Early lunar magnetism
Abstract
WE have applied a new method1 for palaeointensity (ancient magnetic field) to three subsamples of a single, 1-m homogeneous clast (72215) from a recrystallised boulder of lunar breccia. Samples from the clast have been dated by 40Ar-39Ar (ref. 2), Rb-Sr (ref. 3) and U-Pb (ref. 4) methods to yield a date of 4.0×199 yr as the age of boulder assembly. The new method1 has two desirable characteristics; first, its reliance on simulating the natural remanent magnetisation (NRM) directly with a thermoremanent magnetisation (TRM); second, it includes a built-in monitoring device which detects thermally-induced sample degradation (oxidation, sintering and annealing), a common occurrence in lunar samples. We therefore provide here the first credible evidence that the strength of the ambient magnetic field at the Taurus-Littrow region of the Moon must have been about 0.4 oersted, 4.0×109 yr BP.
- Publication:
-
Nature
- Pub Date:
- March 1976
- DOI:
- 10.1038/260230a0
- Bibcode:
- 1976Natur.260..230B
- Keywords:
-
- Field Strength;
- Lunar Evolution;
- Lunar Magnetic Fields;
- Paleomagnetism;
- Breccia;
- Interplanetary Magnetic Fields;
- Magnetization;
- Solar Activity Effects;
- Solar Flares;
- Lunar and Planetary Exploration