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

俯冲带是一个板块在另一个板块下方移动的地方。它们会产生最大的地震和海啸。地震的大小受断层温度的影响。在俯冲带，温度也影响岩浆的生成。为了了解俯冲带的地震和火山灾害，需要准确的温度估计。在俯冲构造板块内流动的海水会影响温度。对于墨西哥南部危险的俯冲带来说，这种流体流动的影响是未知的。这给气温估计带来了很大的不确定性。这项研究将测量海底沉积物的温度，并绘制墨西哥近海沉积物的分布图。其目标是改善对俯冲带温度的估计，并了解它们的控制。这项研究将为社会提供危险估计信息，从而使社会受益。此外，该项目还将加强两所为拉美裔服务的机构的教育。新墨西哥理工学院和新墨西哥大学的学生将参与这项研究。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，包括对俯冲巨型逆冲的孕震和抗震行为的控制。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有一系列有趣的行为(例如，震动、慢滑、存在假定由流体超压产生的超慢层)。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岩蚀变的分布。然而，由于进入板块的热通量观测不足，边缘的热模型在很大程度上仍然不受限制。具体地说，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热的地区之一，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~650公里的地震反射剖面和~200个热通量测量来评估进入墨西哥南部俯冲带的科科斯板块的热状况。这将提供对进料Cocos板的热结构的基于工艺的了解。中心假设是：1)水热环流在墨西哥南部近海变形前锋附近的洋壳中平流大量的热量；2)与弯曲有关的正断层对该系统中的水热循环和来水板块的热结构起着重要作用。分析和解释变形前沿附近Cocos板块的热状态控制将允许开发改进的俯冲区温度预测模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.