Collaborative Research: Linking sediment dispersal, stratal architecture, and tectonic subsidence mechanisms in the Late Cretaceous Cordilleran Foreland Basin

这个多学科合作项目评估了科迪勒兰前陆的岩石圈沉降和沉积物沉积对白垩纪北美西部边缘海洋构造板块俯冲引起的沉降的响应。通过结合沉积和盆地分析、热年代学和地球动力学建模来区分地壳加载机制的相对贡献，阐明了平坦俯冲对上地壳和盆地的影响，该研究有可能改变对岩石圈尺度过程的理解。除了该项目的科学目标外，该合作还通过促进STEM（科学，技术，工程和数学）教育工作者的发展，扩大未被充分代表的科学群体的参与，培养博士后研究员以及研究生和本科生来推进重要的社会成果。阿拉斯加大学的公共宣传工作，以及通过休斯顿大学与当地中学和在家上学的中学生之间新建立的关系对中学生的教育，有助于提高公众的科学素养和公众对STEM的参与。该项目还支持在参与的大学和工业界之间发展新的伙伴关系，从而为提高美国的经济竞争力做出贡献。虽然迁移性动态沉降一直被用来解释晚白垩世沉积中心的扩展和迁移，但目前还没有研究采用高分辨率、大规模的方法来表征迁移的时间和方向，也没有研究采用高分辨率、大规模的方法来区分弯曲性和动态沉降。然而，弯曲载荷和地壳下载荷留下了不同的前陆盆地沉积，记录了沉积物的源区和源区挖掘速率，并具有记录沉降轨迹和速率的特征填充几何形状。对地层结构、沉积物体积、沉积物来源和沉积产物的详细调查使研究小组能够探索海洋高原的平坦俯冲对持续或增强的逆冲带挖掘或早期基底核隆升的潜在影响。科迪勒拉体系提供了一个无与伦比的机会，在地球上最具年代确定的弧后前陆盆地体系中建立海洋高原的平俯冲作用；因此，本文的研究结果也适用于其他洋陆辐合系统。研究小组通过整合砂岩成分数据、碎屑热年代学和地质年代学、高分辨率层序地层学、高分辨率等厚图、地史分析以及正演地层学、弯曲学和地球动力学模型，对观察到的盆地结构变化机制进行评估。新的碎屑地质年代学和砂岩成分数据补充了已发表的地质年代学和沉积学，以更准确地识别这段时间内沉积物物源和路线的变化。碎屑热年代学描述的是滞后时间向上剖面的变化，对应于源挖掘速率的变化，或新沉积物源的引入。层序地层学、解压缩等厚图和正演地层学模拟可以计算和比较平均沉积物供应，从而区分沉积物供应和调节驱动的盆地结构变化。利用详细的等深线图和地质历史分析完成了盆地沉降的重建，这有助于区分地壳负荷和地壳下负荷。最后，弯曲和地球动力学建模可以区分加载机制的相对贡献。该项目将首次结合碎屑地质和热年代学双测年、高分辨率层序地层学和多种建模工作的优势，在一定规模和分辨率下能够区分沉降机制。由于这种合作，该项目有可能通过澄清平坦俯冲对上地壳和盆地的影响来改变对岩石圈尺度过程的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This multidisciplinary collaborative project evaluates the role of subsidence of the lithosphere and deposition of sediments in Cordilleran foreland in response to Cretaceous subsidence caused by subduction of an oceanic tectonic plate beneath the western margin of North America. The research has the potential to transform understanding of lithosphere-scale processes by clarifying the effect of flat subduction on the upper crust and basins using a combination of sedimentary and basin analyses, thermochronology and geodynamic modelling to enable discrimination of the relative contributions of crustal loading mechanisms. In addition to the scientific goals of the project, the collaboration is advancing important societal outcomes by contributing to STEM (science, technology, engineering and mathematics) educator development, the broadening of participation of underrepresented groups in science, the training of a postdoctoral researcher and graduate and undergraduate students. Public outreach efforts by the University of Alaska and education of middle school students through newly established relationships between the University of Houston and local middle schools and middle-school aged homeschooled students contributes to increased public scientific literacy and public engagement with STEM. The project also supports the development of a new partnership between the participating universities and industry, thereby contributing to the increased economic competitiveness of the United States.Although migrating dynamic subsidence has long been invoked to explain the broadening and migration of the Late Cretaceous depocenter, no research has taken a high resolution, large-scale approach to characterizing the timing or direction of migration or to discriminate flexural from dynamic subsidence. However, flexural loading and subcrustal loading leave distinct foreland-basin deposits that record sediment source area and source area exhumation rate and have a characteristic fill geometry that records the locus and rate of subsidence. Detailed investigation of stratigraphic architecture, sediment volumes, sediment sources, and depositional products allows the research team to explore the potential influence of flat subduction of an oceanic plateau versus continued or enhanced thrust belt exhumation or incipient basement-cored uplifts. The Cordilleran system presents an unparalleled opportunity to establish the effect of flat subduction of an oceanic plateau in the best dated retroarc foreland basin system on the planet; thus, the results of this investigation are applicable to other ocean-continent convergent systems. The research team is evaluating mechanisms for observed changes in basin architecture by integrating sandstone compositional data, detrital thermo- and geochronology, high-resolution sequence stratigraphy, high-resolution isopach maps, geohistory analysis, and forward stratigraphic, flexural, and geodynamic modelling. New detrital geochronology and sandstone compositional data are supplementing published geochronology and sedimentology to more accurately identify changes in sediment provenance and routing during this time. Detrital thermochronology is delineating up-section changes in lag time, corresponding to changes in source exhumation rates, or introduction of a new sediment source. Sequence stratigraphy, decompacted isopach maps, and forward stratigraphic modelling allow calculation and comparison of the average sediment supply to discriminate changes in basin architecture due to sediment supply from accommodation-driven changes. Reconstruction of basin subsidence is being accomplished using detailed isopach maps and geohistory analysis, which facilitates discrimination of crustal loads from a subcrustal load. Finally, flexural and geodynamic modelling enables discrimination of the relative contributions of loading mechanisms. This project will combine, for the first time, the strengths of detrital geo- and thermochronological double-dating, high-resolution sequence stratigraphy, and multiple modeling efforts at a scale and resolution capable of discriminating the mechanisms for subsidence. As a result of this collaboration, this project has potential to transform the understanding of lithosphere-scale processes by clarifying the effect of flat subduction on the upper crust and basins.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.