T177 Karst Sedimentary, Paleoclimate, and Historical Records (Posters)

Tuesday, 17 October 2023
8:00 AM - 5:30 PM
Hall B

CALIBRATION OF STALAGMITE δ18O FOR PALEOCLIMATIC INTERPRETATIONS IN CUEVA ENSUEÑO, HATILLO, PUERTO RICO

Paper number: T177-4
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Stalagmites are valuable climatic geological archives. Their stable oxygen isotope composition, denoted δ18Occ, are important climatic indications because they closely reflect the isotopic composition of the drip water, δ18Ow, from which they precipitate. The oxygen isotopic fractionation between carbonate and the drip water, 18αcc/w, is temperature dependent, as has been shown in previous cave compilation studies. Understanding this thermodynamic equilibrium is critical in cave studies prior to developing paleoclimate records from stalagmites, specifically that various factors inside and outside the caves may alter δ18Ow and eventually δ18Occ. Here, we calculated 18αcc/w within Ensueño Cave, located in the northern karst region of Puerto Rico as a preliminary approach to calibrate the stable isotope proxy we plan to develop from its stalagmites. To achieve this, we measured δ18Occ, δ18Ow, and the temperature of the drip water. These measurements were done at 10 different stations inside the cave. Overall, 18αcc/w fits within the global cave calibration curves, with small variations. To understand possible factors leading to these variations, various physiochemical properties of the drip water were examined, including pH, electrical conductivity, total dissolved solids, drip rate, and saturation index (SIcalcite). For a more comprehensive study, the pCO2 and relative humidity of the cave atmosphere at each station were investigated. Preliminary Principal Component Analyses of these variables suggest some relationship between the drip water pH and 18αcc/w . More study will be done to investigate potential factors driving changes in 18αcc/w. This study can be of importance while improving proxy calibration using stalagmites.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-392922

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