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

这个多学科的合作项目评估的作用，岩石圈的沉降和沉积物的沉积在科迪勒拉前陆在白垩纪沉降引起的大洋构造板块俯冲下的北美西缘。这项研究有可能改变对岩石圈尺度过程的理解，方法是利用沉积和盆地分析、热年代学和地球动力学建模相结合的方法，澄清平坦俯冲对上地壳和盆地的影响，以便能够区分地壳负荷机制的相对贡献。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，扩大科学中代表性不足的群体的参与，培养博士后研究人员以及研究生和本科生来推动重要的社会成果。阿拉斯加大学的公共宣传工作和通过休斯顿大学与当地中学和中学年龄在家上学的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。该项目还支持参与的大学和工业之间建立新的伙伴关系，从而为提高美国的经济竞争力做出贡献。虽然迁移动力沉降长期以来一直被引用来解释晚白垩世沉积中心的扩大和迁移，但没有研究采取高分辨率，大规模的方法来表征迁移的时间或方向，或区分动态沉降的弯曲。然而，弯曲加载和地壳下加载留下不同的前陆盆地沉积物，记录沉积物源区和源区折返率，并有一个特征填充几何记录的轨迹和沉降率。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平坦俯冲对持续或增强的逆冲带折返或初期基底核隆起的潜在影响。科迪亚克系统提供了一个无与伦比的机会，建立在地球上最好的弧后前陆盆地系统的海洋高原的平坦俯冲的影响，因此，这项调查的结果是适用于其他海洋-大陆收敛系统。该研究小组正在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、挠曲和地球动力学建模，评估观察到的盆地结构变化机制。新的碎屑地质年代学和砂岩成分数据正在补充已发表的地质年代学和沉积学，以更准确地确定这段时间沉积物来源和路线的变化。碎屑热年代学描绘了滞后时间的上升段变化，对应于源折返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建模允许计算和比较平均沉积物供应量，以区分沉积物供应导致的盆地结构变化与沉积驱动的变化。目前正在利用详细的等厚图和地史分析来重建盆地沉降，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，使歧视的相对贡献的加载机制。该项目将联合收割机首次结合碎屑地质和热年代双重定年、高分辨率层序地层学以及能够区分沉降机制的规模和分辨率的多种模拟工作的优势。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NSF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而被认为值得支持。

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.