A 2600 year BP Lacustrine Record of Seismic Events and Hydroclimate Variability from Lake Chichój, Central Guatemala based on Sediment Core Analysis and Carbonate Isotopes

Sediment cores collected in 2017/2018 from Lake Chichój, located in the central Highlands of Guatemala, were analyzed to reconstruct the basin history and compile a high-resolution hydroclimatic record over the last ~2600 years BP. Fine-grained endogenic carbonates sampled at 2 mm resolution (n=957) were analyzed for carbonate isotopes (δ¹⁸O and δ¹³C), allowing for stratigraphic correlation between cores, as well as a proxy record of regional paleoclimate. Since Lake Chichój is located within 2 km of the Montagua-Polochic fault zone, the sediment likely contains a history of seismic events that could potentially overprint the paleoclimate signal and thus must be identified in order to isolate the hydroclimate signal. Basin analysis techniques were applied through the use of Scanning Electron Microscopy, X-Ray Diffraction, X-Ray Fluorescence, Magnetic Susceptibility and Loss-on-Ignition methods. Large excursions in the carbonate isotopic signature of the lake from pulses of detrital limestone, as well as fluxes of quartz rich sediments from the Los Chocoyos pumaceous ash aided in our assessment of past paleo-seismic events. Age control is based on ²¹⁰Pb and 20 discrete ¹⁴C dates, with chronological uncertainty estimated using Bayesian methods . These data will yield information on precipitation variability and can be used to improve water management in a region containing ~94 thousand people. Additionally, this study will improve the quantitative assessment of hydroclimate throughout the Holocene in Central Guatemala, allowing for advances in modeling and drought forecasting.