Abstract
Oxygen isotopes (δ(18)O) are the most commonly utilized speleothem proxy and have provided many foundational records of paleoclimate. Thus, understanding processes affecting speleothem δ(18)O is crucial. Yet, prior calcite precipitation (PCP), a process driven by local hydrology, is a widely ignored control of speleothem δ(18)O. Here we investigate the effects of PCP on a stalagmite δ(18)O record from central Vietnam, spanning 45 - 4 ka. We employ a geochemical model that utilizes speleothem Mg/Ca and cave monitoring data to correct the δ(18)O record for PCP effects. The resulting record exhibits improved agreement with regional speleothem δ(18)O records and climate model simulations, suggesting that the corrected record more accurately reflects precipitation δ(18)O (δ(18)O(p)). Without considering PCP, our interpretations of the δ(18)O record would have been misleading. To avoid misinterpretations of speleothem δ(18)O, our results emphasize the necessity of considering PCP as a significant driver of speleothem δ(18)O.