Crystallization processes (nucleation and growth) have a role in the “kinetic” incorporation of isotopes and trace elements in calcium carbonate crystals. Non-equilibrium incorporation of chemical species can be explained by ultra-high resolution investigation and allows advances in our capability of interpretation of climate proxies to be made. Therefore, if we strive towards an accurate interpretation of speleothem proxy data, we should start from petrographic observations to check for the presence of non-equilibrium fabrics and possible diagenetic modifications.

This petrography workshop is divided into three sections. In the first part the participants will learn how to recognise the most common types of speleothem fabrics and hiatuses, as well as to understand their characteristics and the known climate and environmental parameters underpinning their development. They will also learn about the most technically advanced techniques for nano-scale investigation, what information they provide and where to access them. The second part will focus on the construction of the petrographic log. There will be an open discussion about different approaches utilised to convert petrographic observations in numerical values in order to compare petrography with speleothem geochemistry. High resolution scanning of polished speleothem slabs will be introduced as one of the best tools to construct fast petrographic logs from very long stalagmite samples or flowstones. In the third part, the participants will observe under a petrographic microscope thin sections of the most common speleothem fabric. We also encourage participants to bring their own thin sections and/or polished speleothem slabs, or other types of continental carbonates.