Heterogeneities, Anisotropy and Attenuation in the Deep Earth through Seismic waveform studies (HAADES)

通过地震波形研究地球深处的不均匀性、各向异性和衰减 (HAADES)

• 批准号: 289920201
• 负责人: Dr. Stephanie Durand
• 金额: --
• 依托单位: Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/289920201?language=en
• 关键词: Heterogeneities; Anisotropy; Attenuation; Deep; Earth

This project aims at understanding the causes for seismic structures in the lowermost mantle, the D" region, by using a novel combination of seismic observables and modelling. Combining differential attenuation measurements, anisotropy and velocity observables of phases sensitive to the lowermost mantle with 2D/3D modelling will provide a better constraint on the lowermost mantle mineralogy and dynamics. The region is difficult to access due to its large depth and the only way to reach such a deep region is through the use of seismic waves. The long wavelength structure of the lowermost mantle is fairly consistently constrained but during the last two decades shorter length scale features have been overprinted so that the structure of the D" region has become more complex and more intriguing. These smaller-scale features have been reported through regional studies that did not systematically investigate the same seismic parameters and often combinations of observables has not been attempted. A global map of the D" structure is thus still unavailable that would help to understand the origin of its seismic structure. That is why we propose in this project to perform measurements of various D" seismic properties (anisotropy, attenuation, seismic velocities and reflectors) on a global dataset with internally consistent techniques that will be taken together in a joint interpretation. The proposed project will improve our knowledge of the seismic anomalies within the D" region which is crucial to constrain the dynamics and mineralogy of the Earth. Our approach of combining differential attenuation, anisotropy and reflector depths/velocities is unique and the results are expected to have an important impact on a wide variety of disciplines: it will contribute to answer geodynamical questions such as material exchange across the Core-Mantle Boundary (CMB) and heat budget of the Earth and it will also constrain the lower mantle mineralogy.

该项目旨在通过使用地震观测和建模的新组合，了解最低地幔D”区域地震结构的原因。将差分衰减测量、各向异性和对最下部地幔敏感的相位的速度可观测值与2D/3D建模相结合，将对最下部地幔矿物学和动力学提供更好的约束。该区域由于深度大而难以进入，到达如此深的区域的唯一方法是通过使用地震波。最低地幔的长波长结构相当一致地受到限制，但在过去的二十年中，较短的长度尺度特征被叠加，使得D”区域的结构变得更加复杂和有趣。这些较小规模的特征是通过区域研究报告的，这些研究没有系统地调查相同的地震参数，而且往往没有尝试将可观测数据组合起来。因此，D”结构的全球地图仍然无法获得，这将有助于了解其地震结构的起源。这就是为什么我们在这个项目中建议在全球数据集上使用内部一致的技术对各种D”地震属性（各向异性、衰减、地震速度和反射体）进行测量，这些技术将在联合解释中一起使用。拟议的项目将提高我们对D”区域内地震异常的认识，这对限制地球的动力学和矿物学至关重要。我们的方法相结合的差分衰减，各向异性和反射层深度/速度是独特的，其结果预计将产生重要影响的各种学科：它将有助于回答地球动力学问题，如跨核幔边界（CMB）的物质交换和地球的热收支，它也将约束下地幔矿物学。