enhanced Thorium abundance map from Geophysics Research Letters
The element thorium (Th) is critically important on the Moon because it is a tracer for the ancient igneous material KREEP. KREEP is largely concentrated in the northwestern quadrant of the Moon, being mostly restricted to the area within the putative Procellarum basin. Because Th is a radioactive element it can be detected from orbit, but the gamma ray spectrometer on the Lunar Prospector spacecraft yielded a coarse resolution of about 80 km. Now, D.J. Lawrence and colleagues have applied improved methods of spatial deconvolution - fancy words for statistically enhancing resolution - yielding this new map with a resolution of 30-40 km. This improved view more clearly shows enhanced Th abundance and KREEP associated with specific features. The craters Aristarchus, Marian, Aristillus, Timocharis, Kepler, Euclides, Lalande, Bulliadus and north of Manners all have local highs. Also interesting are the Th holes at Copernicus and Plato - did those craters excavate through and remove the KREEP?
Lawrence, D. J.; Puetter, R. C.; Elphic, R. C.; Feldman, W. C.; Hagerty, J. J.; Prettyman, T. H.; Spudis, P. D. Global spatial deconvolution of Lunar Prospector Th abundances. Geophys. Res. Lett., Vol. 34, No. 3, L03201 10.1029/2006GL028530; 07 February 2007.
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