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: 2234706
• 负责人: Lindsay Worthington
• 金额: $ 33.92万
• 依托单位: University of New Mexico
• 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=2234706&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之下的地方。它们产生最大的地震和海啸。地震的规模受断层温度的影响。在俯冲带，温度也会影响岩浆的生成。为了了解俯冲带的地震和火山危险，需要精确的温度估计。在俯冲构造板块内流动的海水可以影响温度。对于墨西哥南部的危险俯冲带，这种流体流动的影响是未知的。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，并绘制墨西哥近海的沉积物分布图。其目标是改善俯冲带温度的估计，并了解其控制。这项研究将通过提供危害评估信息而造福社会。此外，该项目将加强两个西班牙裔服务机构的教育。新墨西哥州理工学院和新墨西哥州大学的学生将参与这项研究。他们将与来自墨西哥地球科学研究中心的一名研究人员和学生一起工作，需要对俯冲带温度进行准确估计，以了解各种关键过程，包括对俯冲巨型逆冲断层的地震和地震行为的控制。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、缓慢滑动、假定由流体超压产生的超慢层的存在）。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板片蚀变的温度和分布。然而，热模型的利润率仍然在很大程度上不受约束，由于不足的热通量观测传入板。具体而言，进入墨西哥南部俯冲带的玄武岩基底地壳含水层中的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地区之一，流体循环重新分配热量的程度对温度分布和俯冲过程有着深远的影响。这项观测和模拟研究将通过收集约650公里的地震反射剖面和约200个热通量测量值，评估进入墨西哥南部近海俯冲带的科科斯板块的热状况。这将提供一个基于过程的理解的热结构的传入Cocos板。核心假设是：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了大量的热量，2）与弯曲相关的正断层在热液循环和该系统中传入板块的热结构中起着重要作用。分析和解释变形前沿附近科科斯板块热状态的控制将允许改进俯冲带温度预测模型的发展。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。