Collaborative Research: The influence of incoming plate structure and fluids on arc melt generation at the Lesser Antilles subduction system

合作研究：来料板结构和流体对小安的列斯群岛俯冲系统电弧熔化产生的影响

• 批准号: 2316137
• 负责人: Samer Naif
• 金额: $ 34.82万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2316137&HistoricalAwards=false
• 关键词: Collaborative; Research; influence; incoming; plate

Subduction zones, where one tectonic plate is pushed beneath another, are known areas of abundant volcanic and seismic hazard. The Antilles islands are the result of such volcanic activity at a subduction zone. As the Atlantic seafloor is pushed down into the earth, it sinks, carrying with it a large, but unknown volume of water that is released, either squeezed from cracks, or lost from minerals as they heat up in the warmer interior of the earth. Released fluids play a role in controlling earthquake generation and enhancing the process of magma generation, with the magma formed moving upwards and feeding the volcanoes that create the islands. This project will use electromagnetic methods to image the Antilles subduction system. These data will be used to identify areas of high fluid content including both water and magma in the oceanic plate that is subducting beneath the Antilles. Broader impacts include international collaborations with Germany and France and support for early career researchers graduate students, and undergraduates. Students from the University of Puerto Rico will participate in the field programs. The Antilles is viewed as an end-member system with subduction of oceanic crust formed at the slow spreading Mid-Atlantic Ridge expected to carry large volumes of water bound within serpentinized upper-mantle. Seismic imaging of the incoming plate shows a high degree of structural variability that suggests that high fluxes of fluids into the mantle wedge will be localized. This project will link these localized areas of high fluid flux to the generation of melts that feed the volcanic arc. Electromagnetic (EM) methods are ideal for characterizing the transport of fluids into a subduction system and the subsequent release of those fluids into the overlying decollement and mantle wedge. EM methods broadly fall into two categories: the passive magnetotelluric (MT) method, which uses naturally occurring signals to look to great depth (up to 200 km or more); and controlled source electromagnetic (CSEM) sounding, in which a transmitter is towed behind a ship and generates an artificial EM signal that is recorded by an array of seafloor instruments. CSEM is useful for quantifying fluids in the crust and uppermost mantle. This project will acquire a MT/CSEM survey across the Antilles subduction system that will test the hypothesis that higher fluid contents stored in the incoming plate results in a substantial water flux into the forearc crust and arc mantle wedge above the downgoing slab. Variations in fluid input along strike will be manifested as variations in mantle conductivity, with regions of high flux being substantially more conductive as a result of the larger volume of fluids released and hydrous melts generated. The field program will consist of two research cruises and land acquisition.This project is supported by the Marine Geology and Geophysics program in the Division of Ocean Sciences and the Geophysics program in the Division of Earth Sciences.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.

俯冲带是一个构造板块被推到另一个板块之下的地方，是已知的火山和地震危险丰富的地区。安的列斯群岛就是俯冲带火山活动的结果。随着大西洋海底被推入地球，它下沉，携带着大量但未知数量的水被释放出来，要么从裂缝中挤压出来，要么从矿物中流失，因为它们在地球温暖的内部加热。释放的流体在控制地震发生和增强岩浆生成过程中发挥作用，形成的岩浆向上移动并为形成岛屿的火山提供营养。该项目将使用电磁方法对安的列斯俯冲系统进行成像。这些数据将用于确定在安的列斯群岛下俯冲的海洋板块中的高流体含量地区，包括水和岩浆。更广泛的影响包括与德国和法国的国际合作，以及对早期职业研究人员、研究生和本科生的支持。来自波多黎各大学的学生将参加实地项目。安的列斯群岛被认为是一个端元系统，在缓慢扩张的中大西洋海岭形成的洋壳俯冲，预计将携带大量的水束缚在蛇形上地幔内。传入板块的地震成像显示了高度的结构变化，这表明进入地幔楔的高通量流体将被局部化。该项目将把这些局部的高流体通量地区与供给火山弧的熔融物的产生联系起来。电磁（EM）方法是表征流体进入俯冲系统和随后释放这些流体到上覆滑脱和地幔楔的传输的理想方法。电磁法大致分为两类：被动大地电磁法，它利用自然产生的信号探测到很深的地方（最深可达200公里或更深）;可控源电磁法，它将发射器拖在船后，产生人工电磁信号，由海底仪器阵列记录。CSEM可用于定量地壳和上地幔中的流体。该项目将在安的列斯群岛俯冲系统进行MT/CSEM测量，以检验以下假设：流入板块中储存的较高流体含量导致大量水流入下行板块上方的弧前地壳和弧幔楔。流体输入沿着走向的变化将表现为地幔电导率的变化，高通量区域由于释放的流体体积较大和生成的含水熔体而具有更高的电导率。该项目由海洋科学部的海洋地质和地球物理项目以及地球科学部的地球物理项目支持。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。