PALEOHYDROLOGIC RECONSTRUCTION OF YAX CHEN CAVE (YUCATAN PENINSULA, MEXICO) IN RESPONSE TO HOLOCENE CLIMATE CHANGE

Abstract

Four sediment cores and ten sediment trap samples were collected from Yax Chen cave, part of the Ox Bel Ha cave system on the Yucatan Peninsula in Mexico, for microfossil and micro-XRF geochemical analysis. In cores, Cl ̄trends (measuring salinity changes in meteoric water mass) show a direct relationship with microfossil (specifically the foraminifer Elphidium spp.) and weathering proxies (K, Ti, and Fe) used for measuring wet/dry conditions. Micro-XRF measurements of Cl ̄are derived from pore water in the cores, allowing for a more accurate observation of change in the cave system. Conversely, weathering proxies are measured from transported sediments. All four cores show a general decrease in groundwater salinity up core. Two of the cores, which were collected above the present halocline (~11m), show salinity changes in the meteoric water mass. One core was collected at the halocline and measures its movement in response to precipitation and Holocene sea-level rise. These findings are in agreement with other studies from the Yucatan coast (e.g. cenotes Aktun Ha and Sac Actum) as well as other paleoclimate records in the region. Additionally, these findings correlate with archaeological evidence, revealing several droughts that occurred throughout late Pre-Classic to late Classical Maya. High resolution analysis of Cl ̄offers new insights on how coastal aquifers respond to climate change and may have implications for regional archaeology. The use of micro-XRF geochemical analysis is an effective tool which can be used to understand the spatial and temporal complexities of Yucatan coastal aquifers.