δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth, remaining stable under the extreme conditions throughout the mantle. The behavior of δ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle. δ-(Al_0.95Fe_0.05)OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells. The incorporation of 5 mol% FeOOH increases the unit-cell volume of δ-AlOOH by ∼1% and decreases the shear-wave velocity (V_S) by ∼5% at 20–135 GPa. In particular, the compressional (V_P) and shear (V_S) wave velocities of δ-(Al_0.95Fe_0.05)OOH are 7%–16% and 10%–24% greater than all the major minerals in the mantle transition zone including wadsleyite, ringwoodite, and majorite. The distinctly high sound velocities of δ-(Al_0.95Fe_0.05)OOH at 20–25 GPa may contribute to the seismic anomalies observed at ∼560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea. Furthermore, the V_S of δ-(Al_0.95Fe_0.05)OOH is about 10% and 4%−12% lower than iron-bearing bridgmanite Mg_0.96Fe_0.05Si_0.99O₃ and ferropericlase (Mg_0.92Fe_0.08)O, respectively, under the lowermost mantle conditions, which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.

δ-（Al，Fe）OOH被认为是地球上最重要的含水相之一，在整个地幔的极端条件下仍保持稳定。δ-（Al，Fe）OOH在高压下的行为对于理解深水循环至关重要。通过高压布里渊光散射光谱和高达135.4 GPa的同步辐射X射线衍射研究了在21 GPa和1473 K下合成的δ-（Al _0.95 Fe _0.05）OOH晶体。在20–135 GPa时，掺入5 mol％的FeOOH会使δ-AlOOH的晶胞体积增加约1％，并使剪切波速度（V _S）降低约5％。特别是压缩力（V _P）和剪切力（V _S）δ-（Al _0.95 Fe _0.05）OOH的波速比地幔过渡带中的所有主要矿物（包括瓦兹利石，林木和主要矿物）高7％–16％和10％–24％。δ-（Al _0.95 Fe _0.05）OOH在20–25 GPa处明显较高的声速，可能有助于在伊豆邦宁和/或韩国下方的冷，停滞平板中约560至680 km的深度处观察到地震异常。此外，δ-（Al _0.95 Fe _0.05）OOH的V _S比含铁的水辉锰矿Mg _0.96 Fe _0.05 Si _0.99 O ₃和亚铁镁锰矿（Mg _0.92）低约10％和4％-12％在最低地幔条件下分别为Fe _0.08）O，这可能部分有助于下部地幔底部的大型低剪切速度省和超低速带。