Abstract

The lifespan of magmatic-hydrothermal activity that results in large and economically viable porphyry copper deposits remains poorly described. Here, we estimate the duration of the magmatic-hydrothermal fluid flow at 700 °C to <350 °C using diffusion profiles of Ti and δ18O in quartz from Fe, Cu, and Mo sulfide-bearing hydrothermal veins and porphyry dikes at the Haquira East porphyry copper deposit, Peru. In situ measurements indicate all vein quartz is zoned in Ti (1–120 ppm), whereas high-temperature quartz has been re-equilibrated at 450 °C to δ18O = 10.7‰. We use diffusion modeling to reproduce the observed Ti and δ18O profiles, which provides lifespan estimates at Haquira of 75–170 k.y. for the period from initial magma and fluid injection at 700 °C to cooling below 350 °C. The bulk of the Cu-Mo-Au ore formed in ≤35 k.y., indicating that large-scale, economic porphyry copper deposits can form rapidly.

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