Received: 25 Nov 2020 – Accepted for review: 14 Dec 2020 – Discussion started: 15 Dec 2020
Abstract. We conducted isochronal and isothermal annealing experiments on radiation-damaged zircons between 500 and 1000 °C for durations between ten minutes and five days. We measured the widths (Γ) and positions (ω) of the internal ν1(SiO4), ν2(SiO4), ν3(SiO4), and external rotation Raman bands at ~ 974, 438, 1008, and 356 cm−1. We fitted a Johnson-Mehl-Avrami-Kolmogorov and a distributed activation energy model to the fractional annealing data, calculated from the widths of the ν2(SiO4), ν3(SiO4), and external rotation bands. From the kinetic models, we determined closure temperatures Tc for damage accumulation for each Raman band. Tc range from 330 to 370 °C for the internal ν2(SiO4) and ν3(SiO4) bands; the external rotation band is more sensitive to thermal annealing (Tc ~ 260 to 310 °C). Our estimates are in general agreement with previous ones, but more geological evidence is needed to validate the results. The Tc difference for the different Raman bands offers the prospect of a multi-closure-temperature zircon Raman thermochronometer.
Supplementary material for Härtel, B., Jonkcheere, R., Wauschkuhn, B., Ratschbacher, L.: The closure temperature(s) of zircon Raman datingBirk Härtel https://doi.org/10.25532/OPARA-103
Birk Härtel et al.
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We carried out thermal annealing experiments between 500 and 1000 °C to determine the closure temperature of radiation-damage annealing in zircon (ZrSiO4). Our results show that the different Raman bands of zircon respond differently to annealing. The repair is highest for the external rotation Raman band near 356.6 cm−1. The closure temperature estimates range from 250 to 370 °C for different bands. The differences in closure temperatures offer the prospect of multi-T zircon Raman dating.
We carried out thermal annealing experiments between 500 and 1000 °C to determine the closure...