A field-based estimate of the zircon fission-track closure temperature

A field-based estimate of the zircon fission-track closure temperature is proposed from 13 zircon fission-track cooling ages of the Gold Butte block, SE Nevada. Using previously published and new thermochronological data, the thermal history of the Gold Butte block is re-evaluated, resulting in a geothermal-gradient estimate of 20.3 °C/km and a slow cooling rate of 0.55 ± 0.02 °C/m.y. from the Late Jurassic to the early Miocene before onset of rapid Miocene cooling. The rapidly cooled part of the Gold Butte block provides a slip rate of 10.5 km/m.y. of the hanging wall that caused the Miocene exhumation of this crustal section. Assuming these thermal conditions are correct, the closure temperature of the zircon fission-track system is determined at 205 ± 18 °C, which is in good agreement with previous field-based estimates. Because of the variation in zircon fission-track annealing behavior with radiation damage, field studies are a suitable way to calibrate the closure temperature of the zircon fission-track system.