Collaborative Research: RUI: Continental-Scale Study of Jura-Cretaceous Basins and Melanges along the Backbone of the North American Cordillera-A Test of Mesozoic Subduction Models

合作研究：RUI：北美科迪勒拉山脊沿线汝拉-白垩纪盆地和混杂岩的大陆尺度研究——中生代俯冲模型的检验

• 批准号: 2346567
• 负责人: Devon Orme
• 金额: $ 18.48万
• 依托单位: Montana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2346567&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Continental; Scale; Collaborative; Research; RUI; Continental; Scale

The geologic processes that formed the North American Cordillera, mountains that extend from western Mexico to Alaska, are disputed. These mountain ranges and neighboring basins (such as the Sierra Nevada and Great Valley basin within California) are conventionally interpreted to have formed due to eastward subduction of an oceanic plate beneath the western margin of the North American continent. Recent studies challenge this model and propose that much of the western Cordillera formed as an archipelago above westward subduction of an oceanic plate far from the margin of North America. In this alternative model, the archipelago became part of the Cordillera when the North American continent collided with the archipelago. This continental-scale study will test these models along four east-west transects across the western Cordillera in central Alaska, SE Alaska, British Columbia, and California. The project will provide support for four PIs, two of whom are female, the PhD work of three graduate students, and each PI’s commitment to provide undergraduate students with authentic field and laboratory experiences. The research methods are ideal for training undergraduate students to think across a range of spatial and temporal scales in the context of field observations and quantitative analyses, and undergraduate students will benefit from near-peer mentoring by graduate students. The researchers will also lead a multi-day field trip for Native American students centered on the connections between geologic processes that formed western North America and the homelands of Indigenous communities. The research addresses the fundamental problem of determining subduction polarity along ancient convergent margins. This project will couple the study of mélange belts with basin strata, and integrate the results along the hypothesized continental-scale suture within the North American Cordillera. This collaborative project will evaluate 1) the age and provenance of mélange belts, 2) the basins’ structural and sedimentological configuration (including inboard and outboard contacts), 3) the timing of basin formation and subsequent collapse, and 4) basin and mélange provenance comparison in the context of east-dipping versus west-dipping subduction. Analysis of the basin strata and adjacent mélange belts using detrital zircon analysis (U-Pb, Lu-Hf, and trace element geochemistry), sandstone petrography, and whole-rock Sm-Nd isotopic analysis and trace-element geochemistry will provide a continental-scale test of proposed models to better understand the Mesozoic development of the North American Cordillera. This project will also refine methods for establishing the geometry and timing of convergent margin systems in other orogens, particularly pre-Mesozoic systems for which tomographic information is not available.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.

构成了从墨西哥西部到阿拉斯加的北美山脉的地质过程。这些山脉和邻近的低音（例如内华达山脉和加利福尼亚州内的大山谷盆地）通常被解释为由于向东俯冲的北美大陆西部边缘下方的海洋板而形成。最近的研究挑战了这一模型和提议，即西方山脉的大部分地区都是远离北美边缘的海洋板的西方俯冲上方的群岛。在这种替代模型中，当北美继续与群岛合并时，该群岛成为了Cordillera的一部分。这项连续规模的研究将沿着阿拉斯加中部，阿拉斯加塞拉斯加，不列颠哥伦比亚省和加利福尼亚州的西部科迪利拉的四个东西方面测试这些模型。项目将为四个PI提供支持，其中两名是女性，三位研究生的博士学位工作，以及每个PI致力于为本科生提供真实的领域和实验室经验的承诺。研究方法是培训本科生在现场观察和定量分析的背景下跨越一系列空间和临时量表的理想选择，而本科生将受益于研究生的近点心态。研究人员还将为以地质过程与形成北美西部的地质过程与土著社区的家园之间的联系进行多天的现场旅行。该研究解决了确定沿古代融合边缘的俯冲极性的基本问题。该项目将将对混合带的研究与盆地地层进行研究，并将结果整合到北美山脉内的假设连续规模的缝合线。该协作项目将评估1）Mélange皮带的年龄和出处，2）贝斯的结构和沉积学配置（包括板和舷外触点），3）3）盆地形成和随后的倒塌的时机，以及4）盆地和梅兰奇出处比较，在向外的围绕向外围绕的替补替补互动的副本上比较。使用碎屑锆石分析（U-PB，LU-HF和Trace Element Geochemistry），砂岩岩石学以及全摇滚SM-ND同位素分析和痕量元素地球化学将对建议的模型，以更好地了解Mesozoic的Cordillera，对盆地层和相邻的混合带分析（U-PB，LU-HF和Trace Element Geochemistry），砂岩岩石学和全摇滚SM-ND同位素分析和痕量元素地球化学将提供更好的模型，以更好地了解Mesozoic Cordillera的Mesozoic开发。该项目还将完善用于在其他or元中建立融合利润系统的几何形状和时间安排的方法，尤其是在中生代的前系统中，无法使用层析成像信息。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准来通过评估来诚实地支持。