Spectral properties of Titan's impact craters imply chemical weathering of its surface

Catherine D. Neish (1) , Jason W. Barnes (2) , C. Sotin (3) , S. Mackenzie (2) , J. M. Soderblom (4) , Stéphane Le Mouélic (5) , R.L. Kirk (6) , B.W. Stiles (3) , M.J. Malaska (3) , Alice Le Gall (7, 8) , R.H. Brown (9) , K.H. Baines (3) , B. Buratti (3) , Roger N. Clark (10) , P.D. Nicholson (11)

1 Department of Physics and Space Sciences [FIT]
2 Department of Physics [Moscow,USA]
3 JPL - Jet Propulsion Laboratory
4 MIT - Massachusetts Institute of Technology
5 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
6 Astrogeology Science Center [Flagstaff]
7 ESTER - LATMOS
8 PLANETO - LATMOS
9 LPL - Lunar and Planetary Laboratory [Tucson]
10 US Geological Survey [Denver]
11 Department of Astronomy [Ithaca]

We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions.

Mots clés: Impact cratering; Erosion and weathering; Titan

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]

Catherine D. Neish, Jason W. Barnes, C. Sotin, S. Mackenzie, J. M. Soderblom, et al.. Spectral properties of Titan's impact craters imply chemical weathering of its surface. Geophysical Research Letters, 2015, 42 (10), pp.3746-3754. ⟨10.1002/2015GL063824⟩. ⟨insu-01154835⟩