Geomorphological analysis and Digital Elevation Model of Monad Regio, Triton

Introduction The complex geomorphology of Triton reflects its geological history [1]. The morphological heterogeneity on small scale has led to discerning three main complexes: cantaloupe terrains, equatorial plains, and south polar cap terrains. We analyse an area located in the east equatorial zone of Triton called Monad Regio (centred at 37°N, 2°E), characterized by the presence of walled plains. We produced a new geological map and a DEM (Digital Elevation Model) to recognize the main terrains and features in the study area. We used Voyager 2 imagery named c1139533 (600 m/px) [2], properly calibrated, filtered, and georeferenced using the Integrated Software for Imagers and Spectrometers (ISIS4) [3]. Results and conclusions We mapped the different geological units and main features according to differences in surface morphology (Fig.1). Terraced terrain covers most of the studied area. It shows a chaotic pattern characterized by several terraces, some of which lay in a parallel arrangement around some of the large depressions. These basins have areas ranging from 1300 to 2050 km2, and their degree of alteration is variable, with the features inferred to be more recent showing an inner minor basin within the main one. The most altered basins appear smoother, featureless, and shallower. Sizes and excavation depths estimated using DEM data of the observed basin features appear to be relatively homogeneous, which leads us to exclude an impact related origin. We argue that the origin of these depressions is linked to processes analogue to those described in the formation of terrestrial maar craters and possible explosion craters discussed on Titan [4]. Alternatively, diapirism may also explain the origin of such features. Further analysis could help to understand the nature and related processes that originated these basins. Acknowledgements G.M., C.C. and D.S. acknowledge support from the Italian Space Agency (2020-13-HH.0). References [1] Basilevsky A.T. et al.,1992. Adv. Space Res.,12(11), 123-132. [2] Smith, B. A., et al. (1989), Science, 246 (4936), 1422-1449. [3] Houck J.C. and DeNicola L.A. (2000) Astronomical Data Analysis Software and Systems IX, ASP Conference Series,216. [4] Mitri G., et al. (2019), Nature Geoscience, 12, 791,796.