The phase relations of iron-rich olivine and its high-pressure polymorphs are important for planetary science and meteoritics because these minerals are the main constituents of terrestrial mantles and meteorites. The olivine–ahrensite binary loop was previously determined by thermochemical calculations in combination with high-pressure experiments; however, the transition pressures contained significant uncertainties. Here we determined the binary loop of the olivine–ahrensite transition in the (Mg,Fe)₂SiO₄ system at 1740 K in the pressure range of 7.5–11.2 GPa using a multi-anvil apparatus with the pressure determined using in situ X-ray diffraction, compositional analysis of quenched run products, and thermochemical calculation. Based on the determined binary loop, a user-friendly software was developed to calculate pressure from the coexisting olivine and ahrensite compositions. The software is used to estimate the shock conditions of several L6-type chondrites. The obtained olivine–ahrensite phase relations can also be applied for precise in-house multi-anvil pressure calibration at high temperatures.

富含铁的橄榄石及其高压多晶型物的相关系对行星科学和陨石学很重要，因为这些矿物是地球地幔和陨石的主要成分。橄榄石-阿伦石二元环先前是通过热化学计算结合高压实验确定的；然而，转型压力包含很大的不确定性。在这里，我们确定了 (Mg,Fe) ₂ SiO _{4 中}橄榄石-阿伦石转变的二元环系统在 1740 K 和 7.5-11.2 GPa 的压力范围内使用多砧装置使用原位 X 射线衍射、淬火运行产品的成分分析和热化学计算确定压力。基于确定的二元环，开发了一个用户友好的软件来计算共存橄榄石和阿伦石组合物的压力。该软件用于估计几种 L6 型球粒陨石的冲击条件。获得的橄榄石-阿伦石相关系也可用于在高温下进行精确的内部多砧压力校准。