See more from this Division: Topical Sessions
See more from this Session: Terrestrial Response to Climate Variability during the Medieval Warm Period: Lakes, Tree-Rings, and Human Adaptation
Abstract:
We are conducting a regional evaluation of terrestrial-derived biomarkers and their isotopic compositions, which should be sensitive to changes in evaporation and transpiration, to assess the severity and spatial extent of hydrologic changes during the Classic Maya period. Our preliminary data, derived from hydrogen isotope values (dD) of C29, C31 and C33 terrestrial-derived n-alkanes in Lake Chichancanab sediments, show centennial-scale variability in evapo-transpiration over the past 3000 years, including during the Terminal Classic period. This record, however, does not reveal significant dD increase above the mean value during the Terminal Classic, implying that regional aridity during the collapse was not more severe than at other times. This finding is in conflict with records of shell-carbonate d18O and sulfate deposition within the same core, which were interpreted as indicating increased evaporation/precipitation (E/P) during this period. Inconsistency between these two proxy records suggests that: 1) organic biomarkers fail to record aridity reliably, or 2) one or both sets of climate proxies have been misinterpreted. We will expand our analysis to include other biomarkers at this site and other localities, and we will ground-truth the use of hydrogen isotopes of lipids as recorders of regional E/P.
See more from this Division: Topical Sessions
See more from this Session: Terrestrial Response to Climate Variability during the Medieval Warm Period: Lakes, Tree-Rings, and Human Adaptation