SCIENCE HIGHLIGHT

Planetary Geodynamics Laboratory, Code 698

May 2005

Purucker and Whaler Paper Accepted by JGR - Planets

New Model of Mars Crustal Magnetization Anomalies has Tectonic Detail

Mike Purucker is a senior staff geophysicist with Raytheon Technical Services in the Planetary Geodynamics Lab and has worked at the Goddard Space Flight Center for 15 years. He is well-known for studies of crustal magnetic anomalies on both Earth and Mars, and is a member of the Mission Advisory Group for the European Swarm Mission. Kathy Whaler is the former chair of Geology and Geophysics and now Professor of Geophysics in the School of Geosciences at Edinburgh University, Scotland.

Purucker and Whaler have cooperated on a number of terrestrial and martian magnetic studies, and in a previous paper on Mars crustal anomalies (2003) identified a magnetic feature associated with an old martian volcano with a signature like that of Earth's triple junctions.

Since their discovery by Mars Global Surveyor, remanent crustal magnetic anomalies on Mars have been modeled by a variety of authors, although the actual sources of these anomalies remain a mystery. Now Mike Purucker and Kathy Whaler have a new model which uses techniques applicable to sparse data sets. This better preserves the resolution of the original spacecraft data. In this model the authors see evidence for both generation and destruction of magnetized crust related to tectonic, volcanic and impact events and when they occurred compared to the time when the global magnetic field of Mars died.

Radial component of magnetization in the new model by Purucker and Whaler, now in press

The new model is described in a paper "A Spatially Continuous Magnetization Model for Mars" which was recently accepted for publication in the Journal of Geophysical Research (Planets). It assumes a magnetized layer 40 km thick, adapts techniques developed by themselves and others for both terrestrial and martian magnetic anomalies, and yields a model with considerable detail (above) which compares favorably with previous models (below).

Comparison of the current model with other published models

Purucker and Whaler identify two old volcanic features on Mars which have prominent magnetic signatures. Both also have associated gravity anomalies, and are much older than the large Tharsis volcanoes, which have no recognizable magnetic signatures.

Contacts: Mike Purucker, GSFC Code 698, purucker AT geomag DOT gsfc DOT nasa DOT gov

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Responsible NASA official: Dr. Herbert Frey