Renewal: Mineral Physics Studies under the Pressure-Temperature Conditions of Earth's Deep Lower Mantle

研究人员相信，他们在地球深部地幔和铁核之间的极端压力-温度条件下发现了一个巨大的氧气储存库。储层由以前未知的铁超氧化物组成，可以突然释放出过量的氧气。在目前的项目中，团队将进一步探索不同类型的铁超氧化物，爆炸性氧气释放的条件以及氧气爆发的后果。这些零星的火山喷发提供了一种新的、统一的机制来回答一系列看似无关的过去事件的问题，这些事件发生在地球46亿年的历史中，塑造了现在这个有生命的星球。空气中的氧气从何而来？是什么导致了恐龙灭绝、哺乳动物出现的大灭绝？是什么推动所有大陆合并成一个单一的超级大陆，然后又将超级大陆分开形成独立的大陆？通过了解地球的过去和现在，我们可以洞察地球的未来。研究人员最近发现了具有黄铁矿型Pa3结构的高P-T铁超氧化物FeO2和FeO2Hx，这表明深部地幔矿物物理和地球动力学的潜在范式变化。该团队建议进一步研究超氧化物的高P-T矿物物理性质，包括将MgO2， AlO2和SiO2等其他主要成分掺入Pa3铁超氧化物中，其与硅酸盐桥锰矿和后钙钛矿的相互作用，其电子和磁性自旋态，以及铁和氧的价态。该团队将寻找除Pa3外的其他稳定结构类型的铁基超氧化物，这些超氧化物具有明显的铁氧化态3+，并确定它们的弹性波速，以便与地球深处的地震观测进行比较。该小组之前的研究表明，在地核-地幔边界存在大量富氧斑块。这项研究将调查这些巨大的氧气储层的亚稳态，以及当储存的氧气被释放时的后果，特别是由此产生的超级板块构造的地球动力学，这可能解释超级大陆合并和裂谷的起源。

The investigators believe they have discovered a giant oxygen reservoir at the extreme pressure-temperature conditions between the Earth's deep mantle and iron core. The reservoir consists of previously unknown iron superoxides which could suddenly release its excessive oxygen. In the present project, the team will further explore the different types of iron superoxides, the conditions for the explosive oxygen release, and the consequences of oxygen eruptions. The sporadic eruptions provide a new, unified mechanism for answering questions on a list of seemingly unrelated past events that occurred during Earth's 4.6 billion years history and shaped the present living planet. Where did the oxygen in the air come from? What caused the mass extinctions that killed the dinosaurs and ushered in the mammals? What was the driving force that pushed all continents to merge into a single supercontinent, and later pulled the supercontinent apart to form individual continents? From understanding the Earth's Past and Present, we may gain insights into the Earth's Future.The investigator's recent discovery of high P-T iron superoxides, FeO2 and FeO2Hx with the pyrite-type Pa3 structure has suggested potential paradigm changes in mineral physics and geodynamics of the deep lower mantle. The team proposes to further investigate the high P-T mineral physics properties of the superoxides, including the incorporation of other major components such as MgO2, AlO2 and SiO2 into the Pa3 iron superoxide, its interactions with silicate bridgmanite and post-perovskite, its electronic and magnetic spin states, and its valence states of iron and oxygen. The team will search for other stable structural types in addition to Pa3 for firon-based superoxides with the apparent Fe oxidation state 3+, and determine their elastic wave velocities for comparison for comparison with seismic observations in the deep Earth. The team's previous research suggested the existence of a massive amount of oxygen-rich patches at the core-mantle boundary. This research will investigate the metastability of such giant oxygen reservoirs, and the consequences when the stored oxygen is released, particularly the resulting geodynamics of the super plate tectonics that may explain the origin of merging and rifting of supercontinents.