Continental crust formation in the Southern Central Andes: new insights from O and Hf isotopes in zircon

ROSIE JONES; LINDA KIRSTEIN; SIMONE KASEMANN; BRUNO DHUIME; TIM ELLIOTT; VANESA D. LITVAK

Bristol

Encuentro; The Volcanic & Magmatic Studies Group; 2013

Geological Society of London and the Mineralogical Society

High resolution, in-situ oxygen and hafnium isotope analysis and U/Pb dating has been carried out on magmatic zircon obtained from Late Cretaceous to Late Miocene plutonics and volcanics, collected from an east-west transect across the Andean Cordillera. The information obtained from this mineral scale investigation has also been combined with thermobarometry and whole rock major/trace element geochemistry. Oxygen and hafnium isotope values obtained for Oligocene to Miocene magmatics, combined with the presence of inherited zircon populations, reflects the assimilation of different basement terranes as arc magmatism migrated to the east. This demonstrates varrying contamination of arc magmas with continental crust during the Cenozoic in relation to changing subduction zone geodynamics.