Collaborative Research: Clockwise block rotation in the Pacific Northwest and sinistral movement on the Lewis & Clark zone

合作研究：太平洋西北地区的顺时针地块旋转和刘易斯河的左旋运动

• 批准号: 2317913
• 负责人: Basil Tikoff
• 金额: $ 43.91万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317913&HistoricalAwards=false
• 关键词: Collaborative; Research; Clockwise; block; rotation

GeneralThe western portion of the North American continent was assembled by collision of large blocks of crust over the past 200 million years. These collisions are likely responsible for the formation of mountain belts, significant igneous activity, and production of mineral deposits throughout the western United States. This project will gather data from rocks in Idaho and Montana to test new ideas to explain the timing and origin of the mountain building events in the northern Rocky Mountains and Pacific Northwest. The ideas to be tested include the type of crustal movement, the timing of those crustal movements, and the deformation of rocks associated with it. Predictions resulting from these ideas include the existence of clockwise rotation of large portions of Idaho, Oregon, and Montana. The Lewis & Clark zone of Idaho and Montana - a large-scale strike-slip fault - may have resulted from these clockwise rotations. The work conducted for this project will include collection of samples to measure the direction of the Earth’s magnetic field recorded when the rocks formed, and to analyze minerals in these rocks to determine their age. This data will test predictions for the timing of deformation and of associated igneous activity. The work will be done by a team of faculty at two universities, three graduate students, and several undergraduate students.The proposal is a straightforward paleomagnetic test of whether the Blue Mountains and Adjacent Laurentia – the region of eastern Oregon, southeastern Washington, central Idaho, and possibly southwestern Montana – rotated ~30° clockwise as a coherent block in the Late Cretaceous-Paleogene. A series of paleomagnetic analyses will be conducted on different locations to test whether the clockwise rotation happened and, if so, what is the spatial extent of the crustal block. Paleomagnetic analyses of different ages of rocks will test when the clockwise rotation occurred, to correlate it to motions along the western margin of Laurentia and contractional deformation in the continental interior. The implications are three-fold. First, clockwise rotation could provide independent evidence for dextral terrane translation along the western margin of the Pacific Northwest. Second, the clockwise rotation may explain the activation of the Lewis and Clark line, a major strike-slip system that is oblique to the plate margin. The timing of clockwise rotation should act as a guide to the history of left-lateral vs. right-lateral movement on that structure. Third, the rotation of the Blue Mountains- Adjacent Laurentia block may be spatially and temporally correlated with Laramide-style deformation in its type locality, it could inform questions about foreland deformation. The work will support three graduate students from Western Washington University and the University of Wisconsin-Madison. It will also support undergraduate student research and a capstone experience for undergraduate students at each university.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.

北美大陆的西部将军是在过去的2亿年中大块地壳碰撞的。这些碰撞可能是造成山带的形成，重要的火成活性以及整个美国西部的矿藏的生产。该项目将收集来自爱达荷州和蒙大拿州的岩石的数据，以测试新想法，以解释北洛矶山脉和西北太平洋山区建筑事件的时机和起源。要测试的想法包括地壳运动的类型，这些地壳运动的时机以及与之相关的岩石的变形。这些想法产生的预测包括存在爱达荷州，俄勒冈州和蒙大拿州大部分地区的顺时针旋转。爱达荷州和蒙大拿州的刘易斯和克拉克区 - 大规模滑滑 - 可能是由这些顺时针旋转造成的。该项目进行的工作将包括样品的收集，以测量岩石形成时记录的地球磁场的方向，并分析这些岩石中的矿物质以确定其年龄。该数据将测试预测变形时间和相关的火成活性。这项工作将由两所大学，三名研究生和几名本科生的一组团队完成。该提案是对蓝山和邻近的劳伦蒂亚（Laurentia）是否是一项直接的古磁性测试，是否是俄勒冈州东南部，华盛顿州东南部，爱达荷州中部，可能是蒙大拿州西南部 - 旋转的30°°c Crote crotece coterace the Crote cotere cotere coterene coterene。将在不同位置进行一系列古磁分析，以测试顺时针旋转是否发生，如果是的，则是地壳块的空间范围。何时出现顺时针旋转时，将测试岩石不同年龄的古磁分析，以将其与沿Laurentia西部边缘的运动和连续内部的收缩变形相关。含义是三个方面。首先，顺时针旋转可以为西北太平洋西部边缘的右旋地层翻译提供独立的证据。其次，顺时针旋转可以解释刘易斯和克拉克线的激活，这是一个主要的滑滑系统，倾斜到板缘。顺时针旋转的时机应充当该结构上左侧运动与右侧运动历史的指南。第三，蓝山脉的旋转 - 相邻的月桂块可以在空间和临时与Laramide式的型号变形相关，它可以为前陆变形提供问题。这项工作将支持西部华盛顿大学和威斯康星大学麦迪逊分校的三名研究生。它还将支持每所大学的本科生研究本科生研究和顶峰经验。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评估，被认为是珍贵的支持。