Collaborative Research: Tectono-magmatic Controls on the Origin and Evolution of Mid-Ocean Ridge Segmentation at Slow-to-Intermediate Spreading Rates - Top down or bottom up

地球表面被分成一组坚硬的构造板块，这些板块随着地幔下部的对流而迁移和相互作用。大洋中脊是地球上最大的火山系统，代表着板块边界，在那里构造板块相互分离。海脊被分成离散的扩张段，由断层带分隔，这些断层带适应不同程度的走滑运动和伸展。该项目将使用最先进的3-D数值模型来量化导致这些扩张段形成的过程以及分隔它们的偏移带内的变形方式。这项研究支持的科学将支持STEM教育，使其与板块构造和地质灾害的基本理解相关联。PI将在当地的K-12学校进行演讲，并与高中教师合作创建符合物理课程中特定里程碑的演示。通过这个项目开发的计算代码将通过BitBucket公共存储库提供给任何人。最后，拥有地质学、地球物理学和高性能计算专业知识的国际研究团队将确保波士顿大学和夏威夷大学的两名研究生发展下一代地球科学家所需的跨学科技能。大洋中脊分段是板块构造的一级表现形式，但对不同形式的洋脊分段偏移量的成因尚有初步认识。认识上的差距在很大程度上是因为之前的绝大多数研究都集中在岩石圈(自上而下)或地幔/岩浆(自下而上)控制上，而不是两者兼而有之。这项研究将建立一个分段的大洋中脊的三维地球动力学模型，以探索(I)岩浆调节伸展的比例M，(Ii)分段偏移长度，以及(Iii)岩石圈厚度变化，以及(Iv)断层流变性如何决定两段之间的偏移是以局部转换断层的形式，还是以非变换偏移的更分散和可变的变形特征的区域的形式。将测试模型预测，并基于地形和断层特征的分析来精炼参数空间，包括在原型变换和非变换偏移量下的M测量。最后，这项研究将使用允许岩浆注入位置动态演化的模型来调查大洋中脊分段的起源和演化，并影响相邻的偏移量是以非转换偏移量的形式还是演化为转换断层的形式。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Earth's surface is divided into a collection of rigid tectonic plates that migrate and interact in response to convection in the underlying mantle. Mid-ocean ridges, the largest volcanic system on Earth, represent plate boundaries where tectonic plates move apart from one another. Ridges are divided into discrete spreading segments, separated by zones of faulting that accommodate varying degrees of strike-slip motion and extension. This project will use state-of-the-art 3-D numerical models to quantify the processes that lead to the formation of these spreading segments and the style of deformation within the offset zones that separate them. The science supported by this research will bolster STEM education in its relevance to a basic understanding of plate tectonics and geohazards. The PIs will give presentations in local K-12 schools and work with high school teachers to create demonstrations that meet specific milestones in physics curricula. The computational code developed through this project will be made available to anyone via the BitBucket public repository. Finally, the international research team with expertise in geology, geophysics, and high-performance computing will ensure that the two graduate students at Boston Colelge and the Univeristy of Hawaii will develop the cross-disciplinary skills needed by the next generation of Earth scientists. Mid-ocean ridge segmentation is the first-order manifestation of plate-tectonics and yet, we still have only a preliminary understanding of the causes for the different forms of segment offsets. This gap in knowledge is largely a result of the fact that the vast majority of prior studies have focused on either lithospheric (top down) or mantle/magma (bottom up) controls, but not both. This study will develop 3-D geodynamic models of a segmented mid-ocean ridge to explore how (i) the fraction of magmatically accommodated extension, M, (ii) segment offset length, and (iii) lithosphere thickness variations, and (iv) fault rheology determine whether the offset between two segments takes the form of a localized transform fault or a zone of more diffuse and variable deformation characteristic of non-transform offsets. Model predictions will be tested and the parameter space refined based on analyses of topography and fault characteristics, including measurements of M, at archetypal transforms and non-transform offsets. Finally, the study will investigate the origin and evolution of mid-ocean ridge segmentation using models that allow the location of magma injection to evolve dynamically and to influence whether adjacent offsets take the form of a non-transform offset or evolves into a transform fault.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.