P12B-01
Alluvial Fans on Titan Reveal Atmosphere and Surface Interactions and Material Transport
Monday, 14 December 2015: 10:20
2007 (Moscone West)
Jani Radebaugh1, Dario Ventra2, Ralph D Lorenz3, Tom G Farr4, Randolph L Kirk5, Alexander Hayes6, Michael J Malaska7, Sam Birch6, Zac Yung-Chun Liu8, Jonathan I Lunine9, Jason W Barnes10, Alice Anne Le Gall11, Rosaly M C Lopes12, Ellen R Stofan13, Stephen D Wall12 and Philippe Paillou14, (1)Brigham Young University, Provo, UT, United States, (2)Utrecht University, Utrecht, Netherlands, (3)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (4)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (5)USGS Grand Canyon Monitoring and Research Center, Flagstaff, AZ, United States, (6)Cornell University, Department of Astronomy, Ithaca, NY, United States, (7)Organization Not Listed, Washington, DC, United States, (8)Arizona State University, Tempe, AZ, United States, (9)Cornell University, Ithaca, NY, United States, (10)University of Idaho, Moscow, ID, United States, (11)LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales, Paris Cedex 05, France, (12)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (13)NASA Headquarters, Washington, DC, United States, (14)University of Bordeaux 1, Talence, France
Abstract:
Alluvial fans, important depositional systems that record how sediment is stored and moved on planetary surfaces, are found on the surface of Titan, a body of significantly different materials and process rates than Earth. As seen by Cassini’s Synthetic Aperture Radar (SAR) images at 350 m resolution, fans on Titan are found globally and are variable in size, shape and relationship to adjacent landforms. Their morphologies and SAR characteristics, which reveal roughness, textural patterns and other material properties, show similarities with fans in Death Valley seen by SAR and indicate there are regions of high relative relief locally, in the Ganesa, Xanadu and equatorial mountain belt regions. The Leilah Fluctus fans near Ganesa are ~30 km x 15 km, similar to the largest Death Valley fans, and revealing mountainous topography adjacent to plains. Others have gentle slopes over hundreds of kilometers, as in the high southern latitude lakes regions or the Mezzoramia southern midlatitudes, where a fan system is 200 km x 150 km, similar to the Qarn Alam fan emerging into the Rub al Khali in Oman. Additionally, there is evidence for a range of particle sizes, from relatively coarse (~2 cm or more) to fine, revealing long-term duration and variability in erosion by methane rainfall and transport. Some features have morphologies consistent with proximality to high-relief source areas and highly ephemeral runoff, while others appear to draw larger catchment areas and are perhaps characterized by more prolonged episodes of flow. The presence of many fans indicates the longevity of rainfall and erosion in Titan’s surface processes and reveals that sediment transport and the precipitation that drives it are strongly episodic. Alluvial fans join rivers, lakes, eroded mountains, sand dunes and dissolution features in the list of surface morphologies derived from atmospheric and fluvial processes similar to those on Earth, strengthening comparisons between the two planetary bodies.
