Topographic Constraints on the Evolution and Connectivity of Titan's Lacustrine Basins

• Published in: Geophysical research letters 2017-12, Vol.44 (23), p.11,745-11,753
• Main Authors: Hayes, A. G., Birch, S. P. D., Dietrich, W. E., Howard, A. D., Kirk, R. L., Poggiali, V., Mastrogiuseppe, M., Michaelides, R. J., Corlies, P. M., Moore, J. M., Malaska, M. J., Mitchell, K. L., Lorenz, R. D., Wood, C. A.
• Format: Article
• Language: English
• Subjects: Altimetry; Banks (topography); Basins; Connectivity; Curvature; Dissolution; Dissolving; Drainage basins; Earth; Earth surface; equipotential; Erosion; Evolution; Geologic depressions; geomorphology; Karst; Lake basins; Lakes; lakes and seas; Measuring instruments; Ocean basins; Oceans; polar; Quantitative analysis; Radar; Rims; SAR (radar); Saturn satellites; Sea level; Slope; Synthetic aperture radar; Titan; Topography; Topography (geology); Watersheds
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2017GL075468

The topography provided by altimetry, synthetic aperture radar‐topography, and stereo radargrammetry has opened new doors for Titan research by allowing for quantitative analysis of morphologic form. Using altimetry measurements, we show that Titan's Maria are consistent with an equipotential surface but that several filled lakes are found to be hundreds of meters above this sea level, suggesting that they exist in isolated or perched basins. Within a given drainage basin, empty lake floors are typically higher than the liquid elevation of nearby lakes/seas, suggesting local subsurface connectivity. The majority of Titan's lakes reside in topographically closed, sharp‐edged depressions whose planform curvature suggests lateral expansion through uniform scarp retreat. Many, but not all, empty lake basins exhibit flat floors and hectometer‐scale raised rims that present a challenge to formation models. We conclude that dissolution erosion can best match the observed constraints but that challenges remain in the interpretation of formation processes and materials. Plain Language Summary From a combination of topographic techniques, we show that the liquid elevations of Titan's seas are consistent with an equipotential surface (similar to Earth's oceans). The same measurements show that Titan's small lakes can be found several hundreds of meters above the sea level, suggesting that they are potentially isolated from the seas. Within a given watershed, however, nearby lakes show evidence for local connectivity. Using the same topographic data set, we examine the topographic profile of Titan's filled and empty lake depressions. The depressions have flat floors and hundred‐meter scale raised rims that present a challenge to understanding their formation. We conclude that dissolution erosion (e.g., karst on Earth) can best match the observed constraints but that challenges still exist in the interpretation of formation processes and materials. Key Points Titan's seas are consistent with an equipotential surface The liquid elevation of Titan's lakes can be found hundreds of meters above the seas Lakes reside in topographically closed, sharp‐edged depressions. Many have raised rims that are hard to reconcile with formation models