Collaborative Research: Testing competing models for the origin and magma transport dynamics of the Columbia River LIP

合作研究：测试哥伦比亚河 LIP 的起源和岩浆输送动力学的竞争模型

• 批准号: 1946545
• 负责人: John Wolff
• 金额: $ 5.67万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1946545&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; competing; models

he Pacific Northwest of the United States is an area that has been impacted by volcanic eruptions for millions of years. Particularly notable are the many huge eruptions that produced the Columbia River Basalts (CRB) between 17 and 6 million years ago. The CRB lavas inundated Oregon and Washington, producing thick stacks of lava, in places of thousands of feet or more, and covering in excess of 150,000 square miles. Such voluminous lava outpourings are Earth’s biggest volcanic events and understanding them is key to understanding fundamental aspects of the dynamic behavior of our planet. Lavas of the CRB were fed from fissure eruptions similar to those observed today on Hawaii, Iceland, or at other areas with active basalt volcanism, but much much larger in scale. In recent years, it has become clear the magmas feeding such events can travel long distances laterally underground, instead of vertically from an underlying melt source prior to their eruption. This study will address whether CRB magmas travelled in the subsurface for long distances, and where the magma storage sites were located, to better understand where magmas from the deep Earth interior ( 40 km) ascended to the surface.This study will combine geochronological, geochemical, and rock magnetic techniques to examine magma flow within Columbia River feeder dikes, and thus will test models of magma transport. Along-strike variations in the age, chemistry, and flow direction in the ~400 km-long Columbia River dike system will be examined to constrain regional-scale magma transport dynamics in the plumbing system of this Large Igneous Province (LIP). This multidisciplinary approach will provide the first dataset of magnetic flow for Columbia River LIP dikes and to supply new and critical constraints on the timing and dynamics of magma emplacement in the province, which are currently lacking. Key questions related to Columbia River LIP magmatism that can be addressed with the new data include: 1) Did Columbia River LIP magmas originate from the inferred inception position of the Yellowstone hotspot at the Nevada-Oregon border? 2) Were there discrete zones of magma storage, from which magma travelled laterally away to feed flood lavas? 3) Over what timescales were dike swarms emplaced, and did the site of magmatism progressively migrate northward away from the Yellowstone hotspot? This project will support graduate and undergraduate students at two institutions, and build an international collaboration with faculty and students at the University of Auckland, NZ. The PI team will also run field workshops for local high school teachers in both Oregon and Washington.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.

美国西北太平洋地区数百万年来一直受到火山喷发的影响，尤其值得注意的是 17 至 600 万年前产生的哥伦比亚河玄武岩 (CRB) 的多次大规模喷发。俄勒冈州和华盛顿州产生了厚厚的熔岩堆，高度达数千英尺，覆盖面积超过 150,000 平方英里。喷发是地球上最大的火山事件，了解它们是了解地球动态行为基本方面的关键。 CRB 的熔岩来自裂缝喷发，类似于今天在夏威夷、冰岛或其他玄武岩火山活动活跃的地区观察到的情况。 ，但规模要大得多，近年来，很明显，这些事件的岩浆可以在地下横向移动很长的距离，而不是在喷发前从底层熔体垂直移动。解决CRB岩浆是否在地下长距离移动以及岩浆储存地点位于何处，以更好地了解来自地球内部深处（40公里）的岩浆在何处上升到地表。这项研究将结合地质年代学、地球化学和岩石学磁技术来检查哥伦比亚河支流堤坝内的岩浆流，从而测试约 400 公里长的哥伦比亚河堤坝系统中岩浆输送的沿走向变化模型。这种多学科方法将为哥伦比亚河 LIP 岩脉提供第一个磁流数据集，并为时间和动态提供新的关键约束。目前缺乏与哥伦比亚河 LIP 岩浆活动有关的关键问题，这些问题可以用新数据解决：1) 哥伦比亚河 LIP 岩浆是否起源于黄石的推断起始位置。内华达州和俄勒冈州边境的热点地区是否存在，岩浆从这些区域横向移动以供给洪水熔岩？ 3）岩墙群在什么时间尺度上形成，岩浆活动的地点是否逐渐向北迁移？该项目将为两个机构的研究生和本科生提供支持，并与新西兰奥克兰大学的教师和学生建立国际合作关系。还为俄勒冈州和华盛顿州的当地高中教师举办了实地研讨会。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。