深入下地幔:高温高压下的新反应与成分、结构分层  

Deep into the lower mantle:its new reactions,compositional changes,and structural layering under high temperature and high pressure

作　　者：孙宁宇 于英鑫 张馨月 毛竹[1,2,3] SUN Ning-yu;YU Ying-xin;ZHANG Xin-yue;MAO Zhu(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;CAS Center for Excellence in Comparative Planetology,University of Science and Technology of China,Hefei 230026,China;Frontiers Science Center for Planetary Exploration and Emerging Technologies,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026 [2]中国科学技术大学比较行星学卓越中心,合肥230026 [3]中国科学技术大学行星探索与新兴技术前沿科学中心,合肥230026

出　　处：《矿物岩石地球化学通报》2025年第1期28-36,I0002,共10页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金面上基金(42272036)。

摘　　要：本文总结了过去二十多年矿物学研究在下地幔结构相变和矿物反应的研究进展,集中讨论了富Ca布里奇曼石形成以及(Al,H)-SiO_(2)结构相变对下地幔物理性质、物质组成的影响。首先,讨论了富Ca布里奇曼石的形成条件,明确了过往研究中,温压条件及元素组成对其形成深度的影响存在的矛盾和问题。其次,指出该反应可能导致下地幔物相组成的分层,但其对下地幔速度密度与元素分配的影响尚需进一步研究。第三,通过总结俯冲洋壳中Al和水对SiO_(2)结构相变的影响,以及洋壳碳酸盐与SiO_(2)的反应,探讨了这些变化与下地幔中部不同深度和尺度的低速体之间的关系。最后,提出在地幔相关温压条件下进一步研究铝和水对SiO_(2)结构相变前后速度的影响,这对理解下地幔中部小尺度散射体的形成至关重要。In this paper,we have summarized the progresses in mineralogical researches over the past two decades regarding to the structural phase transitions and mineral reactions in the lower mantle,and emphatically discussed the formation of Ca-rich bridgmanite and the influence of its structural phase transitions of(Al,H)-SiO_(2),on the physical properties and chemical compositions of the lower mantle.Firstly,we have discussed the formation conditions of Ca-rich bridgmanite,clarified contradictions and problems in previous studies regarding to the influences of temperature,pressure,and elemental composition on the depth of the formation reaction of Ca-rich bridgmanite,suggested that this reaction could lead to stratification of phase compositions in the lower mantle,pointed out that its effects on the velocity,density,and element partitioning of the lower mantle should be further researched.By summarizing the influenece of Al and water on structural phase transitions of SiO_(2) in subducted oceanic crust and the reactions between carbonates and SiO_(2),we have further discussed relationships between these variations and the low velocity bodies in the middle part of the lower mantle at different depths and scales,and have proposed that further investigation of the influence of Al and water on the structural phase transitions of SiO_(2) under relevant mantle temperature and pressure conditions is crucial for understanding the formation of small-scaled scatterers in the middle part of the lower mantle.

关 键 词：下地幔 物质和结构分层 布里奇曼石-毛钙硅石互溶 斯石英 Al和水 

分 类 号：P589.1[天文地球—岩石学]