THE PB PB AGE OF THE MINAS SUPERGROUP CARBONATE ROCKS, QUADRILATERO FERRIFERO, BRAZIL/

Pb/Pb isochron ages determined on carbonate rocks from the Minas Super group, Quadrilatero Ferrifero (QF), show that the deposition of the Ga ndarela Formation, the intermediate unit of the Minas Supergroup, took place at 2420 +/- 19 Ma. The entire sedimentary sequence and underlyi ng basement rocks have been deformed at a regional scale, and data fro m greenschist facies carbonate rocks from the Piracicaba Group indicat e that the Pb isotopes were reset at about 2100 Ma. This age is in agr eement with whole-rock Rb/Sr and U/Pb titanite ages determined by many authors for metamorphism of the surrounding Archean granite-gneiss te rrane.