Transamazonian tectonism and Au-Pd mineralization at the Cauê Mine, Itabira District, Brazil: Pb isotopic evidence

Pb isotopic results are reported for mineral separates from iron formations that host Pd-Au mineralization at the Cauê Mine, in the Itabira District of the Southern São Francisco Craton, as well as for an amphibolite that has been tectonically imbricated with the iron formations during the earliest D1 tectonic event in this area. Pb isotopic results were obtained for hornblende and ilmenite that were rotated within the regional S1 foliation of an amphibolite. These minerals yielded a metamorphic age of 2.66 ± 0.27 Ga and a time-integrated μ1 value of 8.35. This shows, for the first time, the involvement of late Archean to Paleoproterozoic basement rocks in the tectonic history of the Itabira District; this unit is tentatively correlated with the Archean Rio das Velhas Supergroup in the Quadrilátero Ferrífero. topic results were also obtained for quartz, gold and specular hematite that were formed during the transformation of the iron formations into itabirite and jacutinga which occurred during the D1 event. These minerals, which are stretched within the S1 foliation plane, yielded an age 1.83 ± 0.10 Ga which corresponds to the Tranzamazonian Orogenesis in the southern part of the São Francisco Craton. Other Pd-bearing gold deposits hosted in Minas Supergroup iron-formations of the southern São Francisco Craton have many similarities with the Cauê mine, suggesting that Pd-Au mineralization may have been a widespread process associated with the tectonic transport of the Minas sequence during the Transamazonian orogenesis.