Morphology and Distribution of Volcanic Vents in the Orientale Basin from Chandrayaan-1 Moon Mineralogy

Introduction and Background: One of the most fundamental questions in the geological and thermal evolution of the Moon is the nature and history of mantle melting and its relationship to the formation and evolution of lunar multi-ringed basins. Mare volcanic deposits provide evidence for the nature, magnitude and composition of mantle melting as a function of space and time [1]. Many argue that mantle partial melts are derived from depths well below the influence of multi-ringed basin impact events [1], while others postulate that the formation of these basins can cause mantle perturbations that are more directly linked to the generation ascent and eruption of mare basalts [2,3]. In any case, longer-term basin evolution will considerably influence the state and orientation of stress in the litho-sphere, and the location of mare volcanic vents in basins as a function of time [4]. Thus, the location, nature and ages of volcanic vents and deposits in relation to multi-ringed impact basins provides evidence for the role that these basins played in the generation of vol-canism or in the influence of the basins on surface volcanic eruption and deposit concentration. Unfortunately, most lunar multi-ringed impact basins have been eroded by impacts or filled with lunar mare deposits [5-8], with estimates of the thickness of mare fill extending up to more than six km in the central part of some basins [9-11]. The interior of most basins (e.g., Crisium, Serenitatis, Imbrium, Humorum) are almost completely covered and obscured. Although much is known about the lava filling of multi-ringed basins, and particularly the most recent deposits [5-8], little is known about initial stages of mare volcanism and its relationship to the impact event. One multi-ringed basin, Orientale, offers substantial clues to the relationships of basin interiors and mare basalt volcanism. The Orientale basin (~920 km in diameter), the youngest and most well preserved multi-ringed basin on the Moon, displays remarkably fresh examples of the multiple rings that are the hallmark of these types of structures [12-14]. The Cordillera Mountain ring (CR), an inward facing mountain scarp ~920 km in diameter, defines the basin itself. The next inward ring, the Outer Rook Mountain ring (OR), is characterized by a ring of major interconnected massifs ~620 km in diameter. The next innermost ring, the Inner Rook Mountain ring (IR) ~480 km in diameter, consists of isolated mountain peaks that resemble central peaks and central peak rings in smaller …