Photogeology: Part D: Descartes highlands: possible analogs around the Orientale Basin

The Descartes highlands are adjacent to the terra plain on which the Apollo 16 lunar module landed (fig. 29-13). A variety of volcanic origins was proposed for the highlands before the mission (refs. 29-4, 29-21, and 29-35 to 29-37), but the returned samples of the area consist almost exclusively of nonvolcanic breccias. The breccias obtained from Stone Mountain have not been identified conclusively as sample materials of the Descartes Mountains (ref. 29-35). A volcanic origin is thus not yet precluded (sec. 6 of this report), but a review of possible impact-related origins seems to be appropriate. The orbital photography acquired during the Apollo 16 mission provides excellent imagery on which geomorphic interpretations may be based. No obvious local crater is a plausible source of the material, but there may be a relation to either the Nectaris or Imbrium Basin. The less degraded Orientale Basin (fig. 29-24) provides a model by which these comparisons can be made (part F of this section).