Muscovite ranks among the most commonly dated minerals in ${}^{40}$Ar/${}^{39}$Ar geochronology. Yet, its use in thermochronological reconstructions is hampered by the lack of reliable data on its ${}^{40}$Ar diffusional behavior. In this contribution, we investigate ${}^{40}$Ar lattice diffusion in muscovite at the atomic scale using Molecular Dynamics (MD) simulations combined with Nudged Elastic Band (NEB) and Transition State Theory (TST). Classical MD simulations of ${}^{40}$Ar recoil dynamics in $2M_1$ muscovite reveal that ${}^{40}$Ar initially resides predominantly in the interlayer region, close to its production site. Systematic computations of migration barriers coupling NEB with TST identify the divacancy mechanism as the more energetically favorable pathway for ${}^{40}$Ar diffusion in the interlayer region, with characteristic enthalpy of motion $E=66$ kcal.mol^-1 and vibrational entropy term $D_0=6\times {10}^{-4}$ cm².s^-1. For typical cooling rates between 1$-$100 $°$C.Ma^-1 and grain size varying from 0.1 and 1 mm, these parameters predict closure temperatures significantly higher ($\sim$ 200 $°$C) than currently accepted maximum estimates ($\sim$ 500 $°$C). Consistent with long-standing empirical evidence, our theoretical results downplay the role of purely thermally activated diffusion in promoting efficient ${}^{40}$Ar transport in ideal (stoichiometrically stable and undefective) muscovite. Along with experimental and field-based evidence, they call for more complex physics to explain the ${}^{40}$Ar retention properties of natural muscovite, most notably by considering crystal-chemical disequilibrium interactions and the reactivity of the interlayer with the external medium.

白云母是最常见的矿物之一${}^{40}$氩气/${}^{39}$Ar 地质年代学。然而，由于缺乏可靠的数据，阻碍了它在热年代重建中的应用。${}^{40}$Ar 扩散行为。在这篇文章中，我们调查${}^{40}$使用分子动力学 (MD) 模拟结合轻推弹性带 (NEB) 和过渡态理论 (TST) 在原子尺度上的白云母中的 Ar 晶格扩散。经典的 MD 模拟${}^{40}$Ar反冲动力学$2{米}_1$莫斯科人透露${}^{40}$Ar最初主要存在于靠近其生产地点的夹层区域。将 NEB 与 TST 耦合的迁移障碍的系统计算确定了缺位机制是更有利的途径${}^{40}$层间区域的 Ar 扩散，具有特征运动焓$乙=66$kcal.mol ^-1和振动熵项$D_0=6\times {10}^{-4}$厘米² .s ^-1。对于 1 之间的典型冷却速率$-$100$°$C.Ma ^-1和晶粒尺寸从 0.1 到 1 毫米不等，这些参数预测闭合温度显着更高（$～$200$°$C) 比目前接受的最大估计值 ($～$500$°$C）。与长期的经验证据一致，我们的理论结果淡化了纯热激活扩散在促进高效${}^{40}$理想（化学计量稳定且无缺陷）白云母中的 Ar 传输。除了实验和实地证据外，他们还呼吁使用更复杂的物理学来解释${}^{40}$天然白云母的 Ar 保留特性，最显着的是考虑晶体-化学不平衡相互作用和中间层与外部介质的反应性。