T62 Karst Processes and Speleology (Posters)

Sunday, 9 October 2022
2:00 PM - 6:00 PM
Exhibit Hall F

LATE HOLOCENE HYDROCLIMATE CHANGES RECORDED IN ẟ18O OF A STALAGMITE FROM CUEVA DE LA FABRICA, COLOMBIA

Paper number: T62-12
Program: Technical Sessions
Time: 2:00 PM – 6:00 PM

Authors

Abstract

Speleothems, calcium carbonate (CaCO3) cave deposits, are an important archive used to reconstruct past terrestrial hydroclimate variability. Cave drip water chemistry (i.e., trace elements and stable isotopes) influences speleothem growth layers as it precipitates, which makes speleothems great archives for changes in the hydroclimate. Speleothems that grew before the availability of instrumental data provide an understanding of changes in rainfall by recording the response of past climate to changes in internal and external climate forcings.

In this study, we analyze the stable isotope variability of a speleothem, C2A-1, that grew between 3,206 ± 63 (2σ) and 3,750 ± 110 yrs B.P in Cueva De La Fabríca, Colombia. In Colombia, there are no published stable isotope measurements of speleothems, although insights from such analyses would benefit the interpretations of several regional isotope-based paleoclimate records. In this region, δ18O values are sensitive to changes in rainfall. The cave lies near the boundary of wet and dry El Niño and may provide crucial insight into El Niño trends during Pre-Muisca cultures. We micro-milled C2A-1 at a 500 mm resolution to yield 283 samples. δ18O values fall between -7.07 and -8.33 ‰ (V-PDB) and δ13C values are between 1.37 and 3.40 ‰ (V-PDB). The carbon isotope values are high compared to existing speleothem isotope data from surrounding countries, which might suggest a C4 vegetation. Both isotope proxies indicate systematic changes in rainfall and vegetation. Our data suggests sub-decadal hydroclimate variability (~1.5 ‰ in δ18O) over a 600-year period. We compare our new terrestrial paleoclimate record against coral records from the central and eastern Pacific to discern the similarities and differences in the hydroclimate response during the late Holocene. In combination with observations of modern hydroclimate, trends in stable isotope variation could provide insight into how hydroclimate in Colombia and the eastern tropical Pacific may look in the future.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-381564

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