CSEDI Collaborative Research: Understanding the origins of MORB geochemical heterogeneity using constraints from seismic tomography and geodynamic modeling

CSEDI 合作研究：利用地震层析成像和地球动力学建模的约束了解 MORB 地球化学非均质性的起源

• 批准号: 1800450
• 负责人: Maxwell Rudolph
• 金额: $ 38.14万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1800450&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; Understanding; origins

The chemical composition of lavas erupted under the water at mid ocean ridges, where new seafloor is created as tectonic plates spread apart, is influenced by the temperature and composition of the underlying mantle from which these melts are generated. The proposed work examines correlations between mid ocean ridge basalt (MORB) chemistry and images of Earth's interior produced using seismic tomography. It uses large-scale numerical models of mantle flow to connect surface observations with past and present mantle structure. The proposed work has three components. First, it examines the distributions of helium isotopes and other geochemical indicators of mantle temperature at spreading centers and how these are related to temperature and compositional variations in the sub-oceanic mantle. Second, it explores the flow history of mantle material that is sampled at spreading centers. Third, it addresses how the mid ocean ridges in different ocean basins have sampled the mantle since the breakup of the supercontinent Pangea. The project will provide new information about how variations in seismic velocity beneath the ocean basins are related to the variations in chemical composition of MORB, and how upper mantle variations in composition and temperature are related to deeper mantle structure.Different disciplines make distinct contributions to our understanding of the dynamics of Earth's mantle. In particular, relating the distribution of geochemical and seismological heterogeneity at the global scale has been a challenge because of the different wavelengths sampled in these two types of approaches: local, for geochemistry, long wavelength, for seismology. Recently, progress has been made in both fields, with resolution reaching sub-1000 km scale in global seismic tomography, and a more complete geochemical sampling along mid-ocean ridges, allowing the investigation of patterns at wavelengths commensurate with the seismic imaging. Concurrently, progress has been made in developing methodologies for realistic geodynamic modeling of mantle circulation in 3D, incorporating constraints from seismology and surface observables (e.g. plate motions, topography, and the geoid). Tying these elements together to better constrain the flow history of material sampled at ridges is becoming feasible at the present time. The proposed work will produce new geochemical datasets, tomographic models, and results from geodynamic models that will be distributed to the broader geoscience community for further analysis and in a format that permits immersive 3D visualization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

熔岩的化学成分在海脊的水下爆发，在那里创建了新的海底，因为构造板分开，受到了基础地幔的温度和成分的影响，从中产生了这些熔体。拟议的工作研究了使用地震层析扫描产生的地球内部的海洋脊（MORB）化学和地球内部图像之间的相关性。它使用地幔流的大规模数值模型将表面观测与过去和现在的地幔结构联系起来。拟议的工作有三个组成部分。首先，它检查了扩散中心时地幔温度的氦同位素和其他地球化学指标的分布，以及这些分布与亚偏移地幔中的温度和组成变化如何相关。其次，它探讨了在扩散中心进行采样的地幔材料的流史。第三，它介绍了自超大陆Pangea分手以来，不同海盆中的中海脊是如何取样了地幔的。该项目将提供有关海盆下地震速度的变化如何与MORB化学成分的变化有关的新信息，以及组成和温度的上地幔变化与更深的地幔结构有关。不同的纪律对我们对地球陆地陆地的动力学的理解做出了不同的贡献。特别是，将地球化学和地震学异质性在全球范围内的分布涉及到这两种方法中采样不同的波长：局部，用于地球化学，长波长，用于地震学。最近，这两个领域都取得了进展，在全球地震层析成像中的分辨率达到了1000公里的量表，并沿着海脊中的山脊进行了更完整的地球化学采样，从而可以调查与地震成像相称的波长的模式。同时，在开发3D中地幔循环的现实地球动力学建模方法方面取得了进展，并结合了地震学和表面可观察物的约束（例如，板块运动，地形和地质）。将这些元素捆绑在一起以更好地限制脊在山脊上采样的材料的流史正在变得可行。拟议的工作将生成新的地球化学数据集，层压模型以及地球动力模型的结果，这些模型将分发给更广泛的地球科学社区，以进一步分析，并以一种允许身临其境的3D可视化的格式分发。该奖项反映了NSF的法定任务，并认为通过基金会的知识优点和广泛的criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia crricia cripicia crricia cripicia recsectia均值得通过评估。