Collaborative Research: Utilizing Cooling Histories to Determine the Sequence and Rates of Thrusting

合作研究：利用冷却历史来确定推进的顺序和速率

• 批准号: 1524277
• 负责人: Nadine McQuarrie
• 金额: $ 27.81万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524277&HistoricalAwards=false
• 关键词: Collaborative; Research; Utilizing; Cooling; Histories

This proposal is aimed at understanding the structural, tectonic, and exhumation of a part of the Himalayan orogen in central and western Nepal. The principal investigators are investigating how fault magnitude, geometry and rate are related to uplift and exhumation in convergent margin plate tectonic systems where two continents are colliding. This research will allow the principal investigators to constrain both magnitude and age of faulting and gain insight into the geometry of these faults along a fundamental plate boundary between India and Asia in the Nepalese Himalaya, which will provide fundamental insights into how convergent plate margins evolve through time. This region is the site of large, destructive earthquakes that are a function of both geometry of the faults and the rates at which these faults move; thus, the research has the potential to further understanding in a region of active seismicity. This proposal combines thermochronometry (the age at which minerals cool) with numerical modeling to determine fault magnitude, geometry and rate. Geologic mapping and associated cross sections provide an estimate of fault geometry. This geometry provides a testable path along which rocks were displaced and cooled from the subsurface to the Earth's surface. The principal investigators will test the hypothesis that the geometry of faults controls the first-order pattern of cooling ages that are recorded in rocks, which can then be tested by comparing measured cooling ages to modeled cooling ages using different fault geometries. This approach will provide workflows, methodologies, and examples of how fault geometries, as determined from geologic cross sections, and rates impact predicted cooling ages. In addition to the scientific objectives of the study, the project is contributing to the national well-being and other socially relevant outcomes by providing for training of graduate and undergraduate students in an important STEM discipline, as well a contributing to the broadening of underrepresented groups in the earth sciences. The project it is contributing to the development of research infrastructure at two U.S. university systems, and is promoting international collaboration between U.S., German, and Nepalese scientists. Results from this research will be incorporated into classroom curricula. As part of this project, the principal investigators are developing a series of research and teaching modules that will provide interested graduate students and researchers from other institutions the skills needed to use this research approach for their own field areas and datasets, and allow educators to assign advanced undergraduates and graduate students assignments that teach the systematics of how compressional fault systems form and the relationships between deformation, erosion and deposition. The results of the research will be disseminated through peer-reviewed scientific publications literature and by presentations at professional society meetings; data obtained from the project will be archived in appropriate community supported data repositories. Combining thermochronometry with numerical modeling has an enormous potential to quantify the rates, magnitudes, and timing of deformation and erosion in active, contractional plate tectonic settings. However, the interpretations of thermochronometric data are critically dependent on determining the correct thermal, kinematic, and erosion models. Understanding how fault magnitude, geometry and rate are related to exhumation in compressional systems requires quantitatively linking the geometry and magnitude of fault slip to the distribution and amount of erosion. In this project, the principal investigators suggest that the geometry of fold-thrust belts is best delineated through balanced geologic cross-sections, and they hypothesize that the geometry of a fold-thrust belt, particularly the location and magnitude of ramps in the decollement, control the first-order pattern of cooling ages. To address this hypothesis they will apply a 2 dimensional thermo-kinematic and erosion model to forward modeled balanced cross sections to quantify the cooling history in a thrust belt setting. Balanced cross-sections provide the kinematic sequence of rocks and structures necessary to reproduce the mapped surface geology. The principal investigators will test the validity of this kinematic sequence by assigning ages over which displacement occurs, and use the range of potential velocity vectors to calculate heat transport, erosion, and rock cooling. Matching the measured cooling histories recorded by a suite of thermochronometers to that predicted by the kinematics of a balanced cross-section is an additional support for the validation of the cross section. This work will examine proposed structural geometries, the cooling ages of rocks and their interdependence in central Nepal and far western Nepal. In central Nepal, there is an abundance of geochronologic/thermochronologic data and recent maps and cross section interpretations. In far western Nepal, there are detailed maps and cross section interpretations with a growing body of geochronologic/thermochronologic data. The researchers will capitalize on these established and growing datasets to test our hypothesis by 1) evaluating a range of permissible geometries for balanced-sections (both prior to and following field work), 2) collecting critical field observations (bedding, foliation, cleavage) and necessary thermochronologic samples, 3) establishing the cooling history of duplexes and thrust sheets via a suite of thermochronometers, and 4) modeling the dependence of chronometers on structural geometries, displacement paths and rates. The intellectual merit of this project involves investigating the sensitivity and utility of thermochronometer and kinematic data for calculating the age and rate of thrust motion and associated exhumation. Using this approach in Nepal, the principal investigators can evaluate the range of shortening rates in space and time and determine if long-term shortening rates though the Himalaya are constant or variable. These methods/processes will be transportable to other contractional systems worldwide and will lead to a reevaluation of the kinematics, geometry and rates in orogenic systems.

该建议旨在理解尼泊尔中部和西部喜马拉雅造山机的一部分的结构，构造和挖掘。主要研究人员正在研究断层幅度，几何形状和速率如何与聚合边缘板构造系统中的隆起和挖掘有关，在这些系统中，两个大洲正在碰撞。这项研究将使主要研究人员能够限制断层的大小和年龄，并洞悉这些断层在尼泊尔喜马拉雅山的基本板块边界沿着基本板块边界的几何形状，这将提供有关融合板余量如何演变的基本见解。 该区域是大型，破坏性地震的地点，是断层几何形状和这些断层移动速率的函数。因此，该研究有可能在主动地震行业中进一步理解。该提案结合了热化学计（矿物质冷却的年龄）与数值建模，以确定故障幅度，几何形状和速率。地质映射和相关的横截面提供了故障几何形状的估计。 该几何形状提供了一条可测试的路径，沿着岩石被移动并从地下到地球表面冷却。主要研究人员将检验以下假设：断层的几何形状控制记录在岩石中的冷却年龄的一阶模式，然后可以通过将测量的冷却年龄与使用不同故障几何形状的建模冷却年龄进行比较来测试。这种方法将提供工作流程，方法和示例，说明是根据地质横截面确定的断层几何形状以及速率影响预测的冷却年龄的。 除了研究的科学目标外，该项目还通过为重要的STEM学科培训研究生和本科生的培训，为国家福祉和其他与社会相关的成果做出贡献，这是为地球科学中代表性不足的群体扩大的促进。该项目正在为美国两个大学系统的研究基础设施的发展做出贡献，并促进了美国，德国和尼泊尔科学家之间的国际合作。这项研究的结果将纳入课堂课程。作为该项目的一部分，首席研究人员正在开发一系列的研究和教学模块，这些模块将为其他机构提供感兴趣的研究生和研究人员，这些技能为自己的现场领域和数据集使用这种研究方法所需的技能，并允许教育工作者分配高级本科生和研究生任务，以教授对压缩缺陷系统形式形式和关系的系统学教学和deformation和Deposition和Deposition和Deposition和Deposition和Deposition之间的关系学的系统。该研究的结果将通过经过同行评审的科学出版物文献和专业社会会议的演讲来传播；从项目获得的数据将在适当的社区支持的数据存储库中存档。将热相位学与数值建模相结合具有量化活性，收缩板构造设置中变形和侵蚀的速率，大小和时机的巨大潜力。但是，热力学数据的解释主要取决于确定正确的热，运动学和侵蚀模型。了解压缩系统中的故障幅度，几何形状和速率与挖掘有关，需要定量将故障滑移的几何形状和幅度与侵蚀的分布和数量联系起来。在这个项目中，主要研究人员建议最好通过平衡的地质横截面来划定褶皱带的几何形状，并假设他们假设折叠皮带的几何形状，尤其是在分解层中坡道的位置和大小，控制着冷却年龄的第一阶模式。为了解决这一假设，他们将应用2维热基因和侵蚀模型来向前建模平衡的横截面，以量化推力带设置中的冷却历史记录。平衡的横截面提供了重现映射表面地质所需的岩石和结构的运动学序列。主要研究人员将通过分配位移的年龄来测试该运动学序列的有效性，并使用潜在速度向量的范围来计算热传输，侵蚀和岩石冷却。与平衡横截面的运动学相匹配的套件相匹配的冷却历史与横截面验证的额外支持。这项工作将检查提出的结构几何形状，岩石的冷却年龄及其在尼泊尔中部和尼泊尔西部的相互依存关系。在尼泊尔中部，有大量的地质/热量数据学数据以及最近的地图和横截面解释。在北部尼泊尔西部，有详细的地图和横截面解释，并具有越来越多的年代学/热量数据学数据。研究人员将利用这些已建立和不断增长的数据集，通过1）评估平衡部门的一系列允许的几何形状（无论是在现场工作之前还是在实地工作之前和之后），2）2）收集关键的现场观察（床上用品，叶片，叶片，裂解，裂解）和必要的热力学样本，3），建立4号供您的热量史，3），以供应和刺激素质的速度和刺激量。建模时间表对结构几何形状，位移路径和速率的依赖性。该项目的智力优点涉及研究热化学计和运动学数据的敏感性和效用，以计算推力运动的年龄和速率和相关挖掘。在尼泊尔使用这种方法，首席研究人员可以评估时空缩短率的范围，并确定喜马拉雅山脉的长期缩短率是恒定还是可变的。这些方法/过程将可以运输到全球其他收缩系统，并将导致对造山机系统中的运动学，几何形状和速率的重新评估。