18-2 Sedna Planitia, Venus: A Geomorphic Evaluation and Implications for Lithospheric Thickness

Session: Surface Processes Across the Solar System

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Abstract:

Sedna Planitia is a large area of low-lying regional plains material found to the south of Ishtar Terra, the east of Beta Regio, and north of Sif and Gula Mons. The majority of Sedna Planitia is covered by two map quadrangles: V-18 Lachesis Tessera (300^o-330^oE, 25^o-50^oN) and V-19 Sedna Planitia (330^o-360^oE, 25^o-50^oN). The V-18 quadrangle covers the transition zone from a major area of uplift to the west (Beta Regio) to a major area of low-lying plains (Sedna Planitia), making it important to the overall investigation of the evolution of the surface and lithosphere of Venus. Similarly, the V-19 quadrangle covers the transition zone from the Eistla Regio uplift to the south and Ishtar Terra in the north, divided by Sedna Planitia.

While it has been generally accepted that Venus has a thick stagnant lithosphere, much like Mars and Mercury, recent studies have suggested that regions of Venus could have thinner lithosphere. The authors of the global map of crustal and lithospheric thickness on Venus found that the lithosphere under the plains was much more variable than previously thought, and might even still be undergoing active deformation. They suggested that their results “highlight the need to examine the relationship between small-scale (<1000 km) features and lithospheric properties to fully interpret the geologic history” of Venus. We suggest that determining the thickness of the Venus lithosphere in Sedna Planitia could have important implications towards our understanding of the history and development of the interior of Venus and how it differs from the other terrestrial planets.

To better understand the geology of Sedna Planitia, we are preparing geologic maps of the region. A 1:5M quadrangle map of V-18 is already complete; the V-19 quadrangle map utilizes the map units defined for V-18, and continues contacts across the boundary between the two quadrangles. To shed some light on which geomorphic features might represent different lithospheric thicknesses, we are also performing higher resolution 1:500k mapping of the tesserae, volcanoes, and corona.

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