Collaborative Research: US-EAGLE \(Ethiopia-Afar Grand Lithospheric Experiment\): Modification of Lithospheric Structure During Continental Breakup

合作研究：US-EAGLE（埃塞俄比亚-阿法尔大岩石圈实验）：大陆破裂期间岩石圈结构的改变

• 批准号: 0208592
• 负责人: Kevin Mickus
• 金额: --
• 依托单位: Missouri State University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208592&HistoricalAwards=false
• 关键词: Collaborative; Research; US; EAGLE; Ethiopia

0208592MickusThe architecture of continental margins in terms of how they are created is not well understood because most of the previous work has been on successfully rifted margins after rifting is complete. Both continental (fault dominated) end-members and oceanic (magma dominated) rift end-members are well studied, but the transitional stage is not understood. This project will document this critical transition from continental to oceanic rifting. The PIs will carry out seismic experiments, integrated with geochemical, gravity and structural studies, to study lithospheric structure in one of the rare areas where the transition from continental rifting to incipient spreading is captured - the main Ethiopian Rift (MER). In the MER the along-axis transition to initial seafloor spreading provides a spatial proxy for temporal variability. Specific objectives are: 1) to determine detailed crust and mantle structure across and along a transitional rift segment and 2) to understand magmagenesis beneath and within the rift. The PIs will obtain crustal P-and S-velocity cross-sections that can be interpreted for lithology across the Ethiopian rift at 10 deg. N where active magmatic centers first appear, and along-strike to the north to study the transition into fully magmatic rifting. They will interpret existing and new gravity data in light of their new seismic data, and use geochemical data to constrain the physical state of the upper mantle and magmatic inputs to the crust.The project (US - EAGLE) is fully integrated with the already funded UK - EAGLE initiative. Scientists at Leicester, Leeds and London, have been awarded UK funds to carry out a single refraction profile across the Ethiopian rift in January 2003, coupled with local seismicity studies and teleseismic recording. The US - EAGLE PIs will shoot and record a complementary orthogonal along-axis wide-angle profile; and will shoot fan shots into these linear arrays and the local seismic network to provide a measure of 3D coverage. Together, these seismological experiments form a nested, multi-scale seismic image of the Ethiopian rift and plume. The seismic studies will be coupled with geochemical and petrological and gravity studies (US), and structural, thermochronological, magnetotelluric and additional gravity studies (UK).***

0208592Mickus 大陆边缘的构造在如何创建方面还没有得到很好的理解，因为之前的大部分工作都是在裂谷完成后成功裂谷的边缘上进行的。大陆（断层主导）端元和海洋（岩浆主导）裂谷端元都得到了深入研究，但过渡阶段尚不清楚。该项目将记录从大陆裂谷到海洋裂谷的关键转变。 PI 将开展地震实验，结合地球化学、重力和结构研究，研究埃塞俄比亚主裂谷 (MER) 的岩石圈结构，该区域记录了从大陆裂谷到早期扩张的过渡过程。在 MER 中，沿轴向初始海底扩张的过渡为时间变化提供了空间代理。具体目标是：1）确定过渡裂谷段上和沿过渡裂谷段的详细地壳和地幔结构；2）了解裂谷下方和裂谷内的岩浆成因。 PI 将获得地壳 P 和 S 速度横截面，可以解释 10 度埃塞俄比亚裂谷的岩性。 N 是活跃岩浆中心首次出现的地方，并沿走向向北研究完全岩浆裂谷的过渡。他们将根据新的地震数据解释现有的和新的重力数据，并使用地球化学数据来约束上地幔的物理状态和对地壳的岩浆输入。该项目（美国 - EAGLE）与已经资助的英国 - EAGLE 计划完全整合。莱斯特、利兹和伦敦的科学家获得英国资助，于 2003 年 1 月对埃塞俄比亚裂谷进行单一折射剖面研究，并结合当地地震活动研究和远震记录。 US-EAGLE PI 将拍摄并记录互补的正交沿轴广角轮廓；并将向这些线性阵列和本地地震网络发射扇形镜头，以提供 3D 覆盖范围的测量。这些地震学实验共同形成了埃塞俄比亚裂谷和羽流的嵌套多尺度地震图像。地震研究将与地球化学、岩石学和重力研究（美国）以及结构、热年代学、大地电磁和附加重力研究（英国）相结合。***