GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 215-2
Presentation Time: 1:55 PM

A RETROSPECTIVE ON MARS’ ALLUVIAL FANS (Invited Presentation)


HOWARD, Alan D., Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22904-4123, MOORE, Jeffrey M., NASA Ames Research Center, Space Science Division, MS-245-3, Moffett Field, CA 95129, PURDY, Sharon Wilson, Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, D. C, DC 20560, MORGAN, Alexander M., Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, 600 Independence Ave SW, Washington, DC 20560 and KITE, Edwin S., Dept. Geophysical Sciences, University of Chicago, 5734 S. Ellis Avenue Chicago, Chicago, IL 60637

In a classic planetary paper, Jeff Moore identified multiple large alluvial fans in the first high resolution post-Viking images. These crater-hosted fans, up to 40 km in length, rival the largest terrestrial examples. Issues raised in that paper are still uncertain after more than 15 years and much better image resolution and topography. Why do only some craters host fans? Why are fans sourced from localized source basins? What was the climatic and hydrologic regime that favored fan development? Why, as recent studies have demonstrated, did most alluvial fans form well after the end-of-Noachian pulse of crater degradation and valley network formation? We review these issues in the context of new studies demonstrating a complex history of alluvial fan development, including intercalation of glacial, lacustrine and mantling processes with fan activity.