Origin of the Columbia River Basalts and Uplift of the Wallowa Mountains

哥伦比亚河玄武岩的起源和瓦洛厄山脉的隆起

• 批准号: 0511000
• 负责人: Eugene Humphreys
• 金额: --
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0511000&HistoricalAwards=false
• 关键词: Origin; Columbia; River; Basalts; Uplift

The Yellowstone hotspot initiated about 16.5 m.y. ago with a flood basalt eruption concentrated in NE Oregon. The origin of this event is not clear, nor is its overall effect on the lithosphere. This study will help us to understand how the Yellowstone hotspot began and the processes within the continental lithospheric. Several observations seem inconsistent with the plume hypothesis: there was no pre-eruptive uplift, magmatic fissuring occurred from a narrow but 700 km-long zone, and the main focus of magmatism occurred far off of the current Yellowstone hotspot track. This is a particularly suitable location for this study; nowhere else is there such a large, well-exposed, young and accessible area of continental growth interior to the continent. The investigators will deploy 25-station teleseismic stations coordinated with the USArray deployment in the Wallowa area to image basic crustal and upper mantle structure in NE Oregon and nearby regions. This is the region from which the greatest basalt eruption occurred, and it is that which witnessed a remarkable uplift event that created a bull's eye pattern of relief with the Wallowa pluton at its center. The seismic investigation will be augmented with a focused set of geodynamic models to test a range of hypotheses in a manner that enforces mass and heat conservation and force balance under the constraints of realistic rheologic behavior.The research plan of this proposal is designed to improve on the methods used to understand Earth processes by using geodynamic computer models to quantitatively relate hypotheses and a range of observations, and by studying a region with a teleseismic array of crustal-scale resolution embedded within a national array (USArray) of lithospheric-scale resolution. This project will prepare students and post-docs for the future through collaborations, participation in a diverse set of disciplines, and integration of the range of findings into consistent results.

黄石公园的热点始于大约1650万年前。前与洪水玄武岩喷发集中在东北俄勒冈州。这一事件的起源尚不清楚，其对岩石圈的总体影响也不清楚。这项研究将有助于我们了解黄石热点如何开始和大陆岩石圈内的过程。一些观察似乎与羽流假说不一致：没有爆发前的隆起，岩浆裂缝发生在一个狭窄但700公里长的区域，岩浆活动的主要焦点发生在远离当前黄石热点轨道的地方。 这是一个特别适合进行这项研究的地点;在非洲大陆内部，没有任何其他地方有如此大的、暴露良好的、年轻的和可进入的大陆生长区。调查人员将在瓦洛厄地区部署25个与美国阵列部署相协调的地面观测站，以成像东北俄勒冈州和附近地区的基本地壳和上地幔结构。这是最大的玄武岩喷发发生的地区，它见证了一个显着的隆起事件，创造了一个以瓦洛瓦岩体为中心的牛眼状浮雕图案。地震调查将增加一套有重点的地球动力学模型，以在现实流变行为的约束下，以强制执行质量和热量守恒以及力平衡的方式来测试一系列假设。本提案的研究计划旨在改进用于理解地球过程的方法，方法是使用地球动力学计算机模型将假设与一系列观测定量联系起来，并通过研究一个地区的地壳尺度分辨率嵌入在一个国家阵列（USAray）的岩石圈尺度分辨率的微重力阵列。该项目将通过合作，参与各种学科，并将一系列发现整合为一致的结果，为学生和博士后的未来做好准备。