Apatite fission‐track analysis of Cretaceous alkaline rocks of Ponta Grossa and Alto Paranaíba Arches, Brazil

This work presents fission-track ages and thermal history modelling of apatite samples from two Brazilian alkaline formations: Alto Paranaiba and Ponta Grossa Arches. The apatite fission-track ages obtained for Alto Paranaiba Arch agree with those determined by other radiometric dating methods presenting higher closure temperatures. The ages given by the fission-track thermochronometer suggest that no strong tectonic event has occurred after Alto Paranaiba Formation during Upper Cretaceous. This event is also supported by thermal history modelling of this arch, which is characterized by fast cooling followed by residence at lower temperatures. On the other hand, apatite fission-track ages from Ponta Grossa Arch are systematically lower than other radiometric ages, suggesting that at least one tectonic event occurred after Ponta Grossa Formation, around 130Ma. Copyright (c) 2015 John Wiley & Sons, Ltd.