Thallium isotopes in Iceland and Azores lavas — Implications for the role of altered crust and mantle geochemistry (original) (raw)

Mantle plumes are commonly perceived to have both a chemical and dynamic link with the subduction of ocean crust into the mantle. In principle, this should lead to the observation of chemical and isotopic signatures that are characteristic of ocean crust and marine sediments in ocean island basalts. This study investigates the thallium (Tl) isotope systematics of lavas from Iceland and the Azores archipelago, in order to determine if their compositions were affected by admixing of ferromanganese sediments or upper ocean crust altered at low temperature. Such materials are known to display strongly fractionated Tl isotope signatures relative to the ambient upper mantle.