Reproducibility of Thermal History Reconstruction From Apatite Fission‐Track and (U‐Th)/He Data

Abstract

We report a new interlaboratory exercise to evaluate the reproducibility of apatite fission‐track (AFT) and (U‐Th)/He (AHe) data and thermal history analysis. Twelve laboratory groups participated, analyzing apatite separates from two previously studied localities. Ten groups returned AFT data from 13 analysts, five groups returned AHe data, one contributed apatite U/Pb data, and nine contributed thermal history models. Submitted AFT age data were generally consistent with the original studies and each other to within uncertainties, although there were departures, particularly among results obtained using laser ablation inductively coupled plasma mass spectrometry for uranium determination. AFT‐confined track‐length data showed more variation, which correlated between samples, suggesting that they may reflect analyst‐specific factors. Accounting for anisotropy using c axis projection reduced the variation and correlation. AHe ages showed more dispersion than observed in the previous studies, with one sample showing many ages consistent with prior work but also many significantly older ages, and the other roughly matching prior work but showing symmetrical scatter suggesting a 1SE uncertainty of 17–21%. Thermal history models generally agreed in their major features but showed considerable variation in detail, due to differences in data and data entry, model setup, and modeling software approach. Addressing pitfalls in data entry and model setup improved congruence, as would greater emphasis on AFT length and etch figure calibration. Because of scatter, AHe data had to be entered selectively into the models to achieve reasonable results. Although cautionary in several respects, study results point to promising avenues for improving the reproducibility of thermal history modeling.

Miocene Range Growth Along the Altyn Tagh Fault: Insights From Apatite Fission Track and (U‐Th)/He Thermochronometry in the Western Danghenan Shan, China

“…Some other evidence for the early Cenozoic deformation derive from single‐sample modeling of low‐temperature thermochornological data (e.g., Jolivet et al, ; D. Liu, Li, et al, ; Mock et al, ; Qi et al, ; J. Zhang et al, 2017). However, thermal history modeling, especially for single sample, may just provide one possible but not unique cooling history to produce the age and length distribution due to variation on reproducibility of fission track length data, data entry, model setup, and modeling software approach (Ketcham et al, , ). It strongly highlights the importance of collecting thermochronological samples systematically, such as along elevation profiles or based on tectonic deformation patterns.…”

Innovations in (U–Th)/He, Fission Track, and Trapped Charge Thermochronometry with Applications to Earthquakes, Weathering, Surface‐Mantle Connections, and the Growth and Decay of Mountains

“…Primary sources of analytical uncertainty in FT thermochronometry are undersaturation or oversaturation of FTs due to low or high U concentrations, respectively, and analyst bias in track counting and track length measurements (e.g., Donelick et al, 2005;Ketcham et al, 2015). Ketcham, van der Beek, et al (2018) provide a review of laboratory intercomparison of FT and (U-Th)/He dates and the sources of variability within each system and between the two systems.…”

Late Paleozoic Exhumation of the West Junggar Mountains, NW China

“…This is a commonly observed phenomenon in (U-Th)/He dating that stems from the many possible sources of uncertainty that can contribute to the variability of (U-Th)/He results (e.g. Green and Duddy, 2018;Ketcham et al, 2018;Wildman et al, 2016). Possible sources of uncertainty include the effect of grain size, radiation damage, grain breakage/fragmentation, zonation of parent isotopes, "bad neighbor" He implantation, and mineral or fluid inclusions (e.g.…”