121 Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology

We welcome submissions on the biogeochemistry, astrobiology, and historical records in of caves and karst features.

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 211

Mg and Sr: Excellent predictors for calcite and aragonite presence in stalagmites

Paper number: 121-13
Program: Technical Sessions
Time: 4:50 PM – 5:05 PM

Authors

Abstract

Stalagmites are excellent paleoclimate archives. Detailed documentation of their mineralogy and petrography is fundamental for a robust interpretation of paleoclimate time series. Changes in temperature, changes in rainfall, and changes in cave environments, such as the presence or the absence of biological mediators, directly influence the mineralogical composition and the petrographic variations of stalagmites. A few studies have shown that mineral variations in stalagmites are closely tied to changes in elemental composition. Specifically, the changes in magnesium (Mg) and strontium (Sr) concentration can be used to predict carbonate polymorph variations. Using this prior knowledge, we hypothesize that Mg is a good indicator for the presence of calcite and Sr is a good indicator for the presence of aragonite. To test this hypothesis, we combined three methods. First, we used X-ray Diffraction (XRD) discrete analyses to quantify phase percentages. Second, we used Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) line scans to develop an element depth series. Third, we used an Atlas X micro XRF Spectrometer to map elements. The elemental analyses using LA-ICP-MS and microXRF were used to cross-check the phase quantification using the traditional XRD method. Our findings demonstrate that Mg and Sr are indeed an excellent predictor for the presence of calcite and aragonite, respectively, in stalagmites. More specifically, we found that Mg is high in calcite but low in aragonite, and Sr is high in aragonite but low in calcite. The combination of Sr and Mg can be used to develop a useful depth series index to accurately quantify mineral variations in stalagmites, which is useful in refining paleoclimate datasets.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414240

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