Implications for Timing of Andean Uplift from Thermal Resetting of Radiation‐Damaged Zircon in the Cordillera Huayhuash, Northern Peru

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Abstract The Cordillera Huayhuash is a north‐south‐oriented range along the drainage divide of the northern Peruvian Andes. The range has high topography with peaks in excess of 5500 m and the second‐highest peak in Peru, Nevados Yerupaja (6617 m). Bedrock is dominated by folded Mesozoic miogeoclinal rocks unconformably overlain by mid‐Tertiary volcanics intruded by Late Tertiary granitic rocks and silicic dikes. Zircon fission track (ZFT) and (U‐Th)/He (ZHe) dating of zircons along a west‐east transect elucidates the thermal evolution of exhumed and uplifted rocks. The stability of fission tracks in zircons is a function of single‐grain radiation damage. In samples with grain‐to‐grain variability in radiation damage, resetting results in variable resetting and multiple age populations. Low retentive zircons (LRZs), which have a partly disordered crystalline structure, have significant radiation damage and a low temperature of annealing (ca. 180°–200°C). High retentive zircons (HRZs), which are nearly cry...