CSEDI: Structure and Dynamics of Large-Scale Lower Mantle Compositional Heterogeneity

CSEDI：大规模下地幔成分异质性的结构和动力学

• 批准号: 1161038
• 负责人: Edward Garnero
• 金额: $ 22.03万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-15 至 2015-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1161038&HistoricalAwards=false
• 关键词: CSEDI; Structure; Dynamics; Large; Scale

This two-year proposal focuses on seismological imaging of lower mantle heterogeneity beneath the Pacific Ocean, and numerical convection simulations to put the seismic imaging into a dynamically consistent framework. Our approach is multidisciplinary, and combines seismological analyses by PI Garnero with geodynamical convection simulations by PI McNamara. Recent seismological work has added great detail to deep mantle structure beneath the Pacific, with evidence for large low shear velocity provinces (LLSVPs) that are denser than and chemically distinct from the surrounding mantle. Smaller scale structure includes ultra-low velocity zones (ULVZs) that may preferentially reside at LLSVP margins. Our high resolution seismological experiments aim to better resolve sharp LLSVP edges that appear to extend well up off the core-mantle boundary (CMB), and associated phenomena that depend strongly on LLSVP and mantle properties, including: ULVZ location and structure, CMB topography in vicinity of LLSVP edge, strong heterogeneity within the LLSVP, and relationship to plume upwelling off the LLSVP top. We are focusing on seismic data from southwest Pacific subduction zones recorded in North American, since they densely sample the LLSVP beneath the Pacific Ocean, especially beneath Hawaii. This is a focus area of the proposed work. The seismic findings will inform and be informed by geodynamic simulations that include LLSVP structures. Particular attention will be given to LLSVP morphology and internal structure in the dynamical calculations, as these features will be seismically imaged. Better imaging and modeling LLSVPs will help move us forward in understanding Earth's thermal and mass transport mechanisms, and hence the driving forces in convection that shape the deep structures. Better understanding the nature of convective flow in Earth's deep mantle, how that flow shapes plausible deep and dense compositional reservoirs, and return flow mass transfer that includes plumes is an underlying motivation in this work.This work is important for understanding the structure and dynamics of Earth's deep interior. The nature of convective flow in Earth?s deep mantle, how that flow shapes plausible deep and dense compositional reservoirs, and return flow mass transfer that includes plumes is of interest to the vast spectrum of Earth and planetary scientists. The funding is for a geodynamics graduate student who will be trained on an interdisciplinary research project, and a postdoctoral researcher focused on seismic imaging and geodynamics computations. The PIs are experienced at co-mentoring students and postdocs in a cross-disciplinary fashion.

这项为期两年的建议着重于太平洋下面地幔异质性的地震异质性以及数值对流模拟将地震成像置于动态一致的框架中。 我们的方法是多学科的，并将Pi Garnero的地震学分析与Pi McNamara的地球动力学对流模拟相结合。最近的地震学研究为太平洋下面的深层地幔结构提供了很大的细节，并有证据表明，大型低剪切速度省（LLSVP）比与周围地幔的化学差异更密集。 较小的规模结构包括可能位于LLSVP边缘的超低速度区（ULVZ）。我们高分辨率的地震实验旨在更好地解决尖锐的LLSVP边缘，这些边缘似乎远离了核心膜边界（CMB），以及相关的现象，这些现象在很大程度上取决于LLSVP和地幔特性，包括：ULVZ的位置和结构，CMB在LLSVP Edge of LLSVP Edge of Llsvp extrangion in necter and in efters and the Offlys intery intery intery intery intery newnerigenty and in e; LLSVP顶部。我们关注的是来自北美地区西南太平洋俯冲带的地震数据，因为它们密集地对太平洋（尤其是夏威夷下方）的LLSVP进行了密集的样品。 这是拟议工作的重点领域。 地震发现将通过包括LLSVP结构在内的地球动力学模拟告知和告知。 在动态计算中，将特别注意LLSVP的形态和内部结构，因为这些特征将在地震成像上成像。更好的成像和建模LLSVP将有助于我们向我们前进，以了解地球的热和质量传输机制，从而塑造深层结构的对流中的驱动力。 更好地理解了地球深地幔中对流流的性质，该流动如何塑造合理的深层和密集的组成储层，以及包括羽毛在内的返回流量质量转移是这项工作中的基本动机。这项工作对于理解地球深层内部的结构和动力学非常重要。地球深地幔中对流流的性质，这种流动如何形成合理的深层和密集的组成储层，以及包括羽毛在内的返回流量传质，这是地球和行星科学家的广泛范围。这笔资金是针对地球动力学研究生的资金，该研究生将接受跨学科研究项目的培训，以及专注于地震成像和地球动力学计算的博士后研究人员。 PI以跨学科的方式在授课学生和博士后方面经验丰富。