Tellurium and selenium in Mesoproterozoic red beds

Samples of red bed sediments in several Mesoproterozoic successions contain enrichments of tellurium (Te), including discrete telluride minerals. The tellurides were neoformed during redox-controlled diagenesis, rather than representing mechanical concentrations of heavy minerals. Tellurium is enriched relative to selenium, which may reflect erosion of Archean and Palaeoproterozoic rocks with high Te contents. High continentality during the Mesoproterozoic would have limited the delivery of Te and other trace elements to the oceans, so accumulated Te on the continents.