Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8134834 | Icarus | 2016 | 17 Pages |
Abstract
Lunar concentric craters are a unique class of impact craters because the interior of the craters contains a concentric ridge, but their formation mechanism is unknown. In order to determine the origin of concentric craters, we examined multiple working hypotheses, which include eight impact-related and endogenic processes. We analyzed data sets that originated from instruments onboard Clementine, Kaguya, and the Lunar Reconnaissance Orbiter to characterize the morphology, spatial distribution, composition, and absolute model ages of 114 concentric craters. Concentric craters contain five key properties: (1) a concentric ridge, (2) anomalously shallow floors, (3) their occurrence is concentrated near mare margins and in mare pond regions (4) the concentric ridge composition is similar to the surrounding area and (5) concentric crater ages are Eratosthenian and older. These five key properties served as constraints for testing impact-related and endogenic mechanisms of formation. We find that most impact-related hypotheses cannot explain the spatial and age distribution of concentric craters. As for endogenic hypotheses, we deduce that igneous intrusions are the likely mechanism that formed concentric craters because of the close relationship between concentric craters and floor-fractured craters and the concentration of both features near mare-highland boundaries and in mare ponds. Furthermore, we observe that floor-fractured craters are common at crater diameters >Â 15Â km, whereas concentric craters are common at crater diameters <Â 15Â km. We suggest that igneous intrusions underneath small craters (<15Â km) are likely to form concentric craters, whereas intrusions under large craters (>15Â km) produce floor-fractured craters.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Space and Planetary Science
Authors
David Trang, Jeffrey J. Gillis-Davis, B. Ray Hawke,