HIGH-RESOLUTION STALAGMITE RECORD EXAMINING LOCAL HYDROCLIMATE VARIABILITY FROM A SHALLOW CAVE IN SEMI-ARID NEW MEXICO

Recent speleothem studies have established high-resolution (annual to sub-annual temporal scale) stalagmite records that extend over the over the Common Era and capture extreme events (e.g. cyclones and flood events) in climate change hotspots. Southwestern United States (especially New Mexico) currently lacks a stalagmite based detailed understanding for its recent climate history. Here we present a high-resolution multi-proxy study from southeastern semi-arid New Mexico, combining trace element geochemistry, fluorescent imaging, and radiometric dating of three stalagmites and concomitant cave monitoring from a shallow cave. Following numerous statistical analyses and tests (Principal Component, Continuous Wavelet, Peak Counting) on a suite of trace elements (major alkali-earth and transition metals) we develop a high-resolution age model that spans 1930 to 2009 C.E. Our age model is independently constrained using radiocarbon, U-Series dates and the known 1931/32 C.E winter cave ceiling collapse that altered the cave system. We provide results from one year of cave monitoring including analyses of drip water alkali-earth metals, drip rates and calcite substrate growth at three different drip flow paths (conduit, diffuse, intermediate). Cave monitoring results suggest that growth rate is the main driver of Sr/Ca drip water variability independent of drip flow path regime. Mg/Ca drip water is sensitive to temperature variability for an intermediate drip flow path. The speleothem record is calibrated against local instrumental records (Palmer Drought Severity Index) in New Mexico. Our results indicate that during drought years, winter based infiltration events, expressed as sudden increases in transition metals, are recorded in the stalagmite but summer events fail to be recorded. In addition, we observe summer and winter infiltration events captured during non-drought years by the stalagmite record. Indeed, our results are consistent with climatological semi-arid region studies that show the importance of effective winter infiltration during drought years.