Towards imaging flow at the base of the mantle with seismic, mineral physics and geodynamic constraints
Towards imaging flow at the base of the mantle with seismic, mineral physics and geodynamic constraints
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DOI：
10.1002/essoar.10507848.1
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
A. Nowacki;S. Cottaar
中科院分区：
文献类型：
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作者：
A. Nowacki;S. Cottaar
也许地幔对流的最不模糊的信号来自对地震各向异性的观察——波速随方向的变化——这必然是由于变形发生时材料的有序化而产生的。因此，多年来人们付出了巨大的努力来从这些数据推断地幔流的方向和性质。观测主要集中在地幔的边界层，这里的变形预计最强，并且通常存在各向异性。虽然绘制流程的前景看起来不错，但目前对几个关键问题缺乏了解阻碍了进展。其中包括最下地幔各向异性的成因、致病物质对剪切的响应以及致病物质的单晶或相地震特性。在本章中，我们回顾了最近对最低地幔各向异性的观测、对矿物弹性和变形机制的限制，以及将地球动力学模型与地震观测联系起来的挑战。
Perhaps the least ambiguous signal that the mantle is convecting comes from observations of seismic anisotropy – the variation of wave speed with direction – which must arise due to the ordering of material as deformation occurs. Therefore, significant effort has been made over many years to infer the direction and nature of mantle flow from these data. Observations have focused on the boundary layers of the mantle, where deformation is expected to be strongest and where anisotropy is usually present. While prospects for mapping flow seem good, the lack of knowledge of several key issues currently holds back progress. These include the cause of anisotropy in the lowermost mantle, the causative material's response to shear, and the single‐crystal or ‐phase seismic properties of the causative materials. In this chapter we review recent observations of lowermost mantle anisotropy, constraints on mineral elasticity and deformation mechanisms, and challenges in linking geodynamic modeling with seismic observations.