Figure 19. Reconstruction of the regional setting of the volcanic rocks and massive sulfide deposits of the Aljustrel area. View is to the northwest. The host volcanic sequence is of Early Carboniferous age, and is assumed to overlie the Phyllite-Quartzite Group (not seen at Aljustrel, but forming the basement to other VMS deposits in the Iberian Pyrite Belt). The Feitais and Estacao lie within the eastern anticline at Aljustrel, whereas the St. Joao and Moinho deposits lie within the western anticline. The nature of the felsic footwall differs in these two areas. A large mass of quartz-feldspar porphyry which occurs in the central Aljustrel area is interpreted as a largely subvolcanic intrusion, although in the Moinho area it may have fed shallow sills and thin flows. The quartz-feldspar porphyry was emplaced after sulfide deposition in this model.



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