Geology and composition of the Orientale Basin impact melt sheet
Article first published online: 8 JAN 2014
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Planets
Volume 119, Issue 1, pages 19–29, January 2014
How to Cite
2014), Geology and composition of the Orientale Basin impact melt sheet, J. Geophys. Res. Planets, 119, 19–29, doi:10.1002/2013JE004521., , and (
- Issue published online: 28 FEB 2014
- Article first published online: 8 JAN 2014
- Accepted manuscript online: 27 NOV 2013 06:24PM EST
- Manuscript Accepted: 21 NOV 2013
- Manuscript Revised: 1 NOV 2013
- Manuscript Received: 5 SEP 2013
- impact melt;
 The Orientale Basin is one of the largest (930 km diameter) and youngest (~3.8 Ga) impact craters on the Moon. As the basin is only partly flooded by mare lava, its floor materials expose a major portion of the basin impact melt sheet, which some previous work has suggested might have undergone igneous differentiation. To test this idea, we remapped the geology of the Orientale Basin using images and topography from the Lunar Reconnaissance Orbiter, mineralogical information from the Chandrayaan-1 Moon Mineralogy Mapper, and elemental concentration maps from Clementine multispectral imaging and Lunar Prospector gamma ray data. The Maunder Formation (impact melt sheet of the basin) is uniform in chemical composition (equivalent to “anorthositic norite”) in at least the upper 2 km of the deposit. The deepest sampling of the basin melt sheet (maximum depths of ~3–5 km by the crater Maunder, 55 km in diameter) shows a variety of lithologies, but these rock types (anorthosite, anorthositic norite melt rocks, mare basalt, and gabbro) are not those predicted by the differentiation model. We conclude that no differentiation of the Orientale Basin melt sheet has occurred and that such a process is not evident from new remote sensing data for the Moon or in the Apollo lunar samples.