Ne retention and slight enrichment of Kr–Xe relative to atmospheric levels have been found in biogenic chert samples. Previous studies suggested that the incorporation of noble gas atoms is dependent upon the structure rather than the environment. In this study, we perform molecular dynamics simulations of dissolved noble gas atomic diffusion through 1–4 nm diameter silica pores. Bulk-liquid-like water does not exist in the 1 nm diameter nanopores, which hinder noble gas diffusion into or out of the pores. In ≥2 nm diameter nanopores, noble gas atoms transport with bulk-liquid-like water into the center of the pores but size-controlled diffusive separation occurs at the layer of surface water and in the interior of the silica structure. The motion of large atoms (Kr and Xe) in surface water is governed by significant adsorption. Relatively small Ne atoms are able to cross the surface water layer and diffuse into the crystal interior. As a result of its moderate size and the negligible interaction with the interfacial surface, Ar lies beyond the adsorption and silica structure diffusion regimes. Therefore, our simulation results indicate that noble gas entrapment is expected to occur in nanoscale fluid circulation during sediment-to-chert lithification.

中文翻译：

---

二氧化硅纳米孔扩散过程中稀有气体分馏的分子动力学模拟

在生源石样品中发现了相对于大气水平的Ne保留和Kr–Xe的少量富集。先前的研究表明，稀有气体原子的掺入取决于结构而不是环境。在这项研究中，我们进行了溶解的稀有气体原子通过1-4 nm直径的二氧化硅孔的分子动力学模拟。直径为1 nm的纳米孔中不存在类似大块液体的水，这阻碍了稀有气体扩散到孔中或从孔中扩散出来。在直径≥2nm的纳米孔中，稀有气体原子与类似大块液体的水一起传输到孔的中心，但在表面水层和二氧化硅结构内部发生了尺寸受控的扩散分离。地表水中大原子（Kr和Xe）的运动受显着吸附的支配。相对较小的Ne原子能够穿过地表水层并扩散到晶体内部。由于其中等大小和与界面表面的相互作用可忽略不计，因此Ar超出了吸附和二氧化硅结构的扩散范围。因此，我们的模拟结果表明，在从沉积物到cher石的石化过程中，预计在纳米级流体循环中会发生稀有气体的截留。