近日，美国德州农工大学Jin S. Zhang团队报道了毛河光石的弹性是下地幔非均质性的主要因素。这一研究成果于2025年11月27日发表在《科学》杂志上。

地幔中俯冲的洋中脊玄武岩（MORB）的地球物理检测受到阻碍，原因是其关键成分含铁、铝、镁、钛的毛河光石的弹性不确定性。研究组利用布里渊光谱学和X射线衍射，测定了Ca0.906(1)Fe2+0.027(1)Fe3+0.042(1)Mg0.033(1)Al0.072(1)Ti0.020(1)Si0.912(1)O3毛河光石在113吉帕和2294开尔文下的弹性。

结果显示，其剪切波速度比端元毛河光石慢10%至20%，成为地幔主要矿物中速度最慢的相。模型表明，含20至25体积百分比毛河光石的MORB可能构成大尺度低剪切波速省（LLSVPs），而从基底岩浆海洋结晶的富含毛河光石的堆积层或为超低速带（ULVZs）。毛河光石对不相容和生热元素的承载能力可能将LLSVPs和ULVZs与地幔柱起源及洋岛玄武岩的地球化学特征联系起来。

附：英文原文

Title: Elasticity of davemaoite as a primary contributor to lower-mantle heterogeneities

Author: Wen-Yi Zhou, Ming Hao, Wenhao Su, Taehyun Kim, Sibo Chen, Sang-Heon Shim, Dongzhou Zhang, Phuong Q. H. Nguyen, Katherine Armstrong, Jin S. Zhang

Issue&Volume: 2025-11-27

Abstract: Geophysical detection of subducted mid–ocean ridge basalt (MORB) in the lower mantle is hindered by uncertainties in the elasticity of Fe,Al,Mg,Ti–bearing davemaoite, a key MORB component. Using Brillouin spectroscopy and x-ray diffraction, we determined the elasticity of a Ca0.906(1)Fe2+0.027(1)Fe3+0.042(1)Mg0.033(1)Al0.072(1)Ti0.020(1)Si0.912(1)O3 davemaoite up to 113 gigapascals and 2294 K. We found that it exhibited a shear wave velocity 10 to 20% slower than end-member davemaoite, making it the slowest phase among major lower-mantle minerals. Our models show that MORB, containing 20 to 25 volume percent davemaoite, potentially contributes to large low-shear-velocity provinces (LLSVPs), whereas a cumulate layer enriched in davemaoite crystallized from basal magma ocean may comprise ultralow-velocity zones (ULVZs). Davemaoite’s ability to host incompatible and heat-producing elements possibly links LLSVPs and ULVZs to mantle plume initiation and geochemical signatures of ocean island basalts.

DOI: adx8356

Source: https://www.science.org/doi/10.1126/science.adx8356