GEOMORPHIC MAPPING IN MARGARITIFER TERRA, MARS: MTM -20022

The Margaritifer Terra region of Mars (0 – 30°S/ 0 – 45°W) contains numerous features that suggest a complex fluvial history. Although the major fluvial feature in the region is the Uzboi-Holden-Ladon-Margaritifer (UHLM) outflow system that flows northward from Argyre basin to Ares Vallis, much of southeastern Margaritifer Terra has been influenced by the Samara-Himera and Paraná-Loire Valles systems. These systems are two of the most well-integrated valley systems on Mars and drain approximately 540,000 km2. The Samara-Himera and Paraná-Loire systems merge just south of Margaritifer basin where they join the UHLM system. In addition to fluvial features, Margaritifer Terra has been influenced by cratering, several resurfacing events, and volcanic activity that likely continued into the Amazonian.

Mapping in MTM -20022 is part of a larger project to map portions of Margaritifer Terra at the 1:500,000 scale. This mapping involves using MOLA topography, MOC wide angle and narrow angle images, THEMIS infrared and visible images, and HiRISE images to identify boundaries between different geomorphic units in order to unravel the history of events that have shaped the surface of this complex region.

Within MTM -20022, Samara Valles and Himera Valles merge and flow northward to the west of Jones crater. One of the main goals of this mapping is to constrain the stratigraphic relationship between these valley systems and the impact that formed Jones crater. Whereas Viking images did not posses sufficient resolution to determine this relationship, newer data sets should lead to a determination of whether fluvial activity within the Samara-Himera system was still active when Jones formed. We will present the current state of this mapping and will focus on the fluvial-cratering relative timing, but we will also discuss other interesting features related to past fluvial activity. These features include valley networks on slopes adjacent to Himera and Samara Valles as well as abandoned meanders along portions of Samara-Himera Valles. The detailed mapping of these features allows us to form a better understanding of the timing of fluvial activity within this portion of Margaritifer Terra.