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

点击翻译按钮获取中文摘要

The 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.