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: 2316136
• 负责人: Robert Evans
• 金额: $ 259.91万
• 依托单位: Woods Hole Oceanographic Institution
• 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=2316136&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.

俯冲带是一个板块被推到另一个板块下方的区域，是已知火山和地震灾害丰富的地区。安的列斯群岛是俯冲带火山活动的结果。当大西洋海底被推入地球时，它会下沉，并携带大量但未知量的水被释放出来，这些水要么从裂缝中被挤压，要么在地球温暖的内部升温时从矿物质中流失。释放的流体在控制地震生成和增强岩浆生成过程中发挥着作用，形成的岩浆向上移动并为形成岛屿的火山提供水源。该项目将使用电磁方法对安的列斯俯冲系统进行成像。这些数据将用于识别在安的列斯群岛下俯冲的海洋板块中的高流体含量区域，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。波多黎各大学的学生将参加实地项目。安的列斯群岛被视为一个端元系统，在缓慢扩张的大西洋中脊处形成了洋壳俯冲作用，预计将携带大量水束缚在蛇纹石化的上地幔中。传入板块的地震成像显示出高度的结构变异性，这表明进入地幔楔的高通量流体将是局部的。该项目将把这些高流体通量的局部区域与供给火山弧的熔体的产生联系起来。电磁 (EM) 方法非常适合表征流体进入俯冲系统的输送以及这些流体随后释放到上覆滑脱和地幔楔中的情况。电磁方法大致分为两类： 被动大地电磁 (MT) 方法，它使用自然发生的信号来探测很深的深度（可达 200 公里或以上）；受控源电磁（CSEM）测深，其中发射器被拖在船后并生成人工电磁信号，该信号由一系列海底仪器记录。 CSEM 对于量化地壳和上地幔中的流体非常有用。该项目将进行安的列斯群岛俯冲系统的 MT/CSEM 调查，该调查将检验以下假设：传入板块中储存的较高流体含量会导致大量水通量进入下行板片上方的前弧地壳和弧地幔楔。沿走向的流体输入的变化将表现为地幔电导率的变化，由于释放的流体量更大和生成的含水熔体，高通量区域的电导率明显更高。该实地计划将包括两次研究巡航和土地征用。该项目得到了海洋科学部的海洋地质和地球物理学计划以及地球科学部的地球物理学计划的支持。该奖项反映了 NSF 的法定使命，并已通过使用基金会的智力优点和更广泛的影响审查标准进行评估，认为值得支持。