Protracted felsic magmatic activity associated with the opening of the South Atlantic
Protracted felsic magmatic activity associated with the opening of the South Atlantic
Journal of the Geological Society of London (July 2001) 158, Part 4: 583-592
- absolute age
- Africa
- alkali feldspar
- Ar/Ar
- Atlantic Ocean
- Atlantic Ocean Islands
- basalts
- Cretaceous
- crust
- eruptions
- extrusive rocks
- feldspar group
- felsic composition
- flood basalts
- fractional crystallization
- framework silicates
- geochemistry
- hot spots
- igneous rocks
- lava
- Lower Cretaceous
- lower crust
- magmas
- magmatism
- melting
- melts
- Mesozoic
- middle crust
- mineral composition
- Namibia
- open systems
- petrography
- petrology
- plagioclase
- plate tectonics
- plumes
- Rio Grande Rise
- silicates
- South America
- South Atlantic
- Southern Africa
- tectonics
- Tristan da Cunha
- Uruguay
- volcanic rocks
- southern Uruguay
- Etendeka Province
- Parana Province
- felsic magmatism
Felsic magmatism is often observed in the final stages of the eruption of continental large igneous provinces. The occurrence of these felsic extrusive igneous rocks potentially provides key information on the complex interplay of magmatism and tectonics. In this paper we investigate the timing of eruption of Early Cretaceous felsic magmas associated with the Parana-Etendeka flood basalt province using the (super 40) Ar/ (super 39) Ar technique and interpret the results in terms of the recently proposed petrogenetic histories and dominant stress factors. There appears to be a link between lithospheric thinning and a change in the origin of the felsic magmas, from open system fractional crystallization to mid/lower crustal melting, particularly in southern Uruguay.
