Water-fluxed crustal melting produces Cordilleran batholiths

Most granites and related calc-alkaline silicic volcanic rocks from the United States and New Zealand Cordillera are saturated with zircon between 65 and 70 wt% SiO2. For this silica interval, zircon saturation temperatures ( T zr) are universally lower ( 900 °C). The values contrast with T zr from alkaline rocks from the Cenozoic U.S. Cordillera, which are typically >800 °C for 65–70 wt% SiO2. Case studies of titanium-in-zircon thermometry from...