EAR-PF: Mantle Convection Modeling as a Test of Pacific Absolute Plate Motion

丹尼尔伍德沃思博士已被授予美国国家科学基金会博士后奖学金进行研究和教育项目在休斯顿大学的指导下博士吴琼尼。这项研究将评价太平洋海盆岩石圈运动的模型，岩石圈是地球最外层的坚固层，包括整个地壳和上地幔。岩石圈被划分为板块--作为单个单元运动的板块。太平洋板块是这些板块中最大的一个，它位于太平洋的大部分地区之下。但由于它被海洋覆盖，重建它相对于地球其他部分的运动是具有挑战性的。已经开发了几种相互竞争的模型。伍德沃思博士将比较地幔的结构与每个板块运动模型预测的结构。区分太平洋板块运动的模型将使科学家更好地理解构造板块如何以及为什么移动。伴随的教育计划将侧重于STEM推广到西班牙裔社区，包括开发西班牙语-英语双语主动学习模块，介绍地球物理学概念。该研究将测试太平洋板块运动模型，该模型在北-西北走向的皇帝海山链和西-北走向的皇帝海山链之间形成~60°夏威夷-皇帝弯曲（HEB）之前和之后，沿着夏威夷热点的轨迹向西北方向延伸的夏威夷链。早期的太平洋绝对板块运动（APM）模型将HEB归因于板块运动相对于固定热点的变化，这与固定热点近似一致，该近似用于定义近似的绝对参考框架。然而，最近的分析认为HEB反映了热点运动的变化，而没有板块运动的大变化，这表明热点运动迅速。该项目将使用这些端元APM来驱动全地幔环流模型，使用并行前向对流代码TERRA，并将预测的地幔结构，合成大地水准面和动态地形与观测进行比较。本研究的目的是确定（1）HEB时太平洋板块运动的恒定或变化是否能更好地解释目前的观测结果，以及（2）热点和板块运动的特征时间尺度是否有足够的不同，从而可以认为热点运动相对于板块运动可以忽略不计。此外，通过研究由局部板块运动驱动的全球地幔对流模型的预测，它探索了在当地岩石圈尺度上运行的过程与地幔尺度上的过程之间的关系。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Daniel Woodworth has been awarded an NSF EAR Postdoctoral Fellowship to conduct research and education projects at the University of Houston under the mentorship of Dr. Jonny Wu. The study will evaluate models of the motion of the lithosphere, Earth’s outermost strong layer, consisting of the entire crust plus the upper mantle, in the Pacific Ocean basin. The lithosphere is divided into plates – segments that move as single units. The Pacific Plate, which underlies much of the Pacific Ocean, is the largest of these. But because it is covered by ocean, reconstructing its movement relative to the rest of Earth is challenging. Several competing models have been developed. Dr. Woodworth will compare the structure of the mantle with that predicted by each model of plate motion. Distinguishing between models of Pacific Plate motion will allow scientists to better understand how and why tectonic plates move. The accompanying educational plan will focus on STEM outreach to the Hispanic community, including developing Spanish-English bilingual active learning modules that introduce geophysical concepts.The study will test models of Pacific Plate motion before and after the formation of the ~60° Hawaiian-Emperor Bend (HEB) between the north-northwest trending Emperor Seamount Chain and the west-northwest trending Hawaiian Chain in the track of the Hawaiian Hotspot. Prominent early Pacific absolute plate motion (APM) models attributed the HEB to a change in plate motion relative to a stationary hotspot, consistent with the fixed-hotspot approximation, which had been used to define an approximate absolute reference frame. However, more recent analyses have argued that the HEB instead reflects a change in hotspot motion without a large change in plate motion, suggesting rapid hotspot motion. This project will use these endmember APMs to drive whole-mantle circulation models using the parallel forward convection code TERRA and compare the predicted mantle structures, synthetic geoids, and dynamic topography to observations. The objectives of this study are to determine (1) whether constant or changing Pacific Plate motion at the time of HEB better explains present observations and thus (2) whether the characteristic temporal scales of hotspot and plate motion are sufficiently different such that hotspot motion may be considered negligible relative to plate motion. Further, by examining the predictions of global mantle convection models driven by local plate motion it explores the relationship between processes operating at the scale of the local lithosphere and processes at the scale of the mantle.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.