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Effect of Shock on the Magnetic Properties of Pyrrhotite, the Martian Crust, and MeteoritesWe performed planar shock recovery experiments on natural pyrrhotite at pressures up to 6.9 GPa. We find that high-field isothermal remanent magnetization in pyrrhotite is demagnetized up to 90% by shock due to preferential removal of low coercivity components of magnetization. Contrary to static experiments, we do not observe complete demagnetization. Post shock permanent changes in magnetic properties include increasing saturation isothermal remanent magnetization, bulk coercivity and lowtemperature memory, and changes in squareness of hysteresis. These changes are consistent with an increase in the volume fraction of single domain grains. The lack of magnetic anomalies over large Martian impact basins is not expected to be solely due to shock demagnetization of the crust. We find that pyrrhotite-bearing rocks and meteorites can retain records of Martian magnetic fields even if shocked to pressures approaching 7 GPa. However, some paleointensity techniques may underestimate this field.
Document ID
20070034732
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Louzad, Karin L.
(Harvard Univ. Cambridge, MA, United States)
Stewart, Sarah T.
(Harvard Univ. Cambridge, MA, United States)
Weiss, Benjamin P.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Publication Information
Publication: Geophysical Research Letters
Publisher: American Geophysical Union
Volume: 34
Subject Category
Lunar And Planetary Science And Exploration
Funding Number(s)
CONTRACT_GRANT: NNX06AD14G
Distribution Limits
Public
Copyright
Other

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