The Long Sinuous Rille System in Northern Oceanus Procellarum and Its Relation to the Chang'e-5 Returned Samples

Abstract

China's Chang'e-5 (CE-5) mission recently returned samples from a young intermediate-Ti mare unit (Em4/P58, ∼1.5 Ga) in Northern Oceanus Procellarum. Rima Sharp, previously mapped as the longest lunar sinuous rille, is the most prominent volcanic feature associated with the landing region. Our analysis shows that Rima Sharp is not a single rille, but instead is composed of two separate rilles (Rima Sharp, originating from the North Vent, and Rima Mairan from the South Vent), meeting at ∼40.40°N, 48.38°W. Both vent have characteristics suggesting relatively low magma volatile contents. Rima Mairan and associated lavas (southeast of Em4/P58), embay and are slightly younger than Rima Sharp. Rille formation is largely influenced by pre-existing topography (earlier mare surface, proto-wrinkle ridges, highlands); rilles and deposits experienced post-formation deformation (wrinkle ridges, mare subsidence). CE-5 samples probably originate mainly from Rima Sharp's source vent, but may represent deposits from both rilles.