Pleistocene Paleointensity Record of Aleutian Island Volcanics

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This project is a geologic investigation aimed at furthering our understanding of the Earth's ancient magnetic field. The PI is working with the U.S. Geological Survey (USGS) in Anchorage, Alaska to collect lava flow samples from Tanaga Island in the Aleutian Island chain. Magnetic experiments on these lavas will allow the team to recover the strength of the Earth's ancient magnetic field in Alaska and use that information to evaluate the average behavior of the geomagnetic field over the last 500 thousand years. Paleomagnetic data (such as the paleointensity information collected as part of this project) play an important role in many geologic and geophysical applications, such as: performing plate tectonic reconstructions, determining the age of rock formations and timing of tectonic events, and developing models of the Earth's interior. This project will present the first high-quality paleointensity study of Alaskan lava flows, and will allow researchers to better understand how the geomagnetic field behaves at high northern latitudes. Effective analysis of ancient geomagnetic field structures requires the collection of global paleomagnetic data that are geographically and temporally distributed. Most published paleomagnetic data are from mid-latitudes, with relatively few studies targeting localities at equatorial and high latitudes ( 50°). A search of the online MagIC paleomagnetic database (http://earthreg.org/MAGIC) shows that only four studies are from Alaska, and none of them present any paleointensity data. This project will be the first high-quality paleointensity study in the region. The PI and students will sample volcanic material from 35 Pleistocene-age lava flows from Tanaga Island. All lava flows have been dated using 40Ar/39Ar geochronology methods by researchers with the U.S. Geological Survey. Paleointensity experiments will be conducted on all lavas, and the results will be compared to other high latitude data sets in northern and southern hemispheres. Evaluation of our intensity results will allow for new insights into the long-term regional behavior of the geomagnetic field in Alaska and the variability of the global field over time.