Rejuvenated Lunar Geologic Mapping: Overview and Copernicus Quadrangle Status

The geology of the lunar surface has not been methodically mapped at a consistent scale since the Apollo era. To examine the feasibility and success of rejuvenated efforts, a pilot lunar geologic mapping project is underway with funding from PG&G. Supported by newly available and registered digital data products, we are concentrating on a quadrangle at 1:2.5M scale centered at -22.5 E longitude, extending from 0 to -45 E and from 0 to 30 N. Importantly, this region contains surface type-localities for the most recent lunar stratigraphic systems: materials of Copernicus and Eratosthenes craters. The selected quadrangle includes Lower Imbrian basin-related materials, Upper Imbrian mare basalts and pyroclastic deposits, Eratosthenian mare basalts and crater materials, and Copernican impact and related deposits. The mapping approach is iterative, with initial map drafts focusing on characterization of map units and contact and stratigraphic relationships using topographic models and Lunar Orbiter IV regional photomosaics. These results are blended with Clementine UVVIS and NIR single and mixed-band images and well as modeled element and mineral distributions to assist in delineating lateral chemical variations both in mare materials and exhumed and redistributed basement rocks. We hope the results of pilot map efforts will (1) underscore the validity of a rejuvenated lunar geologic mapping program, (2) illuminate significant caveats of applying classical mapping procedures to the lunar surface, (3) clarify and standardize interpretive datasets in lunar mapping, and (4) promote the consistent distribution of lunar data products from the USGS.