Collaborative Research: Quantifying the thermal effects of fluid circulation in oceanic crust on temperatures in the southern Mexico subduction zone

合作研究：量化洋壳流体循环对墨西哥南部俯冲带温度的热效应

• 批准号: 2234705
• 负责人: Glenn Spinelli
• 金额: $ 40.81万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-15 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2234705&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; thermal; effects

Subduction zones are where one tectonic plate moves under another. They generate the largest earthquakes and tsunamis. Earthquake size is affected by temperatures on a fault. In subduction zones, temperatures also affect magma generation. To understand earthquake and volcano hazards in subduction zones, accurate temperature estimates are needed. Seawater flowing within subducting tectonic plates can affect temperatures. For the hazardous subduction zone of southern Mexico, the effects of this fluid flow are unknown. This causes large uncertainty in temperature estimates. This study will measure temperature in seafloor sediments and map sediment distribution off Mexico. The goals are to improve estimates of subduction zone temperatures and understand their controls. This study will benefit society by informing hazard estimates. Additionally, the project will enhance education at two Hispanic-serving institutions. Students at New Mexico Tech and the University of New Mexico will participate in the study. They will work with a researcher and student from an Earth science research center in Mexico.Accurate estimates of subduction zone temperatures are required to understand a variety of critical processes, including controls on seismogenic and aseismic behavior on subduction megathrusts. The region of flat-slab subduction in Mexico has been a focus of seismic and geodetic studies because it hosts an interesting range of behaviors on the plate interface (e.g., tremor, slow slip, presence of an ultra-slow layer postulated to be generated by fluid overpressure). Attempting to better understand physical conditions within the subduction zone, various studies predict temperatures and the distribution of slab alteration in this system. However, thermal models for the margin remain largely unconstrained due to insufficient heat flux observations on the incoming plate. Specifically, the potential presence and effects of fluid circulation in the basaltic basement aquifer of crust entering the southern Mexico subduction zone are unknown. The subduction zone in southern Mexico is among the warmest globally and the extent to which fluid circulation redistributes heat has profound implications for temperature distributions and subduction processes. This observational and modeling study will assess the thermal regime of the Cocos plate entering the subduction zone offshore southern Mexico by collecting ~650 km of seismic reflection profiles and ~200 heat flux measurements. This will provide a process-based understanding of the thermal structure of the incoming Cocos plate. The central hypotheses are: 1) hydrothermal circulation advects substantial quantities of heat in oceanic crust near the deformation front offshore southern Mexico, and 2) bending-related normal faults play an important role in hydrothermal circulation and the thermal structure of the incoming plate in this system. Analyzing and interpreting the controls on the thermal state of the Cocos plate near the deformation front will allow for the development of improved predictive models of subduction zone temperatures.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移动到另一个构造板块下方的地方。它们引发最大的地震和海啸。地震规模受断层温度的影响。在俯冲带，温度也会影响岩浆的产生。为了了解俯冲带的地震和火山灾害，需要准确的温度估计。俯冲构造板块内流动的海水会影响温度。对于墨西哥南部的危险俯冲带，这种流体流动的影响尚不清楚。这导致温度估计存在很大的不确定性。这项研究将测量海底沉积物的温度并绘制墨西哥附近沉积物的分布图。目标是改进对俯冲带温度的估计并了解其控制。这项研究将通过提供危害估计来造福社会。此外，该项目还将加强两个西班牙裔服务机构的教育。新墨西哥理工学院和新墨西哥大学的学生将参加这项研究。他们将与墨西哥地球科学研究中心的一名研究人员和学生合作。需要准确估计俯冲带温度以了解各种关键过程，包括控制俯冲巨型逆冲断层的发震和抗震行为。墨西哥的平板俯冲区域一直是地震和大地测量研究的焦点，因为它在板块界面上具有一系列有趣的行为（例如，震颤、慢滑移、假定由地震产生的超慢层的存在）流体超压）。为了更好地了解俯冲带内的物理条件，各种研究预测了该系统中的温度和板片蚀变的分布。然而，由于对传入板的热通量观测不足，边缘的热模型在很大程度上仍然不受约束。具体而言，进入墨西哥南部俯冲带的地壳玄武岩基底含水层中流体循环的潜在存在和影响尚不清楚。墨西哥南部的俯冲带是全球最温暖的俯冲带之一，流体循环重新分配热量的程度对温度分布和俯冲过程具有深远的影响。这项观测和建模研究将通过收集约 650 公里的地震反射剖面和约 200 个热通量测量值来评估进入墨西哥南部近海俯冲带的科科斯板块的热状况。这将为传入 Cocos 板的热结构提供基于流程的理解。中心假设是：1）热液循环在墨西哥南部近海变形前缘附近的洋壳中平流输送大量热量，2）与弯曲相关的正断层在热液循环和传入板块的热结构中发挥着重要作用。系统。分析和解释对变形前沿附近科科斯板块热状态的控制将有助于开发改进的俯冲带温度预测模型。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识进行评估，被认为值得支持。优点和更广泛的影响审查标准。