Investigating Mexican Paleoclimate with Precisely Dated Speleothems

Gabriela Serrato Marks, Ph.D., 2020
David McGee, Advisor

Speleothems are valuable archives of past climate change due to their suitability for U-series dating and high-resolution proxy analysis. These records can provide insights into water availability and controls on hydrology prior to the instrumental record. In this thesis, I present three records from newly-analyzed Mexican stalagmites using stable isotope (oxygen and carbon) and trace element to calcium (Mg/Ca and Sr/Ca) ratios as proxies for changing hydroclimate. Chapter 2 presents a mid-Holocene record of high rainfall and limited precipitation variability in the Yucatan Peninsula. Chapters 3 and 4 present novel climate records from northeastern Mexico, an understudied region of North America. First, I examine a speleothem from the first millennium of the Common Era, which showed a precipitation dipole between northern and southern Mexico. Chapter 4 highlights, for the first time at decadal resolution, the northeast Mexican response to the 8.2 ka event and the Younger Dryas. These chapters show that northeast Mexico is vulnerable to droughts under multiple climate mean states, and is subject to drying as Atlantic Meridional Overturning Circulation weakens in the future. The climate records detailed in this thesis improve our understanding of controls on Mexican hydroclimate and can serve as benchmarks for climate models.