Collaborative Research: Thin Crust Over The Marion Rise: Remelting The Gondwanan Mantle II

合作研究：马里恩隆起的薄地壳：冈瓦纳地幔 II 的重熔

• 批准号: 1935837
• 负责人: Henry Dick
• 金额: $ 29.79万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1935837&HistoricalAwards=false
• 关键词: Collaborative; Research; Thin; Crust; Over

Earth is a dynamic planet. Its surface is being continuously created and destroyed at ocean ridges and subduction zones, which comprise the boundaries of the great tectonic plates. These processes create seismic and volcanic hazards as well as generating economic resources, thermal energy, and the planet's oceans and atmosphere. Underlying this is the circulation of the Earth's mantle, largely manifest by upwelling along ocean ridges, and mantle plumes. The latter are upward flows that produce mantle hotspots, such as Hawaii and Iceland. Where ocean ridges pass near mantle hotspots as at Iceland and the Azores Islands in the Atlantic, and at Marion Hotspot in the Indian Ocean, the ocean ridge is greatly elevated and has a chemical composition similar to the associated mantle hotspot. The standard scientific explanation for this is that the volcanic hotspot is created by a mantle plume rooted deep in the mantle, and that the flow of this plume is partially diverted to the adjacent ocean ridge, where it becomes the source of the lavas erupting there. However, there are large differences between ocean rises, and a different process may be responsible for the Marion Hotspot, a remote volcanic feature roughly 1,000 miles southeast of South Africa that sits at the boundary of the African and Antarctic tectonic plates. An international team, led by German, U.S., and Chinese scientists, is working together to test a new hypothesis that the Marion Rise represents the melting of a piece of anomalous mantle set adrift in the deep earth during the breakup of the ancient supercontinent Gondwana. The conventional deep mantle plume hypothesis predicts thickened crust all along the rise, while remelting the Gondwana mantle predicts thin or missing crust along the ridge, with isolated widely spaced local magmatic centers, with the thickest crust located at the intersection of the mantle melting anomaly with the ridge. This award supports the U.S. participation in a German-U.S.-China collaborative cruise, which is the second of a two expedition program, the first of which was led by the U.S. scientists. The U.S. Scientific Party will direct the geophysical magnetics, gravity, and multibeam mapping survey of the Southwest Indian Ridge west of the Discovery Fracture Zone north of Bouvet Island, and will use this data, in combination with the results of the rock dredging and ROV sampling on the German research vessel Sonne, to map out the extent of the mantle directly exposed on the seafloor, and constrain the crustal thickness where it is not exposed. They will characterize the differences in seafloor topography and tectonics from that seen at magmatically more robust ocean ridges such as the East Pacific Rise and Mid-Atlantic Ridge. In doing this, they will directly test and validate one of the two hypotheses for the origin of the Marion Rise described above.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.

地球是一个动态的星球。它的表面在海脊和俯冲带上不断创建和破坏，其中包括大构造板的边界。 这些过程造成了地震和火山危害，以及产生经济资源，热能以及地球的海洋和氛围。 这是地球地幔的循环，在很大程度上是通过沿着海脊和地幔羽流的向上而表现出来的。后者是产生地幔热点的向上流，例如夏威夷和冰岛。海脊通过冰岛和大西洋的亚速尔群岛以及印度洋的Marion Hotspot，海脊经过地幔热点附近的地方，海脊大大升高，具有类似于相关地幔热点的化学成分。 对此的标准科学解释是，火山热点是由扎根在地幔深处的地幔羽流创建的，并且该羽流的流动部分转移到相邻的海洋岭，在那里它成为那里爆发的熔岩的来源。 但是，海洋上升之间存在很大的差异，不同的过程可能是Marion Hotspot的原因，Marion Hotspot是南非东南约1,000英里的偏远火山，位于非洲和南极构造板块的边界。由德国，美国和中国科学家领导的一支国际团队正在共同努力，以检验一个新的假设，即马里恩崛起代表了在古老的超大型冈瓦纳（Gondwana）分手期间，在深地球上融化了一块异常的地幔套装。传统的深雨林羽假说预测沿山脊沿着山脊的薄或缺失的地壳的重新倍增，沿着山脊进行了较薄或缺失的地壳，其隔离间隔较大，位于较厚的地壳上，位于山脊的地幔融化的融化相交。 该奖项支持美国参加德国 - 中国合作巡航，这是两项探险计划的第二个，其中第一个是由美国科学家领导的。美国科学党将指导地球物理磁力学，重力和多束映射调查调查调查的西南印第安山脊在Bouvet岛以北的发现裂缝区以西的西南山脊，并将使用这些数据，并结合岩石挖泥和ROV的结果，并在德国研究容器上进行绘制的范围，以使其直接映射到cr的范围内，并在范围内绘制cr的范围。暴露。 他们将描述海底地形的差异和构造与岩浆性更强大的海脊（如东太平洋上升和中大西洋山脊）所见的差异。 在此过程中，他们将直接检验并验证上述Marion Rise的起源的两个假设之一。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估评估标准来评估值得支持的。

项目成果

Shallow recycling of lower continental crust: The Mahoney Seamount at the Southwest Indian Ridge

下大陆地壳的浅层再循环：西南印度洋脊的马奥尼海山

• DOI: 10.1016/j.epsl.2022.117968
• 发表时间: 2023
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Woelki, Dominic;Salters, Vincent;Beier, Christoph;Dick, Henry;Koepke, Juergen;Romer, Rene
• 通讯作者: Romer, Rene