Collaborative Research: Understanding the Processes and Timescales of Basalt Petrogenesis and Oceanic Crustal Construction at Slow-Spreading Mid-Ocean Ridges

合作研究：了解缓慢扩张的大洋中脊玄武岩成岩和洋壳构造的过程和时间尺度

• 批准号: 2317705
• 负责人: Richard Aster
• 金额: $ 3.71万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317705&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Processes; Timescales

Mid-ocean ridges represent regions of the planet where volcanic activity is generating fresh oceanic crust and submarine mountain chains as two tectonic plates spread apart. This project will measure the chemical characteristics of volcanic rock produced along the planet’s largest extent of mid-ocean ridge, known as the Mid-Atlantic Ridge. The measurements will be used to understand which components of the mantle are melting and whether volcanic activity happens continuously or in pulses. This research will aid in understanding the larger evolution of the planet, as mid-ocean ridges serve as the dominant source of new crust on the Earth. Seventy-five percent of the Earth’s magmatic activity occurs at mid-ocean ridges. This work will also help to develop an interactive exhibit at the University of Wyoming’s Geological Museum titled “Earth’s Oceans: Now and in the Past”. This exhibit will help to inform the public, from preschoolers to senior citizens, of the importance of mid-ocean ridges in the formation and continuous resurfacing of the Earth. Mid-ocean ridges offer an opportunity to understand the isotopic and lithological composition and evolution of the Earth’s mantle, the subsurface melt processes which generate basaltic magmas, and the eruptive styles and frequency which give rise to fresh oceanic crust. While the melt processes and timescales of crustal construction are well-constrained at fast-spreading mid-ocean ridges such as the East Pacific Rise, slow-spreading ridges such as the Mid-Atlantic Ridge remain comparatively understudied. Furthermore, the Mid-Atlantic Ridge has been shown to erupt isotopically and geochemically enriched lavas, reflecting potentially lithologically heterogenous mantle source domains in the sub-ridge melting regime and potential nearby influences from upwelling mantle plumes. This research will constrain the mantle components which give rise to isotopically diverse oceanic crust along the 45°N segment of the Mid-Atlantic Ridge, the melting processes by which basaltic lavas are generated and transported to the surface, and the timescales of oceanic crustal construction that result in axial volcanic ridges. To achieve this, researchers will measure major and trace element abundances, radiogenic isotopic compositions, and U-decay series nuclides from a suite of basalt samples collected from the 45°N segment of the Mid-Atlantic Ridge. In addition, tomographic imaging from beneath MAR will be constructed and coupled with the chemical and isotopic interpretations. This multi-disciplinary data set will enhance the understanding of the mantle lithologies which melt beneath the slow-spreading Mid-Atlantic Ridge, the timescales and processes of how these melts are segregated, aggregated, and transported to the surface, and the temporal progression of fresh oceanic crustal construction along slow-spreading ridge segments. This work will help to provide the scientific community with a more complete, global understanding of the nature of the Earth’s mantle and how oceanic crust is constructed. This grant will also enhance the general public’s understanding of the Earth’s Mid-Ocean ridges by creating an exhibit at the University of Wyoming’s Geological Museum titled- “Earth’s Oceans: Now and in the Past”.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.

海洋中部山脊代表了地球的区域，随着两个构造板分开，火山活动正在产生新鲜的海洋壳和海底山脉。该项目将衡量地球中部山脊最大的火山岩的化学特性，即中大西洋山脊。测量结果将用于了解地幔的哪些组成部分正在熔化，以及火山活动是否连续或脉冲发生。这项研究将有助于理解地球的更大演变，因为中山脊是地球上新地壳的主要来源。地球岩浆活动中有75％发生在海洋中部山脊。这项工作还将有助于在怀俄明大学地质博物馆的题为“地球海洋：现在和过去”的地质博物馆开发互动展览。该展览将有助于向公众通报从学龄前儿童到老年人的公众，即中山脊在地球的形成和持续重新铺面上的重要性。中山脊提供了一个机会，可以理解地球地幔的同位素和岩性组成和演变，产生基本岩浆的地下熔体过程以及产生新鲜海洋壳的喷发样式和频率。尽管在诸如东太平洋上升的快速山山脊（例如中大西洋山脊）等快速蔓延的中山山脊上，地壳结构的熔体过程和时间表受到了良好的约束。此外，大西洋中部山脊已被证明会在同位素和地球化学上富集的熔岩上爆发，反映了子河流熔化方案中潜在的岩性异源地幔源结构域，并从上升的地幔羽毛中产生了附近的影响。这项研究将限制沿中大西洋山脊的45°N段引起同位素潜水的海壳，从而产生并运输到表面的熔融过程，以及导致轴向火山脊的海洋壳结构的时间尺度。为了实现这一目标，研究人员将测量从中大西洋脊的45°N段收集的一组玄武岩样品中的主要和痕量元素丰度，放射性同位素组成和U-DECAY系列核素。此外，将构建来自MAR下方的层析成像，并与化学和同位素解释结合。这个多学科的数据集将增强对延伸的地幔岩石学的理解，这些地幔岩石融化了慢速的中大西洋山脊，这些熔体如何隔离，聚集，汇总并运输到表面的时间表和过程，以及沿慢速大洋构造沿慢慢地沿着Ridge ridge segments Segments Segments沿着慢速大洋构造的进展。这项工作将有助于为科学界提供对地球地幔本质以及海洋壳的建造方式的更完整，全球的理解。这笔赠款还将通过在怀俄明大学地质博物馆创建一个名为“地球的海洋：现在和过去的地质博物馆”的展览，从而增强公众对地球中部山脊的理解。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准通过评估来诚实地表示支持。