Reconciling extrusion tectonics, rifting, and lithosphere-asthenosphere coupling models for the Central Highlands diffuse igneous province, Vietnam

板块构造的范式代表了地球上最基本的行星过程，是理解地球科学的核心，但关键问题仍然是许多地区如何适应构造板块的运动和应力。构造板块和下伏地幔之间的关系也仍然存在争议，而这些关系对于充分理解地球上实际驱动板块运动的因素是必要的。像印度支那这样的地区特别复杂，受到许多相互竞争的构造和地幔驱动力的影响，因此是更好地了解我们的星球如何作为一个动态的构造系统发挥作用的重要实验室。这项研究调查了越南中部高地最近火山活动和断层的起源。这项研究的目的是更好地了解印度支那的地质背景，特别是什么构造和地幔作用驱动了断裂和火山活动。这项工作有益于社会，因为它通过研究有关地球和塑造地球的过程的基本科学问题，直接促进科学进步。这项研究通过为两名职业生涯早期的女科学家提供支持，有助于扩大科学、技术、工程和数学(STEM)中代表性不足群体的参与。该项目支持STEM研究生和本科生的教育和培训，从而有助于发展一支多元化的、具有全球竞争力的劳动力队伍。该项目将有助于提高公众识字率和公众参与STEM，支持与内布拉斯加州大学州立博物馆的外联活动，以传播科学研究和教育当地社区，并通过一份书面报告，详细说明与最近火山喷发时间和新发现的断层有关的潜在危险的任何新发现。该项目促进了几所美国大学之间的合作，以及美国和越南科学家之间的国际合作。具体地说，该项目旨在测试、开发和完善一个强大的、全面的区域模型，该模型解释印度支那断裂和火山活动的动力学起源，从而通过构造地质学和火成岩地球化学的结合方法，增加对复杂体制下的构造和地幔动力学的理解。该项目的基本原理是促进对板块边界和微板块动力学以及岩石圈-软流圈耦合效应的科学理解。该项目的中心假设认为，构造挤压和软流圈流动与上升流的耦合驱动了南印度支那微板块的旋转，包括走滑和正断层的传播，并在没有地幔热柱参与的情况下产生了大量的地壳岩浆活动。拟议研究的具体研究目标是：1)评估越南中央高地断裂活动和火山活动之间的年龄关系；2)收集数据以确定中央高地的应力场，并评估其是否符合挤压或伸展主导的构造制度；以及3)通过确定随时间和地理分布喷发的熔岩的地幔来源(岩石圈与软流圈)，评估同一区域地幔上涌的证据。这些目标将通过现场绘制断层方向和运动学地图；火山喷发的同位素测年；玄武岩和地幔包体中比较的常量元素、微量元素和放射性同位素测量来实现。这项研究有望引发对火山活动和断层活动之间关系的彻底评估，构造应力驱动断层活动的起源，以及随着时间的推移识别当地岩浆来源，导致印度支那的协调构造模型。这一奖项反映了NSF的法定使命，并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，被认为值得支持。

The paradigm of plate tectonics represents the most fundamental planetary process on Earth and is central to understanding geoscience, but key questions remain about how motion of and stresses in tectonic plates are accommodated in many regions. Relationships between tectonic plates and the underlying mantle layer also remain debated, and those relationships are necessary to fully understand what actually drives plate motion on Earth. Locations like Indochina are particularly complex, influenced by a number of competing tectonic and mantle driving forces, and are thus important laboratories for better understanding how our planet functions as a dynamic, tectonic system. This study investigates the origins of recent volcanic activity and faulting in the Central Highlands of Vietnam. The goal of this research is to better understand the geologic setting of Indochina, particularly what tectonic and mantle processes drive faulting and volcanic activity. This work benefits society because it directly promotes scientific progress by investigating fundamental scientific questions about the planet and processes that shape it. The study contributes to broadening participation of underrepresented groups in science, technology, engineering and mathematics (STEM) by providing support for two early career women scientists. The project supports STEM education and training of graduate and undergraduate students, thus contributing to the development of a diverse, globally competitive workforce. The project will contribute to increased public literacy and public engagement with STEM supporting outreach events with the University of Nebraska State Museum to disseminate scientific research and educate the local community, and through a written report detailing any new findings regarding potential hazards associated with recent volcanic eruption timing and newly discovered faults. The project facilitates collaboration between several U.S. universities, as well as international collaboration between U.S. and Vietnamese scientists. In detail, this project aims to test, develop, and refine a robust, comprehensive regional model that explains the dynamic origins of faulting and volcanism in Indochina, thereby increasing understanding of tectonics and mantle dynamics in complex regimes through the combined approaches of structural geology and igneous geochemistry. The project rationale is the advancement of scientific understanding of plate boundary and microplate dynamics and lithosphere-asthenosphere coupling effects. The central hypothesis for this project states that tectonic extrusion and coupled asthenospheric flow and upwelling have driven rotation of the Southern Indochina microplate, including propagation of strike-slip and normal faulting, and produced voluminous crustal magmatism without mantle plume involvement. The specific research goals for the proposed study are: 1) to evaluate age relationships between fault movement and volcanic activity in the Central Highlands of Vietnam, 2) to gather data to define the stress field of the Central Highlands and assess whether it is consistent with an extrusion- or extension-dominated tectonic regime, and 3) to assess the evidence for mantle upwelling in the same region by identifying mantle source origins (lithosphere vs. asthenosphere) for lavas erupted over time and with geographic distribution. These objectives will be achieved through field mapping of fault orientations and kinematics; isotope dating of volcanic eruptions; and comparative major element, trace element, and radiogenic isotope measurements in basalts and mantle xenoliths. The research is expected to trigger a thorough assessment of relationships between volcanism and faulting, the origin of the tectonic stress driving faulting, and identification of local magma sources over time, leading to a reconciled tectonic model for Indochina.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.