Applied isotope geochemistry

In addition to studying Earth’s differentiation, evolution of the mantle and crust, and cycling of elements, the group also applies isotope geochemical tools to solve questions in metamorphic petrology, climate science, archeology, and forensic science. Here we show several examples of these collaborative projects:

Archeometric and forensic use of Sr and Pb isotopic compositions.

The radiogenic 87Sr and 206,207,208Pb isotopes are strongly variable among different geological formations, as a result both of the rocks' age and their enrichment in radioactive parent isotopes. The Sr and/or Pb isotopic compositions can be exploited to identify potential provenance areas both of archeological artefacts and of human bone remains. Examples include the Pb isotopic investigation of the sources of the earliest metal objects from the Neolithic, the identification of prehistoric ore mining in local micro-centers as opposed to large centralized long-distance distribution hubs, the extension of Mediterranean maritime trade in the Iron Age, the minting rights of medieval coins, and the provenance of pigments in medieval artwork. Applications to forensics are the coupled Sr-Pb analyses of teeth, which allowed the identification of a Swiss warlord of the Renaissance and the dietary homogeneity of a population in an Iron Age graveyard.

Systematics of mineral ages and transport of radiogenic isotopes in silicate minerals.

The observation of microtexturally-controlled regular chemical variations in metamorphic minerals is a prerequisite to explore the connection between petrology and geochronology. Unravelling the relative rates of retrograde reactions, dissolution/reprecipitation, and diffusion is the key to correctly understand the geochronology of metamorphic rocks.

234U-230Th disequilibrium dating of carbonate formation.

Many carbonates (speleothems, coral skeletons, phreatic overgrowths) are proxies of past climatic conditions (both humidity and temperature) and/or of past sea level changes. Dating such climatic proxies provides constraints that aid the validation of global climatic models.