Chemical element imaging for speleothem geochemistry: Application to a uranium-bearing corallite with aragonite diagenesis to opal (Eastern Siberia, Russia)

► Autoradiography and micro-XRF were used to study the geochemistry of a speleothem. ► Exceptional high uranium contents, from 3 to 1300 μg ∙ g− 1 were found in the sample. ► We use calcite replacement by uraniferous opal to date specific events like volcanism. ► We show that speleothem diagenesis can impact validity of radiometric dating. ► Chemical imaging analysis easily provides original information about diagenesis.