In situ LA-ICPMS U-Pb zircon dating of the host rocks of the Sossego and Bacaba iron oxide-copper-gold deposits, Carajas Mineral Province, Brazil

The world-class Sossego and the Bacaba iron oxide-copper-gold deposits are located in the southern margin of the Carajas Domain, Carajas Mineral Province, along a regional WNW-ESE-striking shear zone. In the Sossego deposit, U-Pb LA-ICPMS zircon data for the host Granophyric Granite and the Sequeirinho Granite returned dates of 2740 +/- 26 Ma and 3010 +/- 21 Ma, respectively. In the Bacaba deposit, zircons from the Bacaba Tonalite and the Serra Dourada Granite yielded dates of 3001 +/- 4 Ma and 2860 +/- 22 Ma, respectively. These dates are interpreted as the igneous crystallization age of the host rocks and could represent one of the oldest magmatic events recognized in the Carajas Domain. The 3.0 Ga old Sequeirinho Granite and Bacaba Tonalite and the 2.86 Ga old Serra Dourada Granite are interpreted to largely predate the genesis of the Sossego and Bacaba deposits. A genetic link with these intrusive rocks is unlikely because the Sossego and Bacaba deposits might represent different portions of the same hydrothermal system, which is hosted by the younger 2.74 Ga Granophyric granite (Sossego deposit). In this context, these deposits could be mainly controlled by important crustal discontinuities, such as regional shear zones, rather than be associated with a particular rock type.