Collaborative Research: Moving mountains: timing and emplacement of the Marysvale gravity slide complex

火山场是动态环境，其特点是景观迅速演变，具有极大的潜在危害。该研究项目的重点是学习和理解火山场崩塌和大型滑坡产生的过程。该项目的目标将通过对犹他州西南部的古代Marysvale重力滑坡复群进行地质测绘来实现，这是世界上最大的此类结构之一，由三个独立的超大规模滑坡组成，确定滑坡中岩石的年龄，并模拟滑坡的起始和侧向移动到其起始地点以南超过35公里的距离。这个研究项目是一个新的多机构、多学科的合作项目，将为研究生和本科生提供支持。本研究收集的高分辨率三维地质数据将用于开发虚拟实地考察和野外营地测绘模块。这些模块将是交互式的，包含露头模型、地质图和样本，使学生和公众能够更多地了解火山灾害和大规模滑坡。这些模块还将服务于一个更广泛的使命，使地球科学能够为广泛、多样化的人群所接受。晚渐新世至中新世期间，美国犹他州西南部的Marysvale火山场经历了连续三次超大规模的灾难性崩塌事件，统称为Marysvale重力滑坡复合体（MGSC）。地层演替、运动指标、基底构造、普遍碎裂和伪石质共同表明，每一次滑坡的就位都是在个别事件中以高速发生的。这些滑坡的悬而未决的问题包括：(1)火山场的条件使它容易发生大规模的崩塌；(2)导致巨大的滑坡在重力的推动下以高速移动数十公里的因素。MGSC提供了一个极好的机会来解决这些问题，由于内部结构和滑块的基底滑动面的特殊暴露。通过结合地质制图、地质年代学、岩石力学分析和数值模拟的多学科方法，我们将根据火山场的演化和主要喷发事件来评估滑动的起始时间，摩擦弱基底对滑动起始的作用，以及热压、损伤和剪切局部化对滑动移动和减速的综合作用。地质填图和野外工作，结合40Ar/39Ar和锆石U-Pb年代学，将为每次滑动的时间、规模和连续性以及基底滑动面的结构提供约束条件。岩石性质的实验室测量，结合基于现场的地质参数，将用于约束促进滑动迁移的耦合过程和滑动前稳定条件的数值模型，这代表了对大规模、长周期滑坡模型的前所未有的地质约束水平。本项目由地球科学部构造学项目和岩石与地球化学项目共同资助。该奖项反映了美国国家科学基金会的法定使命，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。

Volcanic fields are dynamic environments, characterized by rapidly evolving landscapes and extreme hazard potential. This research project is focused on learning and understanding the processes involved in collapse of volcanic fields and production of mega-scale landslides. The project objectives will be achieved by geologic mapping of the ancient Marysvale gravity slide complex in southwestern Utah, one of the largest such structures in the world that is made up of three individual mega-scale slides, determining the age of rocks contained in the slides, and modeling slide initiation and lateral transport to distances over 35 km to the south of their initiation sites. This research project assembles a new multi-institution, multi-disciplinary collaboration and will provide support for graduate and undergraduate students. High-resolution 3D geologic data collected during this study will be used to develop virtual field trips and field camp mapping modules. These modules will be interactive and contain outcrop models, geologic maps, and samples that will enable students and the public to learn more about volcanic hazards and mega-scale landslides. The modules will also serve a broader mission to make the Earth Sciences accessible to a broad, diverse population. During the late Oligocene to Miocene, the Marysvale volcanic field of southwestern Utah, USA, experienced three consecutive mega-scale catastrophic collapse events, collectively called the Marysvale gravity slide complex (MGSC). The stratigraphic succession, kinematic indicators, basal structures, pervasive fragmentation, and pseudotachylyte collectively suggest that emplacement of each of these slides occurred at high velocity during individual events. Outstanding questions for these landslides include (1) the conditions of the volcanic field that made it susceptible to mega-scale collapse, and (2) the factors which allowed the resulting gigantic slides to travel tens of kilometers at high velocity, driven by gravity. The MGSC provides an excellent opportunity to address these questions due to the exceptional exposure of the internal structure and basal slide planes of the slide blocks. Through a multidisciplinary approach combining geologic mapping, geochronology, rock mechanics analyses, and numerical modeling, we will evaluate the timing of slide initiation with respect to evolution of the volcanic field and major eruptive events, the role of a frictionally weak substrate on slide initiation, and the combined roles of thermal pressurization, damage, and shear localization on slide mobility and deceleration. Geological mapping and field work, combined with 40Ar/39Ar and zircon U-Pb geochronology, will provide constraints on timing, the dimensions and continuity of each slide, and the structure of the basal sliding surface. Laboratory measurements of rock properties, combined with field-based geologic parameters, will be used to constrain numerical models of both the coupled processes facilitating slide mobility and the conditions of pre-slide stability, representing an unprecedented level of geologic constraint on models of massive-scale, long runout landslides.This project is jointly funded by the Tectonics program and the Petrology & Geochemistry 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.