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AGU: Geophysical Research Letters

 

Keywords

  • Mars
  • paleomagnetism
  • ALH 84001

Index Terms

  • Geomagnetism and Paleomagnetism: Planetary magnetism: all frequencies and wavelengths
  • Geomagnetism and Paleomagnetism: Paleointensity
  • Planetary Sciences: Solar System Objects: Mars
  • Planetary Sciences: Solar System Objects: Meteorites and tektites

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L23207, 5 PP., 2008
doi:10.1029/2008GL035585

Paleointensity of the ancient Martian magnetic field

Benjamin P. Weiss

Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

Luis E. Fong

Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA

Hojatollah Vali

Department of Anatomy and Cell Biology and Facility for Electron Microscopy Research, McGill University, Montreal, Quebec, Canada

Department of Earth and Planetary Sciences, McGill University, Montreal, Quebec, Canada

Eduardo A. Lima

Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

Franz J. Baudenbacher

Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA

Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA

Mars today has no core dynamo magnetic field. However, the discovery of remanent magnetization in Martian meteorites and intense crustal magnetization suggests that Mars once had a global field. Here we present high resolution maps of the magnetic field of Martian meteorite ALH 84001. These maps are the most sensitive yet quantitative study of natural remanent magnetization (with resolved anomalies as weak as 1 × 10−14 Am2). ALH 84001 likely contains a 4 billion year old (Ga) thermoremanence partially overprinted by one or more poorly understood secondary components. Our data suggest that the paleointensity of the local paleofield was within an order of magnitude of that of the present-day Earth. If this field were global in extent, it should have played a key role in Martian atmospheric and climatic evolution. However, it is still too weak to easily explain the intensity of Martian crustal paleomagnetic anomalies.

Received 13 August 2008; accepted 30 October 2008; published 13 December 2008.

Citation: Weiss, B. P., L. E. Fong, H. Vali, E. A. Lima, and F. J. Baudenbacher (2008), Paleointensity of the ancient Martian magnetic field, Geophys. Res. Lett., 35, L23207, doi:10.1029/2008GL035585.

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