What is the temperature and composition of the lowermost mantle?

最下地幔的温度和成分是多少？

• 批准号: 2696813
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2696813
• 关键词: What; temperature; composition; lowermost; mantle

The two large low-velocity provinces (LLVPs) are key features in the lowermost mantle, covering 25 % ofthe core surface and rising 100s of km above the core-mantle boundary (CMB). Given their size, theirproperties impact several planetary-scale processes including mantle convection, thermal evolution,mixing of chemical heterogeneity, and ultimately plate tectonics. Their physical properties can also beused to constrain possible hypotheses of their origin. LLVPs could be hot regions with concentratedmantle plumes, or chemically distinct dense structures sculpted by mantle convection. Most existingstudies assume identical physical properties between the Pacific and African LLVPs, yet their differencescannot be ignored (Garnero et al., 2016). Understanding the properties and origins of the two LLVPs isthus important for resolving conflicting perspectives of the lowermost mantle between different scientificfields. For example, the latter hypothesis provides a viable explanation to the disagreement of the Ureyratio of 0.7 in geophysics and 0.3 in geochemistry (Labrosse et al., 2007)

两个大的低速区（LLVP）是最下地幔的关键特征，覆盖了地核表面的 25%，并高出核-地幔边界（CMB）数百公里。考虑到它们的大小，它们的特性会影响几个行星尺度的过程，包括地幔对流、热演化、化学不均匀性的混合，以及最终的板块构造。它们的物理特性也可用于限制其起源的可能假设。 LLVP可能是具有集中地幔羽流的热区域，或者是由地幔对流塑造的化学上不同的致密结构。大多数现有研究假设太平洋和非洲 LLVP 具有相同的物理性质，但它们的差异不容忽视（Garnero 等，2016）。因此，了解这两个 LLVP 的性质和起源对于解决不同科学领域之间关于地幔下层的相互冲突的观点非常重要。例如，后一种假设为地球物理学中 Ureyratio 为 0.7 和地球化学中 0.3 的不一致提供了可行的解释 (Labrosse et al., 2007)