PRELIMINARY PALEOMAGNETIC INVESTIGATIONS OF JURASSIC EXTRUSIVES FROM VIRGINIA AND NORTH CAROLINA

The Mesozoic is a dynamic era of Earth’s geomagnetic history, containing both one of the longest periods of one single polarity (the Cretaceous Normal Superchron) as well as the Jurassic “Quiet Zone”, an interval marked by frequent polarity reversals (>10/myr). Attempts to explain these phenomena invoke large-scale crust-to-mantle-to-core controls, potentially related to subduction cycles and/or evolving mantle heterogeneities, or the stochastic end-members of the core convective processes that drive polarity reversals and secular variation. Beyond recording variations of deep Earth processes, changes in the intensity or morphology of the magnetic shielding of Earth’s outer atmosphere can influence the effects of space climate and the production of cosmogenic nuclides at the surface. Paleomagnetic observations from the rock record provide essential tests and constraints on geomagnetic models. Bridging the paleomagnetic history between these intervals is therefore critical to testing these hypotheses. Here we present preliminary results of a pilot study of Early and Late Jurassic intrusives from the Southeastern United States, including novel results from dikes of the North Carolina Eastern Piedmont, and discuss their potential for investigating core and deep mantle processes during the Mesozoic.