Collaborative Research: Imaging small-scale convection and structure of the mantle in the south Pacific: a US contribution to international collaboration PacificArray

合作研究：对南太平洋小规模对流和地幔结构进行成像：美国对国际合作的贡献 PacificArray

• 批准号: 1658070
• 负责人: Donald Forsyth
• 金额: $ 17.71万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1658070&HistoricalAwards=false
• 关键词: Collaborative; Research; Imaging; small; scale

All deformation on the surface of Earth, including faulting responsible for earthquakes, is produced by the motion of tectonic plates. It is widely accepted that thermal convection in the mantle drives plate motion, but details of that convection and how exactly it moves the plates are poorly understood. Oceanic plates make up 70% of the Earth's surface and offer important windows into mantle convection, yet they are largely unexplored due to the lack of seismic data from the ocean basins. Questions abound regarding the thermal structure of oceanic plates, the significance of volcanism in the middle of oceanic plates, and how the convecting mantle beneath the plates controls their movements. Waves in the gravity field and un-explained shallowing of the ocean floors hint at small-scale convection beneath the oceanic plates. This project contributes to an international effort to strategically place temporary arrays of instruments across the Pacific Ocean basin that record the energy from earthquakes. Recent community advances in ocean bottom seismographs will be used to record unique datasets in locations where large gaps in coverage exist today. These data will allow us to infer deformation and variations in mantle temperature related to small-scale convection. As part of the international collaboration, all data will be openly available to scientists worldwide. The project supports the training of graduate and undergraduate students.This project will collect 12-15 months of broadband ocean bottom seismograph (OBS) data in two 30-station arrays in the central and southern Pacific. These arrays, deployed at two distinct plate ages (~30 Ma and ~120 Ma), will address specific critical questions on the dynamics of the oceanic asthenosphere, including its underlying state (temperature, presence of melt, water or other volatiles, and deformation mechanism). The arrays are designed to image the anisotropic velocity signature of small-scale convection, which has been invoked to explain the flattening of the age versus depth curve in old ocean plates, 140-200 km wavelength gravity lineations, and ubiquitous off-axis, non-plume volcanism observed at a variety of scales. Anisotropic surface wave and body wave tomographic models will be supplemented by shear wave splitting and attenuation measurements to obtain a multi-faceted understanding of the asthenosphere and base of the plates. Finally, the order-of-magnitude increases in path coverage for surface and body waves in the south-central Pacific will enable new advances in global tomography.

地球表面上的所有变形，包括负责地震的断层，都是由构造板的运动产生的。 人们普遍认为，地幔中的热对流驱动板运动，但是该对流的细节及其确切地移动板的细节对板的理解很少。 海洋板占地球表面的70％，并为地幔对流提供了重要的窗户，但是由于海盆内缺乏地震数据，它们在很大程度上没有探索。 关于海洋板的热结构，火山在海洋板中间的重要性以及对流板下面的对流地幔如何控制其运动的问题很多。重力场中的波浪和海底未解释的浅水暗示着海洋板下方的小规模对流。该项目有助于一项国际努力，以战略性地将临时阵列置于太平洋盆地，以记录地震中的能量。海底地震仪的最新社区进展将用于记录当今存在较大差距的位置的独特数据集。这些数据将使我们能够推断出与小规模对流有关的地幔温度的变形和变化。 作为国际合作的一部分，所有数据都将公开向全球科学家提供。该项目支持研究生和本科生的培训。该项目将在中部太平洋中部和南太平洋的两个30个站阵列中收集12-15个月的宽带海洋底部地震仪（OBS）数据。这些阵列部署在两个不同的板年龄（〜30 mA和〜120 mA）上，将解决有关海洋运动层动态的特定关键问题，包括其基本状态（温度，熔体，水或其他挥发物以及变形机制）。阵列旨在成像小尺度对流的各向异性速度特征，该阵列已被调用以解释旧海板的年龄与深度曲线的变平，140-200 km波长的重力线局部线，无处不在的距离，非斑点火山静脉曲张，在各种量表上观察到。各向异性的表面波和人体波断层扫描模型将通过剪切波分裂和衰减测量补充，以获得对小动圈和板的基础的多方面理解。最后，在中南部太平洋中的表面和人体波的路径覆盖率增加，将在全球断层扫描中取得新的进步。

项目成果

The Pacific OBS Research into Convecting Asthenosphere (ORCA) Experiment

太平洋 OBS 对流软流圈 (ORCA) 实验研究

• DOI: 10.1785/0220210173
• 发表时间: 2021
• 期刊: Seismological Research Letters
• 影响因子: 3.3
• 作者: Eilon, Zachary C.;Gaherty, James B.;Zhang, Lun;Russell, Joshua;McPeak, Sean;Phillips, Joseph;Forsyth, Donald W.;Ekström, Göran
• 通讯作者: Ekström, Göran

Sub‐Lithospheric Small‐Scale Convection Tomographically Imaged Beneath the Pacific Plate

太平洋板块下方岩石圈下小尺度对流层析成像

• DOI: 10.1029/2022gl100351
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Eilon, Zachary C.;Zhang, Lun;Gaherty, James B.;Forsyth, Donald W.;Russell, Joshua B.
• 通讯作者: Russell, Joshua B.