Physical Sciences and Mathematics Commons^™

Unblocking Temperatures Of Viscous Remanent Magnetism In Displaced Granitic Boulders, Icicle Creek Glacial Moraines (Washington, Usa), Juliet G. Crider, Danika M. Globokar, Russ F. Burmester, Bernard A. Housen

Geology Faculty Publications

Viscous remanent magnetization (VRM) may partially overprint original magnetization in rocks displaced by geomorphic events. An established theoretical relationship between the time and temperature of acquisition of VRM and the time and temperature of demagnetization suggests that laboratory demagnetization (unblocking) of VRM can be used to estimate the displacement age of rocks. We test this hypothesis at four nested glacial moraines in the Icicle Creek drainage of central Washington, the ages of which were previously determined by cosmogenic surface exposure dating. The moraines are composed primarily of granodiorite boulders, and magnetic remanence is carried dominantly by magnetite. Both the maximum …