Comparison of high-resolution SIMS profiles with maximum resolution IRMS stable isotope data

High-resolution speleothem paleoclimate records with annual to seasonal resolution are helpful for detailed analysis of climatic changes with limited duration (e.g., volcanic climate impacts), but also for longer-duration events (e.g., at 8.2 ka or 4.2 ka). A high resolution paleoclimate data set is also mandatory for meaningful comparison with archaeological or historical records. Low stalagmite growth rates could impede the acquisition of high-resolution isotope data with the classical micro-milling approach and isotope ratio mass spectrometry (IRMS) analysis. We therefore compared secondary ionization mass spectrometry (SIMS) stable isotope measurements at 7-15 µm resolution with the lower-resolution micro-milling results at 90 µm steps. For the investigated stalagmite from Kleine Teufelshöhle (Frankonia, Germany) the SIMS resolution corresponds to annual resolution, whereas IRMS only reaches a 4-13 year resolution. Albeit a constant offset, SIMS and IRMS δ18O data match very well (r = 0.61, p < 0.001, n = 84). This significant correspondence suggests that SIMS stable isotope analysis could be a promising alternative for high-resolution carbonate studies. An adjacent second δ18O SIMS profile reproduced high-resolution features (r=0.59, p < 0.001, n = 982) and allows a detailed assessment of paleoclimate variability on an annual scale and a comparison with independent climate records, e.g., weather information from historical documents or tree rings. Stalagmite δ18O trends closely follow the low-frequency fluctuations of a regional tree-ring record (Land et al., 2019), additionally constraining the stalagmite chronology. The different climate sensitivities of both records enable a more robust and detailed discussion of paleoclimatic variations.