Morphology, Stability and Paleointensity of the Early Geomagnetic Field as Recorded by 2.9-2.4 Ga Mafic Rocks in Western Australia

西澳大利亚 2.9-2.4 Ga 镁铁质岩石记录的早期地磁场的形态、稳定性和古强度

• 批准号: 0711453
• 负责人: Aleksey Smirnov
• 金额: --
• 依托单位: Michigan Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711453&HistoricalAwards=false
• 关键词: Morphology; Stability; Paleointensity; Early; Geomagnetic

Data on the long-term history and characteristics of geomagnetic field in the Precambrian are crucial for understanding the origin and nature of the early Earth's geodynamo and as a prerequisite for using paleomagnetism to study the geological processes of the early Earth. In the absence of strict theoretical constraints, study of the direction and strength of the geomagnetic field becomes a principal source of these data. The Archean-Proterozoic boundary interval is of special interest because it may mark the time of initial growth of the solid inner core, which may have affected the energetic and morphological characteristics of the geodynamo. The morphology, stability, and strength of the Late Archean and Early Proterozoic geodynamo are investigated by detailed paleodirectional and paleointensity analyses of three mafic magmatic suites in Western Australia, which contains the world's most pristinely preserved record of such rocks through the time interval under consideration: ~2.42 Ga Widgiemooltha dike swarm in the Yilgarn craton, ~2.78 Ga mafic lava flows and dikes of the Fortescue group of the Pilbara craton, and ~2.92 Ga layered mafic complexes of the western Pilbara craton. This study provides a synoptic view of the Late Archean-Early Proterozoic geodynamo, including time-averaged paleointensity values, estimates of the relative contributions from dipole and non-dipole field components, and paleolatitude-dependent estimates of paleosecular variation. The study generates important constraints on models of the Earth's thermal evolution and age of inner core formation. Broader impacts of this work include educational efforts at Michigan Technological University and Yale University, such as involvement of graduate and undergraduate students in all aspects of the work including both field assistance and laboratory analyses, as well as preparation of a PhD dissertation and senior research projects.

关于前寒武纪中地磁领域的长期历史和特征的数据对于理解早期地球地球地球地球的起源和性质至关重要，也是利用古磁性研究早期地球地质过程的先决条件。在没有严格的理论约束的情况下，研究地磁领域的方向和强度成为这些数据的主要来源。大将原仓的边界间隔具有特殊的兴趣，因为它可能标志着固体内核的初始生长时间，这可能影响了Geodynamo的能量和形态学特征。 The morphology, stability, and strength of the Late Archean and Early Proterozoic geodynamo are investigated by detailed paleodirectional and paleointensity analyses of three mafic magmatic suites in Western Australia, which contains the world's most pristinely preserved record of such rocks through the time interval under consideration: ~2.42 Ga Widgiemooltha dike swarm in the Yilgarn craton, ~2.78 Ga mafic皮尔巴拉·克拉顿（Pilbara Craton）Fortescue集团的熔岩流和堤防，以及〜2.92 Ga层的西部皮尔巴拉·克拉顿（Pilbara Craton）层状镁铁质综合体。这项研究提供了晚期天生古生代的地球杂质的概要视图，包括时间平均的古显着值，对偶极子和非偶极场成分的相对贡献的估计以及古分子变化的古溶于估计值。该研究对地球热演化的模型和内部核心形成的年龄产生了重要的限制。这项工作的更广泛影响包括在密歇根技术大学和耶鲁大学的教育工作，例如研究生和本科生参与工作的各个方面，包括现场援助和实验室分析，以及准备博士学位论文和高级研究项目。