Xie Tianqi, Shieh Sean R, Chariton Stella, van Zyl Mauritz, Rodriguez Ricardo D, Prakapenka Vitali B, Zhang Dongzhou
Department of Earth Sciences, University of Western Ontario, London, ON N6K 5B7, Canada.
Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
Sci Adv. 2025 Jun 20;11(25):eadv8231. doi: 10.1126/sciadv.adv8231.
Diaplectic glass and maskelynite in shocked plagioclase serve as key diagnostic features for high level of shock metamorphism in impact craters and meteorites. However, their formation mechanisms remain unclear and have long been argued, mainly due to the lack of phase diagram for plagioclase with extended pressure-temperature conditions. We report the stabilities of labradorite and anorthite at pressure up to 65 gigapascals and temperature up to 4000 kelvin. Our experimental results reveal the pressure-temperature conditions for amorphization, decomposition, and melting of labradorite and anorthite. The boundary between amorphous plagioclase and crystalline high-pressure phases in our phase diagram indicate diaplectic glass can form at 1300 to 1500 kelvin, and the melting line suggests that maskelynite can be generated above 3000 kelvin at high pressures. Formation conditions of diaplectic glass and maskelynite in plagioclase-bearing rocks are also suggested by the combination of phase diagram and shock Hugoniot data. These findings will advance our understanding of the bombardment history on rocky planetary surfaces.
冲击斜长石中的透辉玻璃和熔合成因斜长石是撞击坑和陨石中高程度冲击变质作用的关键诊断特征。然而，它们的形成机制仍不清楚，长期以来一直存在争议，主要原因是缺乏涵盖更广泛压力 - 温度条件的斜长石相图。我们报告了拉长石和钙长石在高达65吉帕斯卡的压力和高达4000开尔文的温度下的稳定性。我们的实验结果揭示了拉长石和钙长石非晶化、分解和熔化的压力 - 温度条件。我们相图中无定形斜长石与结晶高压相之间的边界表明，透辉玻璃可在1300至1500开尔文形成，而熔化线表明在高压下高于3000开尔文可产生熔合成因斜长石。相图和冲击雨贡纽数据的结合也表明了含斜长石岩石中透辉玻璃和熔合成因斜长石的形成条件。这些发现将推动我们对岩石行星表面撞击历史的理解。
