Protracted felsic magmatic activity associated with the opening of the South Atlantic

Felsic magmatism is often observed in the final stages of the eruption of c ontinental large igneous provinces. The occurrence of these felsic extrusiv e igneous rocks potentially provides key information on the complex interpl ay of magmatism and tectonics. In this paper Lye investigate the timing of eruption of Early Cretaceous felsic magmas associated with the Parana-Etend eka flood basalt province using the Ar-40/Ar-39 technique and interpret the results in terms of the recently proposed petrogenetic histories and domin ant stress factors. There appears to be a link between lithospheric thinnin g and a change in the origin of the felsic magmas, from open system Fractio nal crystallization to mid/lower crustal melting, particularly in southern Uruguay.