نبذة مختصرة : Remote sensing analyses of data set taken by Clementine in 1994 permit new observations about mineral distribution on the lunar surface, basalt flow stratigraphy, and thus the geologic evolution of the Moon. The northern section of Oceanus Procellarum contains numerous impact craters which penetrated the basalt and thus can be used as natural probes to estimate the number and thicknesses of flows. I constructed a mosaic taken in three frequencies ( 415 nm, 750 nm, 950 nm), and a Ratio Image (750/415 = red, 750/950 = green, 415/750 = blue). On such an image, red indicates the iron-poor mature highland regolith and titanium-poor basalts; green, freshly exposed mafic surfaces; blue, titanium-rich basalts and immature (freshly exposed) highland regolith. Use of the iron mapping algorithm developed by Lucey et al. (1996) produced an Iron Image needed to identify the basalt strata exposed on crater walls. These images show that basalt flows in Oceanus Procellarum change in composition over time and that different basalt layers can be correlated over large areas based on their composition. The northern portion of the mare contains widespread titanium-rich mare basalt and is bounded on the West by highland that is covered by anorthositic regolith. In eastern Oceanus Procellarum, the large craters ' expose at least two basalt flows greater than 1 kilometre thick; a titanium-rich surface unit is underlain by a titanium-poor unit that itself is underlain by anorthositic basement. The western portion of the study area is covered by the titanium-poor basalt except where anorthosite crust protrudes or where craters punctured through to anorthosite basement. The titanium-rich basalts are estimated to be approximately 1 billion years old and the titanium-poor basalts, 3.3 billion years old. In northern Oceanus Procellarum (area of 525,000 square kilometres), the volume of basalt exceeds 240,000 cubic kilometres.
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