Raman non-destructive analysis of visible tephra layers in ice cores

Ice cores are exceptional archives of past climate variability, preserving forcing factors and proxies of the climate system’s response. Volcanic eruptions, when recorded as englacial tephra layers, provide insights into explosive volcanism, volcano–climate interactions, and enable long-range synchronization of paleoclimate records, provided the eruptive source is identified. Source attribution of far-travelled tephras requires geochemical characterisation of volcanic glass and comparison with known reference compositions. This task is complicated by the broad range of potential sources and the geochemical similarity of eruptive products. In this context, volcanic minerals, though less commonly used than glass, offer a valuable complementary tool for fingerprinting their source rocks.

More broadly, most analytical protocols rely on melting ice cores, compromising the preservation and future reuse of this important natural archive. As climate change poses increasing threat to global ice reserves, developing an innovative approach is critically needed.

Here, we present a novel, non-destructive Raman spectroscopy–based approach to analyse the mineralogy of visible tephra layers in ice cores. A tephra from Campbell Glacier, Antarctica (74°16′59″ S 164°10′52″ E), has been used to demonstrate advantages and pitfalls of this approach. The observed mineral assemblage is consistent with a strongly alkaline source and with its geochemical signature. This mineralogical dataset enables tephrochronological reconstructions and improves the precision and reliability of established analytical approaches for volcanic source fingerprinting.