TY - JOUR
T1 - Implementation of an Alpha Damage Annealing Model for Zircon (U-Th)/He Thermochronology With Comparison to a Zircon Fission Track Annealing Model
AU - Guenthner, William R.
N1 - Publisher Copyright:
© 2020. American Geophysical Union. All Rights Reserved.
PY - 2021/2
Y1 - 2021/2
N2 - Radiation damage exerts a fundamental control on He diffusion in zircon, which manifests as correlations between (U-Th)/He date and effective uranium concentration. These correlations can be exploited with modeling to explore long-term thermal histories. This manuscript focuses on one such model, the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), https://doi.org/10.2475/03.2013.01, by integrating newly defined alpha damage annealing kinetics measured by Ginster et al. (2019), https://doi.org/10.1016/j.gca.2019.01.033, into ZRDAAM. I explore several consequences of this alpha damage annealing model as it relates to (U-Th)/He date-effective uranium (eU) correlations, using representative time-temperature paths and previously published results. Comparison between the current version of ZRDAAM, which uses fission track annealing, and the new annealing model demonstrates that, for thermal histories with prolonged periods at low temperatures (<50°C), alpha dose annealing kinetics yield slightly younger model dates at low to moderate eU concentrations, older dates at moderate to high eU, and substantially younger dates at the highest eU concentrations. The absolute eU concentrations over which the differences are observed varies for a given thermal history, so these ranges should be interpreted as relative or proportional. Younger model dates at high eU in most thermal histories result from lower amounts of annealing that occur with the Ginster et al. (2019) alpha dose annealing kinetics. This annealing model comparison illustrates that the choice of annealing kinetics has the greatest influence over model output for thermal histories involving either prolonged time periods in the 200–300°C temperature window, or a late-stage reheating event.
AB - Radiation damage exerts a fundamental control on He diffusion in zircon, which manifests as correlations between (U-Th)/He date and effective uranium concentration. These correlations can be exploited with modeling to explore long-term thermal histories. This manuscript focuses on one such model, the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), https://doi.org/10.2475/03.2013.01, by integrating newly defined alpha damage annealing kinetics measured by Ginster et al. (2019), https://doi.org/10.1016/j.gca.2019.01.033, into ZRDAAM. I explore several consequences of this alpha damage annealing model as it relates to (U-Th)/He date-effective uranium (eU) correlations, using representative time-temperature paths and previously published results. Comparison between the current version of ZRDAAM, which uses fission track annealing, and the new annealing model demonstrates that, for thermal histories with prolonged periods at low temperatures (<50°C), alpha dose annealing kinetics yield slightly younger model dates at low to moderate eU concentrations, older dates at moderate to high eU, and substantially younger dates at the highest eU concentrations. The absolute eU concentrations over which the differences are observed varies for a given thermal history, so these ranges should be interpreted as relative or proportional. Younger model dates at high eU in most thermal histories result from lower amounts of annealing that occur with the Ginster et al. (2019) alpha dose annealing kinetics. This annealing model comparison illustrates that the choice of annealing kinetics has the greatest influence over model output for thermal histories involving either prolonged time periods in the 200–300°C temperature window, or a late-stage reheating event.
KW - annealing
KW - radiation damage
KW - thermochronology
KW - zircon
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U2 - 10.1029/2019GC008757
DO - 10.1029/2019GC008757
M3 - Article
AN - SCOPUS:85101573885
SN - 1525-2027
VL - 22
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
IS - 2
M1 - e2019GC008757
ER -