C, Sr and Pb isotopic chemostratigraphy in precambrian carbonate sequences in the eastern transversal domain of the Borborema province, Northeastern Brazil - Santos, V. H.; Ferreira, Valderez; Sial, Alcides Nobrega; Babinski, Marly; Pimentel, Marcio Martins (South American Symposium on Isotope Geology, 2001)