Collaborative Research: Resolving thin-skinned and basement-involved deformation within a seismically active broken foreland region, San Juan, Argentina

阿根廷的门多萨（Mendoza）和圣胡安（San Juan）等城市多次被与安第斯山脉构造相关的地质构造所引发的大地震破坏或夷为平地。由于活跃的地震活动发生在断层上，这些断层可以在地表上表现出来，也可以隐藏在地表之下，所以这些神秘结构的性质和历史仍然存在争议。已经提出了几个相互竞争的地质模型，将地震活动与地表的断层和山脉联系起来。该项目将通过实地考察来解决这些争论，绘制断层关系图，测量相关的沉积盆地沉积物，记录活跃的安第斯山脉的隆起和侵蚀历史。各种地质年代学和低温热年代学分析技术将被用来确定整个地质构造的变形时间和程度。结果将使用计算模型进行整合，以帮助解决这些安第斯山脉有争议的地质历史。在合作的阿根廷科学家的帮助下，长期断层变形的新的实地和分析记录将与地球物理观测和几十年的地震数据相结合。这将使人们更好地了解构造力是如何在深层和表层地质结构之间分配的，以及哪些断层可能产生大地震，这些信息对于评估安第斯地震的危害至关重要，这些地震可能影响到人口和基础设施。除了研究的科学目标之外，该奖项还支持基础设施的发展，以支持多样化和历史上代表性不足的高中、本科和博士学生参与地球科学研究和教育。这将包括指导参与机构的本科生和研究生，并通过美国西部和阿根廷的实地考察地区创建一个基于地点的教育虚拟实地考察。与平板俯冲有关的构造应力导致阿根廷中西部破碎前陆向内变形800公里。在重叠的薄皮和涉及地下室的构造省内不断缩短，使这个破碎的前陆地区成为地球上地震最活跃的地区之一。然而，对于薄皮中部Precordillera、Pampeanas山脉基底隆起或东部Precordillera构造域的神秘逆冲前缘之间的结构或运动学联系，目前还没有达成共识。主要研究人员的目标是通过(1)确定东部pre - cordillera逆冲锋面变形的时间和幅度，以及(2)询问人体冷却和下沉的空间模式如何与基于该地区各种结构几何和运动学提出的预测相吻合，来解决结构之间的时间和运动学关系。他们的研究计划将整合地质和构造测绘、盆地分析、地质和热年代学以及弯曲热运动学建模，以区分假设的构造模型。评估阿根廷地震活跃构造域之间的时空关系，将为地下构造几何模型提供信息，如何缩短从地壳低层到上层的转移，以及锋面冲断构造与前陆盆地沉积之间的长期相互作用。新的研究结果将量化平板俯冲过程中俯冲和上覆板块之间增强的力学耦合作用，从而指示造山热构造演化和山带地形的生长和衰减。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。

The cities of Mendoza and San Juan, Argentina, have been repeatedly damaged or leveled by large-magnitude earthquakes generated by geological structures associated with Andean mountain building. Because active seismicity occurs along faults that can be expressed at or hidden below Earth’s surface, the nature and history of these enigmatic structures remains debated. Several competing geologic models have been proposed that link the seismicity at depth with faults and mountain ranges expressed at Earth’s surface. This project will address these debates through fieldwork to map fault relationships and measurement of associated sedimentary basin deposits that record the uplift and erosion history of actively growing Andean ranges. A variety of geochronologic and low-temperature thermochronologic analytical techniques will be employed to determine the timing and magnitude of deformation across the geological structures. Results will be integrated using computational models to help resolve the debated geologic history for these Andean ranges. New field and analytical records of long-term fault deformation will be integrated with geophysical observations and decades of earthquake data with the help of collaborating Argentinian scientists. This will lead to a better understanding of how tectonic forces are partitioned among deep and surficial geologic structures and which faults may generate large magnitude earthquakes, information that is critical for assessments of Andean earthquake hazards with the potential to impact human populations and infrastructure. In addition to the scientific goals of the research, the award supports the development of infrastructure to support the engagement of diverse and historically underrepresented high school, undergraduate, and PhD-level students in geoscience research and education. This will involve mentoring undergraduate and graduate students at the participating institutions and creating a place-based educational virtual field trip through the western USA and field area in Argentina.Tectonic stresses associated with flat slab subduction have driven deformation 800 km inboard across the broken foreland of west-central Argentina. Ongoing shortening accommodated within the overlapping thin-skinned and basement-involved structural provinces makes this broken foreland region one of the most seismically active places on Earth. However, there is no consensus on the structural or kinematic links between the thin-skinned Central Precordillera, the Sierras Pampeanas basement uplifts, or the enigmatic thrust front of the Eastern Precordillera structural domain. The principal investigators aim to resolve the temporal and kinematic relationships among structures by (1) determining the timing and magnitude of deformation in the Eastern Precordillera thrust front and (2) interrogating how spatial patterns in exhumational cooling and subsidence coincide with predictions based on the various structural geometries and kinematics proposed for the region. Their research plan will integrate geologic and structural mapping, basin analysis, geo- and thermochronology, and flexural thermokinematic modeling to discriminate between hypothesized structural models. Evaluating spatial-temporal relationships among the seismically active, structural domains in Argentina will inform models of subsurface structural geometries, how shortening transfers from lower to upper crustal levels, and the long-term interactions between frontal thrust structures and foreland-basin sedimentation. New results will quantify the effects of enhanced mechanical coupling between the subducting and overriding plate during flat slab subduction, which dictates the thermo-tectonic evolution of orogenesis and topographic growth and decay of mountain belts.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.