Deciphering the Role of Deformation in Orogenic Evolution Through Multi-scale Structural Studies in a "Crustal Laboratory", Central Sierra Nevada, California

通过加利福尼亚州内华达山脉中部“地壳实验室”的多尺度结构研究解读变形在造山演化中的作用

• 批准号: 1524798
• 负责人: Scott Paterson
• 金额: $ 27.02万
• 依托单位: University of Southern California
• 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 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524798&HistoricalAwards=false
• 关键词: Deciphering; Role; Deformation; Orogenic; Evolution

This project focuses on a multiscale investigation aimed at understanding deformation processes associated with the development of the central Sierra Nevada mountain range. The project involves geologic mapping and measurement of deformation fabrics and the building of a data bases that records deformation fabric, strain measurements. The fieldwork and digital database will be used to better understand processes that contribute to the localization of deformation in mountain belts during orogenic events. In addition to the scientific objectives of the study, the project is contributing to socially and nationally relevant goals, including the training of graduate and undergraduate students in an important STEM (Science, Technology, Engineering and Mathematics) discipline; development of a digital data base in a geographic information system (GIS) format that will be made available to the scientific community and the public; development of an extensive, integrated digital field guide to the geology of the region that can be used for teaching and research; and the development of virtual field trips that will be publically available. Undergraduate student training will involve participation in the university's UTR program, a multidisciplinary, learner-centered research experience that includes field studies followed by lab research, culminating in professional publications and presentations. Efforts will be made in this program to broaden the participation of underrepresented groups in the geosciences. The project involves international collaboration with a scientist from Canada, and the project will contribute to research infrastructure at the host institution. Results of the research will be made available through peer-reviewed publications in the scientific literature, presentations at professional society meetings, and public outreach through lectures at schools and national parks. Samples will be archived at the university, and digital data will be made available via university servers and community databases. In addition, all data will be shared with Yosemite National Park and other conservation area personnel.Rheological heterogeneity in orogens over the range of lithospheric observation scales leads to deformation partitioning of tectonic boundary conditions throughout intervening scales, making it unrealistic to apply single-scale models to connect small-scale structures to tectonic scale processes and boundary conditions. The proposed research is a multi-scale investigation aimed at connecting deformation processes, tectonics, and orogenic evolution using a state of the art, self consistent Multi-Order Power-Law Approach (MOPLA) which incorporates multi-scale deformation in its formulation and provides a rigorous means for bridging small-scale studies to tectonic-scale deformation conditions and processes. The relationship of tectonics to orogenic evolution and the resulting multi-scale deformation will be investigated by applying MOPLA to the data rich central Sierra Nevada where extensive multi-scale structural, strain, and petrological data linked to mapping and geochronology have been collected over several decades. These define an apparent Mesozoic history of episodic deformation, plate motions, and tectonic regimes that parallel episodic magmatism. A geographic information system (GIS)-based synthesis of new and existing datasets will be created and then integrated with MOPLA to construct and test multi-scale modeling predictions. This work will test the hypothesis that intra-orogenic deformation is partly controlled by evolving deformation partitioning that is further modulated by the thermal effects and volume addition related to episodic magmatism. This will be investigated through modeling to test four corollary, interrelated hypotheses: (1) Structural variations observed in the central Sierra Nevada at all scales often arise from time-dependent deformation partitioning rather than shifting plate motions. (2) Magmatic fabric orientations in central Sierra Nevada plutons represent local fabrics developed in partitioned flow fields rather than distinct increments of the bulk deformation field. (3) Episodic deformation is primarily driven by the effects of episodic magmatism. (4) Intra-orogenic bulk shortening is accommodated primarily by crustal thickening along broad, low strain domains rather than motion along localized, high strain zones. As single scale structural studies and plate motion reconstructions for older orogens are limited, forward modeling of multi-scale deformation will lead to a better understanding of how to integrate local observations to explore their regional significance.

该项目的重点是一个多尺度调查，旨在了解变形过程与中部塞拉内华达州山脉的发展。该项目涉及变形组构的地质测绘和测量，以及记录变形组构、应变测量的数据库的建立。实地工作和数字数据库将用于更好地了解造山活动期间有助于山区变形局部化的过程。除了研究的科学目标外，该项目还有助于实现社会和国家相关目标，包括在一个重要的STEM领域培训研究生和本科生。（科学、技术、工程和数学）学科;开发地理信息系统格式的数字数据库，供科学界和公众使用;开发一个可用于教学和研究的关于该区域地质的广泛、综合的数字实地指南;以及开发虚拟实地考察，将以电子方式提供。本科生培训将涉及参与大学的UTR计划，这是一个多学科的，以学习者为中心的研究经验，包括实地研究，然后是实验室研究，最终在专业出版物和演示文稿。该计划将努力扩大代表性不足的群体对地球科学的参与。该项目涉及与加拿大一名科学家的国际合作，该项目将有助于东道机构的研究基础设施。研究结果将通过科学文献中的同行评审出版物、专业协会会议上的演讲以及通过在学校和国家公园举办讲座的公众宣传来提供。样本将在大学存档，数字数据将通过大学服务器和社区数据库提供。此外，所有的数据将共享给约塞米蒂国家公园和其他保护区的personal.Rheological不均匀性在造山带的岩石圈观测尺度的范围内，导致变形分区的构造边界条件在整个干预尺度，使它不切实际的应用单尺度模型连接小规模的结构，构造规模的过程和边界条件。拟议的研究是一个多尺度的调查，旨在连接变形过程，构造和造山演化使用的最先进的，自洽的多阶幂律方法（MOPLA），其中包括多尺度变形的制定，并提供了一个严格的手段，桥接小规模的研究，构造规模的变形条件和过程。将MOPLA应用于数据丰富的中部Sierra内华达州，其中广泛的多尺度结构，应变和岩石学数据，与映射和地质年代学已收集了几十年的构造造山演化和由此产生的多尺度变形的关系进行了研究。这些定义了一个明显的中生代历史的幕式变形，板块运动和构造制度，平行幕式岩浆作用。将创建一个基于地理信息系统（GIS）的新数据集和现有数据集的合成，然后与MOPLA集成，以构建和测试多尺度建模预测。这项工作将测试的假设，造山带内的变形是部分控制不断变化的变形分区，进一步调制的热效应和体积增加有关的幕式岩浆活动。这将通过建模来研究，以测试四个推论，相互关联的假设：（1）在所有尺度上观察到的内华达州中部山脉的结构变化往往来自于与时间相关的变形分区，而不是移动板块运动。(2)在中部塞拉利昂内华达州岩体岩浆组构的方向代表当地的织物分区流场，而不是明显的增量的整体变形场。(3)幕式变形主要受幕式岩浆作用的影响。(4)造山带内的整体缩短主要是由地壳增厚沿着广泛，低应变域，而不是运动沿着局部，高应变区。由于单一尺度的构造研究和板块运动重建的老造山带是有限的，多尺度变形的正演模拟将导致更好地了解如何整合当地的观测，探索其区域意义。