Late Quaternary hydroclimate variability in the Colombian Andes and the potential for deep sediment core recovery at Lago de Tota revealed through CHIRP and airgun-sourced seismic reflection data

Abstract

A geophysical investigation of lacustrine stratigraphy at Lago de Tota (Tota), Boyaca, Colombia provides evidence for significant lake level fluctuations during the late Quaternary from ~60 ka to the present. CHIRP data collected in 2015 from this large, high-elevation lake in the Eastern Cordillera of the Northern Hemisphere (NH) Colombian Andes reveal a series of off-lap and on-lap sequences in the upper ~20 m of the lake’s sediment column that indicate large amplitude changes in lake level. These data, temporally constrained by 14C-dated sediment cores and extrapolated Holocene sedimentation rates, suggest that lake levels at Tota were lower than present during Marine Isotope Stage (MIS) 4 between 60 and 57 ka, relatively high during MIS 3 between 57 and 29 ka, fell to their lowest levels during MIS 2 between 29 and 14 ka, and gradually rose to the modern high-stand through a series of transgressions during MIS 1 and the Holocene from ~14 ka to the present. These fluctuations are broadly consistent with trends observed in other lake level reconstructions from the Northern (in phase) and Southern (out of phase) Hemisphere Andes, possibly supporting the idea that millennial-to-orbital-scale South American hydroclimate variability is linked to shifts in the mean latitude of the Intertropical Convergence Zone (ITCZ) due to the influence of insolation- and ocean circulation-driven hemispheric temperature gradients during glacial/stadial and interglacial/interstadial events. These results, as well as the presence of a thick (>300 m) sedimentary archive, indicate that Tota has significant potential to produce high-resolution, quantitative, paleo- hydroclimate data spanning much of the last 1 million years. Because geophysical surveys and long paleoclimate records from NH South America are exceedingly rare, these data provide critical insight into regional hydroclimate trends through the Late Quaternary.