2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 6
Presentation Time: 9:50 AM


YINGST, R. Aileen, Natural and Applied Sciences, University of Wisconsin-Green Bay, 2420 Nicolet Dr, University of Wisconsin - Green Bay, Green Bay, WI 54311 and PIERRE, N.M., University of Wisconsin-Green Bay, 2420 Nicolet Dr, University of Wisconsin - Green Bay, Green Bay, WI 54311, yingsta@uwgb.edu

Success of the new Lunar Exploration Initiative depends in part upon our ability to accurately assess and map the lunar surface materials, so that appropriate landing sites may be chosen for scientifically important goals. Current geologic maps of the Moon, however, are in some cases over thirty years old and do not integrate the wealth of compositional information that has been produced by more recent missions such as Clementine. We have utilized several disparate datasets to produce a new geologic map of the volcanic deposits at the Moon's north rim, to demonstrate how the blending of multispectral data with photogeologic information may facilitate a re-examination of geologic interpretations of familiar locations.

Using Lunar Orbiter and Clementine 0.750 µm images, we examined the morphology of 25 deposits on the north rim, mapping the area of each deposit, and estimating thickness and volume. Also noted were the age and mode of occurrence of each pond, as well as any features associated with it. Calibrated and corrected Clementine multispectral data were used to determine general pond mineralogy, to judge compositional homogeneity, and to confirm pond boundaries determined by morphological means. FeO and TiO2 weight percentage estimates derived from Clementine data and Th abundance derived from Lunar Prospector data were also noted.

Deposit areas ranged from 130 km2 to 8280 km2, with a median value of 1185 km2. Volumes ranged from 25 km3 to 6800 km3, with a median value of 340 km3. Such volumes are immense compared to typical historical terrestrial eruptions and are most comparable to large igneous provinces and flood basalts. Pond soil mineralogy conformed to basaltic norms, with an average FeO content of 14-18 wt% and typical TiO2 content of 1.5-4.5%. This categorizes deposits as low- to very low-TiO2 basalts. Thorium abundances ranged from 1.19 to 3.43 µg/g, averaging 2.20 µg/g. Such values are typical of soils surrounding the Procellarum and Imbrium regions. Multispectral and elemental datasets also revealed variations in composition that were invisible to previous missions, but have allowed us to redraw the maps of these deposits. Approximately 10% of the deposits previously mapped as single flows have been determined to have characteristics consistent with multiple flows.