Regional magnetic anomaly data from both satellites and aeromagnetic surveys have provided substantial impetus for studies of the magnetic structure of the lower crust and upper mantle. The interpretation of these anomalies has remained a puzzle, requiring strongly magnetic source rocks that are thicker, more extensive, and perhaps deeper-seated than previously thought. A rock magnetic phenomenon has been called upon to explain the necessary intense magnetization of these deeper rock units: 'thermally enhanced' viscous remanent magnetization (VRM). The PI will test this hypothesis, with a suite of laboratory experiments to characterize the magnetic changes associated with VRM acquisition. Further, he will conduct these VRM experiments as a function of temperature, pressure, grain size and composition of the magnetic minerals, as well as the previous magnetic history of the samples, in an attempt to put closer limits on models of possible deep crustal magnetic sources.
