Sound Velocities of Al‐Bearing Phase D up to 22 GPa and 1300 K
Sound Velocities of Al‐Bearing Phase D up to 22 GPa and 1300 K
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DOI：
10.1029/2020gl088877
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发表时间：
2020-09
影响因子：
5.2
通讯作者：
Chaowen Xu;S. Gréaux;T. Inoue;M. Noda;Wei Sun;H. Kuwahara;Y. Higo
中科院分区：
文献类型：
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作者：
Chaowen Xu;S. Gréaux;T. Inoue;M. Noda;Wei Sun;H. Kuwahara;Y. Higo
在22 GPa和1300 K下使用原位同步加速器X射线技术结合多砧装置中的超声测量研究了含Al相D的声速。发现含Al相D的等温体积模量比Mg端元的等温体积模量低约16.7%，表明Al掺入对相D的体积模量有很强的影响。含Al相D与其他地幔过渡带矿物相比具有更高的P-（VP）和S-（VS）波速度，与含水含铁的林伍德石相比，VP高达4.3%，VS高达9.6%，这可能导致无水地幔和含水板片组分之间的速度差异减小。在下地幔最上部，携带Al相D的水合板状组分的积累可以解释一些高达-1.5%的局部负剪切速度扰动（ΔVS），尽管ΔVP（-0.5%）预计仍低于地震学技术的检测极限。
Sound velocities of Al‐bearing phase D were investigated up to 22 GPa and 1300 K using in situ synchrotron X‐ray techniques combined with ultrasonic measurements in a multianvil apparatus. The isothermal bulk modulus of Al‐bearing phase D was found to be ~16.7% lower than that of Mg‐endmember, suggesting a strong effect of Al incorporation on the bulk modulus of phase D. Al‐bearing phase D has higher P‐ (VP) and S‐ (VS) wave velocities compared to other mantle transition zone minerals, up to 4.3% for VP and up to 9.6% for VS compared with hydrous iron‐bearing ringwoodite, which might engender reduction of velocity contrast between anhydrous mantle and hydrous slab components. The accumulation of hydrated slab components carrying Al‐phase D in the uppermost lower mantle can explain some local negative shear velocity perturbations (ΔVS) up to −1.5%, although ΔVP (−0.5%) is expected to remain below the detection limit of seismological techniques.