U-PB DATING OF DEFORMED MAFIC DYKE AND HOST GNEISS: IMPLICATIONS FOR UNDERSTANDING REWORKING PROCESSES ON THE WESTERN MARGIN OF THE ARCHAEAN UAUÁ BLOCK, NE SÃO FRANCISCO CRATON, BRAZIL

ELSON PAIVA OLIVEIRA, ZORANO SÉRGIO SOUZA, LUIZ CESAR CORRÊA GOMES

Resumo


U-Pb ages of deformed mafic dyke and host migmatitic grey gneiss from the transition zone between the Archaean Uauá Block and the Caldeirão Belt are presented. Titanites from the metamorphic dyke’s margin and zircons from the gneiss were dated at 2,039 ± 2 Ma and 2,956 ± 39 Ma, respectively. The Sm-Nd data (TDM=2,965 Ma and εNd(t)=1.69) on the gneiss, coupled with the U-Pb data on both dyke and gneiss, suggest that an Archaean granodioritic batholith, probably originated at an Andean-type continental margin, was intruded by mafic dykes, and subsequently was reworked during the Palaeoproterozoic collisional event associated with the development of the Salvador-Curaçá Orogen.

Palavras-chave


U-Pb geochronology; Deformation; Crustal evolution.

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