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

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.

地质工艺从墨西哥西部延伸到阿拉斯加的山脉。在这种替代方案中，距离正常人的边缘。加利福尼亚该项目将提供四个PI，其中两个是女性，三位研究生本科生的博士学位工作和实验室经验是我的理想选择。在现场观察和定量分析的背景下，研究人员的近乎人物指导也将使美洲原住民学生在地质过程中的联系。 ND将结果沿美国的Cordillera纳入了该合作的局限器。随后的崩溃，4）使用碎屑锆石分析（U-PB，LU-HF和Trace Element Geochocemison）和全摇滚摇滚SM-ND同位素分析和痕量元素地球化学将提供拟议模型的大陆规模，以改善北美山脉的中生代发展。其他牛根系中的收敛系统，尤其是不是avai lable的轮子前的前生代系统。该奖项反映了NSF值得支持的支持评估，并使用Toundation IT和更广泛的影响评估标准进行评估。