Robert R. Seal, II Lauren T Reid James A Jordan Adam C. Mumford Tyler B. Coplen 2024 <p>Rationale</p><p><span>Vein calcite in Devils Hole has been precipitating continuously in oxygen-isotope equilibrium at a constant temperature for over 500 000&nbsp;years, providing an unmatched&nbsp;</span><i>δ</i>¹⁸<span>O paleoclimate time series. A substantial issue is that coeval calcite (based on matching&nbsp;</span><i>δ</i>¹⁸<span>O values) has uranium-series ages differing by 12 000&nbsp;years.</span></p><p>Methods</p><p><span>An unparalleled high-accuracy&nbsp;</span><i>δ</i>¹⁸<span>O chronology series from continuously submerged calcite was used to correct the published uranium-series ages of non-continuously formed calcite in two cores, cyclically exposed by water-table decline during glacial–interglacial transitions. This method relies on the premise that the&nbsp;</span><i>δ</i>¹⁸<span>O values of coevally precipitated calcite are identical, allowing matching calcite&nbsp;</span><i>δ</i>¹⁸<span>O values to establish formation ages.</span> </p><p>Results</p><p><span>Exposed calcite can have apparent ages that are 12 000&nbsp;years too young due to unrecognized uranium mobility and resulting mixed ages identified in over 50 mixed uranium-series ages from previous studies. Secondary uranium in fluids, sourced from the formation or dissolution of porous carbonate deposits (folia) with high uranium-238 (</span>²³⁸<span>U) concentrations, has migrated up to 10&nbsp;mm into vein calcite.</span></p><p>Conclusions </p><p><span>The continuously submerged Devils Hole&nbsp;</span><i>δ</i>¹⁸<span>O 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&nbsp;years. Temporal discrepancies between the continuously submerged Devils Hole chronology and other regional&nbsp;</span><i>δ</i>¹⁸<span>O 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&nbsp;years. The potential for post-formation uranium addition in subaerial cores and speleothems underscores the need for caution in uranium-series dating, highlighting&nbsp;</span><i>δ</i>¹⁸<span>O time-series comparisons as a method for identifying mixed ages.</span></p> application/pdf 10.1002/rcm.9926 en Wiley 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 article