Speleothem-Based Hydroclimate Reconstruction of Northeastern Mexico Across the Last Deglaciation

Abstract

As anthropogenic global warming intensifies, climate models predict more frequent drought conditions across Northeastern Mexico, but regional paleoclimate data is necessary to inform the spatial extent and severity of these droughts. In this thesis, we present a centennial-scale resolution record of Northeastern Mexico hydroclimate spanning 21.77 to 11.56 ka using a speleothem from Rioverde, San Luis Potosí, Mexico. We use trace element ratio data to reconstruct local water balance (P - ET) and compare our results to neighboring proxies and climate models to investigate regional coherency and climate forcings. Our record captures wet conditions during the Last Glacial Maximum, dry conditions during Heinrich Stadial 1, and wet conditions during the Bolling-Allerod Warming, with implications for defining glacial climate and assessing the Mesoamerican North-South precipitation dipole on millennial to orbital timescales. Our results also demonstrate a dynamic control on precipitation via changes in the Atlantic-Pacific SST gradient. Furthermore, our results help fill a crucial gap in our knowledge of the climatic background of the First Peopling of the Americas and offer a potential route for the Peopling of Mexico between 15.5 and 13 ka. Ultimately, this work provides a precisely dated and high-resolution record in an understudied region to better predict future climate and reconstruct human history.S.B