Halite traps inclusions of the mother fluid when precipitating. When unchanged, the density of these fluid inclusions (FIs) records the water temperature T_f at the time of crystal formation. As halite is ubiquitous on Earth and geological time, its FIs possess a high potential as temperature archives. However, the use of FIs in halite as an accurate palaeothermometer has been hampered due to limitations of microthermometry, the most commonly used analytical method. Here, we show how Brillouin spectroscopy in halite FIs bypasses these limitations and allows recovering T_f to within 1 °C or less. To demonstrate this, we measured samples synthesised at 24.6 ± 0.5 °C and 33 ± 1 °C, and obtained 24.8 ± 0.4 °C and 31.9 ± 0.4 °C, respectively. This novel approach thus provides an accurate palaeothermometer for lacustrine and marine environments. Moreover, Brillouin spectroscopy solves the long‐standing debate on damage of halite fluid inclusions through quantifying the acceptable temperature excursion for preserving elastic behaviour: [l/(1 µm)]^−0.64 × (90 °C), where l is the FI size. This threshold is lower for FIs close to the surface of the host crystal or to another FI. We also list ‘best practices’ for applying both microthermometry and Brillouin thermometry.

中文翻译：

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将卤石流体包裹体恢复为精确的古温度计：布里渊温度计与微量温度计

沉淀时，卤石会捕获母液中的夹杂物。如果不变，这些流体夹杂物（FIs）的密度将记录晶体形成时的水温T _f。由于盐岩在地球和地质时代无处不在，因此其FIs具有很高的温度档案潜力。但是，由于最常用的分析方法-显微温度计的局限性，阻碍了将岩盐中的FIs用作精确的古温度计。在这里，我们展示了盐岩FI中的布里渊光谱如何绕过这些限制并允许回收T _f低于1°C。为了证明这一点，我们测量了在24.6±0.5°C和33±1°C下合成的样品，分别获得了24.8±0.4°C和31.9±0.4°C。因此，这种新颖的方法为湖水和海洋环境提供了一种精确的古温度计。此外，布里渊光谱通过量化可接受的温度偏移以保留弹性行为，解决了有关盐石流体夹杂物损坏的长期争论：[ l /（1 µm）] ^-0.64  ×（90°C），其中l是FI尺寸。对于接近主体晶体表面或另一个FI的FI，此阈值较低。我们还列出了同时使用微量温度计和布里渊温度计的“最佳实践”。