Using stable oxygen isotope dual‐inlet isotope‐ratio mass spectrometry to elucidate uranium transport and mixed ²³⁰Th/U calcite formation ages at the seminal Devils Hole, Nevada, natural laboratory

The continuously submerged Devils Hole δ¹⁸O chronology is not explained by orbital forcing. Rather, this chronology represents a regional climate record in the southern Great Basin of sea-surface-temperature (SST) variations off California, variations that preceded the last and penultimate deglaciations by 5000 to approximately 10 000 years. Temporal discrepancies between the continuously submerged Devils Hole chronology and other regional δ¹⁸O records (e.g., the Leviathan chronology) can be explained by unrecognized cryptic, pernicious uranium mobility, leading to model estimations that may be thousands of years younger than actual ages. Consequently, paleo-moisture availability, water-table, and groundwater recharge models based on these mixed uranium-series ages are too young by as much as 12 000 years. The potential for post-formation uranium addition in subaerial cores and speleothems underscores the need for caution in uranium-series dating, highlighting δ¹⁸O time-series comparisons as a method for identifying mixed ages.