Collaborative Research: Interrelations Between Foreland Deformation and Flat-slab Subduction: Integrated Analysis of the Sierras Pampeanas to Cordillera of the South-central Andes

合作研究：前陆变形与平板俯冲之间的相互关系：安第斯山脉中南部潘皮亚纳斯山脉至科迪勒拉山脉的综合分析

• 批准号: 1347558
• 负责人: W.A. Yonkee
• 金额: $ 13.56万
• 依托单位: Weber State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1347558&HistoricalAwards=false
• 关键词: Collaborative; Research; Interrelations; Between; Foreland

The modern-day topography of western South America results from the convergence and collision of two tectonic plates wherein the Nazca Plate is being shoved at a shallow angle beneath the South American plate in a process called subduction. This project will address the effects of flat-slab subduction in producing the continental deformation that has resulted in the dramatic uplift of the Andes along the western margin of South America. The PIs seek to provide better understanding of the geologic and geodynamic processes that have resulted in the growth of the Argentine Andes, and their results will have important implications for the understanding of ancient mountain building processes, such as the tectonic processes that formed the Rocky Mountains of the western United States during the Sevier and Laramide orogenies. The project involves a significant scientific collaboration with Argentinian geoscientists from the Argentina National Council of Scientific and Technical Research (CONICET) and their students, who will be involved in all facets of the project. The project will contribute to the training of undergraduate students through involvement of students in high-impact research projects and participation in cross-cultural international experiences; it will also contribute to the broadening of participation of underrepresented groups in STEM. Results of the research will be incorporated into research curricula and will be widely disseminated through presentations at meetings and publications. The project also has the potential to improve understanding of seismic risks in the study region that has experienced multiple devastating historic earthquakes. First-order questions persist regarding fundamental controls of continental deformation along convergent plate margins, including causes and interactions of thin-skin upper crustal to thick-skin lower crustal deformation, influences of pre-existing crustal weaknesses, and relations to subduction dynamics. This project will integrate a variety of structural and rock magnetic techniques in order to better understand the spatial and temporal changes in deformation that have resulted from flat slab subduction of the Naza plate and its interaction with the overriding South American plate. The project will involve the measurement and analysis of faults, folds, and fracture systems; measurements of the anisotropy of magnetic susceptibility to characterize deformation fabrics; will utilize paleomagnetic analysis to understand how crustal blocks have rotated due to deformation; and will use construction of geological cross-sections utilizing geophysical data. The work will focus on five transects that span the effects of normal to flat-slab subduction, and which cross the thick-skin Sierras Pampeanas, thin-skin Precordillera, and mixed mode Principal Cordillera belts of northwest Argentina. The project will: quantify both vertical-axis rotations and spatial-temporal changes in stress/strain fields across a complex mountain system (thick-skin foreland, thin-skin fold-thrust belt, mixed mode belt); provide a new model for the 3-dimensional kinematic evolution of the region; test geodynamic models that predict different along-strike variations in structural style, stress patterns, rotations, and intraplate shortening rates related to a transition from normal to flat-slab subduction; evaluate effects of crustal rheology, basement weaknesses, and basin inversion on patterns of structural trend, stress refraction, and deformation partitioning; and statistically compare stress/strain directions estimated from fault data, magnetic fabric analysis, earthquake focal mechanisms, and available global positioning satellite data.Funds to support the international activities associated with this project are being provided by the NSF Office of International Science and Engineering.

西南美洲西部的现代地形是由两个构造板的收敛和碰撞引起的，其中纳斯卡板在南美板块下方的浅角度被推入俯冲的过程。该项目将解决扁平俯冲俯冲在产生大陆变形方面的影响，这导致了南美西部边缘的安第斯山脉的急剧提升。 PI寻求更好地理解导致阿根廷安第斯山脉增长的地质和地球动力学过程，其结果将对对古代山区建筑过程的理解，例如形成塞维尔和拉米德尔剂造成美国西部洛矶山脉的构造过程具有重要意义。该项目涉及与阿根廷国家科学技术研究理事会（CONICET）及其学生的阿根廷地球科学家进行的重大科学合作，他们将参与该项目的所有方面。该项目将通过学生参与高影响力的研究项目并参与跨文化国际经验来为本科生的培训做出贡献；它还将有助于扩大STEM代表性不足的群体的参与。研究结果将纳入研究课程，并通过会议和出版物的演讲广泛传播。该项目还有可能提高对经历过多次毁灭性历史地震的研究地区地震风险的理解。关于沿收敛板边缘的大陆变形的基本控制的一阶问题，包括薄皮上皮与厚皮肤下层地壳变形的原因和相互作用，预先存在的地壳弱点的影响以及与降落动力学的关系。该项目将整合各种结构和岩石磁技术，以更好地了解由Naza板的平板俯冲及其与南美洲压倒式板的相互作用所产生的变形的空间和时间变化。该项目将涉及故障，褶皱和断裂系统的测量和分析；测量磁化性织物的磁敏感性的各向异性的测量；将利用古磁分析来了解由于变形而导致的地壳块如何旋转；并将利用地质横截面的构建利用地质物理数据。这项工作将集中于五个横断面，跨越了正常俯冲到平板俯冲的影响，并穿过厚皮的sierras pampeanas，薄皮precordillera和阿根廷西北部的混合模式主山脉腰带。该项目将：量化垂直轴旋转和横跨一个复杂山脉系统的应力/应变场的空间变化（厚皮的前陆，薄皮折叠皮带，混合模式皮带）；为该地区的三维运动学演化提供了新模型；测试地球动力学模型，这些模型在结构样式，应力模式，旋转和板间缩短率与从正常俯冲到平面俯冲的过渡有关的结构样式，应力模式，旋转和板间缩短率不同；评估地壳流变学，地下室弱点和盆地倒置对结构趋势，应力折射和变形分配模式的影响；并从统计学上比较了根据故障数据，磁性织物分析，地震焦点机制和可用的全球定位卫星数据估计的压力/应变方向。资金支持与该项目相关的国际活动的资金由NSF国际科学和工程办公室提供。