time, we determined Pb isotope ratios (Pb-207/Pb-206 and Pb-208/Pb-206) in a stalagmite by laser ablation (LA)-ICP-MS. In addition, we analyzed various trace element (Mg, Al, Si, P, Mn, Sr, Pb and Th) concentrations. The results indicate that Pb in HBSH-1 originated from two external sources: (i) the regional galena (PbS) mineralization with high Pb content as well as isotope ratios, and (ii) the carbonate fraction in the host rock with low Pb content as well as isotope ratios. Except for Sr, all trace elements show similar variations, probably driven by the amount of infiltration into the cave system. This is probably the result of the similar transport and incorporation mechanisms of these elements as colloids and/or particles. The Pb isotope ratios also show a strong correlation with trace element variability strongly suggesting that the Pb isotope variability in HBSH-1 has the potential to be used as a promising new proxy for hydrological change. Based on the observed variability, we identify two phases (from similar to 204.9 to similar to 201.5 and from similar to 198.4 to similar to 195.9 ka) with enhanced water infiltration in the cave region. Between similar to 210.0 and similar to 204.9, similar to 201.5 and similar to 198.4 as well as similar to 195.9 and similar to 190.0 ka less infiltration occurred. (C) 2015 Elsevier B.V. All rights reserved