Hydrological and climatological controls on radiocarbon concentrations in a tropical stalagmite

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Lechleitner, Franziska, Baldini, James, Breitenbach, Sebastian, Fohlmeister, Jens, McIntyre, Cameron, Goswami, Bedartha, Jamieson, Robert, van der Voort, Tessa, Prufer, Keith, Marwan, Norbert, Culleton, Brendan, Kennett, Douglas, Asmerom, Yemane, Polyak, Victor, Eglinton, Timothy
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Zenodo 2016
• Subjects: North Atlantic
• Online Access: https://doi.org/10.1016/j.gca.2016.08.039

Precisely-dated stalagmites are increasingly important archives for the reconstruction of terrestrial paleoclimate at veryhigh temporal resolution. In-depth understanding of local conditions at the cave site and of the processes driving stalagmitedeposition is of paramount importance for interpreting proxy signals incorporated in stalagmite carbonate. Here we present asub-decadally resolved dead carbon fraction (DCF) record for a stalagmite from Yok Balum Cave (southern Belize). Therecord is coupled to parallel stable carbon isotope (d13C) and U/Ca measurements, as well as radiocarbon (14C) measurementsfrom soils overlying the cave system. Using a karst carbon cycle model we disentangle the importance of soil and karst processeson stalagmite DCF incorporation, revealing a dominant host rock dissolution control on total DCF. Covariationbetween DCF, d13C, and U/Ca indicates that karst processes are a common driver of all three parameters, suggesting possibleuse of d13C and trace element ratios to independently quantify DCF variability. A statistically significant multi-decadal lag ofvariable length exists between DCF and reconstructed solar activity, suggesting that solar activity influenced regional precipitationin Mesoamerica over the past 1500 years, but that the relationship was non-static. Although the precise nature of theobserved lag is unclear, solar-induced changes in North Atlantic oceanic and atmospheric dynamics may play a role.