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

阿根廷门多萨市和圣胡安市多次被与安第斯山脉建筑有关的地质构造引发的大震级地震破坏或夷为平地。由于活跃的地震活动发生在可以表达或隐藏在地球表面以下的断层上，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，将深部的地震活动与地球表面表达的断层和山脉联系起来。该项目将通过实地绘制断层关系图和测量记录活跃增长的安第斯山脉抬升和剥蚀历史的相关沉积盆地沉积来解决这些争论。将采用各种地质年代学和低温热年代学分析技术来确定地质结构的变形时间和大小。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。将在阿根廷科学家的帮助下，将长期断层形变的新现场记录和分析记录与地球物理观测和数十年的地震数据结合起来。这将有助于更好地了解构造力如何在深层和地表地质结构之间分配，以及哪些断层可能引发大震级地震，这些信息对于评估可能影响人类人口和基础设施的安第斯地震灾害至关重要。除了研究的科学目标外，该奖项还支持基础设施的发展，以支持不同的和历史上代表性较低的高中、本科生和博士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，并在美国西部和阿根廷的野外地区创建一次基于地点的教育虚拟实地旅行。与平板俯冲相关的构造应力已在阿根廷中西部破碎的前陆上驱动了800公里的内侧变形。在重叠的薄皮和涉及基底的构造省内进行的持续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，对于薄皮的中央Precordillera、Sierras Pampeas基底隆起或东部Precordillera构造域神秘的逆冲前缘之间的结构或运动学联系，尚无共识。首席调查人员的目标是通过以下方式解决构造之间的时间和运动学关系：(1)确定东部前纪逆冲前缘变形的时间和大小；(2)询问折返冷却和沉陷的空间模式如何与根据为该区域提出的各种构造几何和运动学基础上的预测相吻合。他们的研究计划将整合地质和构造制图、盆地分析、地质和热年代学以及弯曲热运动学模型，以区分假想的构造模型。评估阿根廷地震活跃的构造域之间的时空关系将为地下构造几何模型提供信息，缩短如何从地壳下层转移到地壳上层，以及前缘逆冲构造和前陆盆地沉积之间的长期相互作用。新的结果将量化平板俯冲过程中俯冲和俯冲板块之间增强的机械耦合的影响，这决定了造山作用的热构造演化和山带的地形生长和衰退。这一奖项反映了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。

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.