HR: 08:30h
AN: GP41C-03 INVITED     [Abstracts]
TI: Paleomagnetism of the Solar System.
AU: * Fuller, M
EM: mfuller@soest.hawaii.edu
AF: HIGP-SOEST, U. Hawaii, 1680, East-West Rd, POST 602, Honolulu, HI 96822 United States
AB: In addition to the paleomagnetic record from Earth, we have paleomagnetic results from samples from the Moon, Mars, and from a variety of meteorites. The record from the Moon involves numerous samples and appears to define a strong field interval from about 3.85 to 3.65 Ga. Subsequently the field may have turned off rapidly as some have advocated, or decayed over a period of billions of years as advocated by others. The record from Mars comes to us via the Martian meteorites, which include only one ancient rock ALH84001, a cataclastic pyroxenite. It has a crystallization age of 4.5 Ga. However, it was severely shocked at 4.0 Ga, from which time much of the magnetization probably originated. Estimates of the strength of the field in which it was magnetized vary, but it was probably at least a few microteslas. Younger volcanic rocks from Mars have given more reliable, but weaker field estimates. The paleomagnetic record from meteorites other than those from the Moon and Mars is probably the hardest of all records to interpret, but at least the achondrites may carry a record of fields on parent bodies. Besides the intrinsic interest in the paleomagnetism of samples from the solar system, the results provide some "groundtruth" to aid in the interpretation of the magnetic fields of the parent bodies. Such interpretations immediately encounter the role of shock on the magnetization of the recovered samples. Both on the Moon and Mars the effects of impacts and shock are pervasive on all scales. Indeed the least improbable model of lunar magnetism is related to giant impacts and on Mars the large impact basins play a key role.
DE: 1595 Planetary magnetism: all frequencies and wavelengths
DE: 5420 Impact phenomena, cratering (6022, 8136)
DE: 6225 Mars
DE: 6250 Moon (1221)
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005