Phosphorus-uranium occurrences of Serrotes Baixos, state of Ceara, Brazil

The Serrotes Baixos phosphorus-uranium showing is located 28 Km south of Santa Quiteria and it is geologically related to the Complexo Tamboril/Santa Quiteria rocks (Transamazonico Cycle) which are represented by a migmatitic-granitic basement and relicts of gneisses and ectinict lithologies (calc-silicated rocks, marbles, etc.). Granodiorite granites and gabbros were formed by plutonic activity occurring in the area. Four folding phases were identified: the first two systems are isoclinal recumbent folds and the last two are subvertical open folds. The faults are mainly transcurrent in nature and were reactivated as gravity faults around the end of the Brasiliano Cycle. The phosphorus-uranium mineralization occurs, at the surface, related to episyenites and, at depth, associated to the brecciated calc-silicated rocks. The mineralization (collophane/apatite with uranium) also occurs as stockworks in marbles and as disseminations in gneisses. The Serrotes Baixos area mineralization appears to be more phosphatic and less uraniferous when compared to the Itataia mine concentrations. It also shows higher thorium values as well. (Author)