COPERNICUS 1:2.5M SCALE MAPPING: STATUS OF THE LUNAR GEOLOGIC MAPPING PILOT PROJECT

As part of a new, systematic lunar mapping program, we are using new digital data of the Moon in a ‘geodatabase' format to complete a 1:2.5M scale geologic map of the Copernicus crater quadrangle (0°-30°N, 0°-45°W). This quad contains Copernicus and Eratosthenes craters, both type localities of impact crater-related geologic units that formed the basis for the original lunar stratigraphic mapping by Shoemaker and others. Primary basemaps include a LO-IV photomosaic (60 m/px), Clementine UVVIS 5-band (100 m/px,) and NIR 6-band data (500 m/px), and UVVIS ‘standard' color ratios (R=750/415 nm; G=750/950 nm; B=415/750 nm). These data are augmented by Clementine topographic data (1 km/px), derived optical maturity (OMAT), and other data for interpreting soil com-position and physical properties. Major goals of this work are to demonstrate the integrated use of these photo-graphic and color image data for geologic unit mapping and characterization. With the stratigraphy of Wilhelms (1987) as a starting point, we are using color and maturity information from Clementine to identify highland, vol-canic, and crater-related units. One emphasis of this work is a local and regional characterization and refinement of the boundary between time-stratigraphic units of the Copernican and Eratosthenian Periods using optical maturity data. Preliminary mapping shows a substantially more diverse—both compositionally and temporally—and complex series of geologic units than have been previously mapped in the Copernicus quadrangle.

As a result of this work, we have identified optimal base maps, a mapping scale, and unit discrimination parameters that are appropriate for future geologic mapping by us and others across the Moon. Results will be compiled into a formal USGS SIM-series geologic map and described in a lunar mapping ‘handbook'. This guide will include evaluations and recommendations for digital data acquisition and basemap construction, their relative utility for unit identification, characterization, and mapping, and useful tools and tips for future lunar geologic mappers.