A SURVEY OF THE THARSIS VOLCANIC PLAINS: MAPPING LAVA CHANNELS AND TUBES ON MARS

The Tharsis Montes are colossal volcanoes on Mars that have long been of scientific interest since the Mariner 9 mission, on which numerous studies have been performed. No detailed analysis had been done of the surrounding volcanic plains, however, as they were thought to be dusty, featureless wastelands. With the onset of higher resolution cameras aboard orbiters like MRO, better images have since been taken that reveal a plethora of intriguing features like small volcanoes and cones, giant fissures, and a network of lava channels and tubes. This study endeavored to map these channelized lava flows, thereby adding to a database of known eruption features, unraveling the relationship between the volcanic plains and the large Montes, and better characterizing the long history of volcanism at Tharsis. The focus area for this study was confined to the volcanic plains south east of Pavonis and Ascraeus Mons, and north of Noctis Labyrinthus, resulting in an area of about 40,000 km². The channels were mapped in the GIS software ArcMap, using MRO’s 6 meter-per-pixel Context Camera (CTX) images overlaid on a MOLA basemap. The main product of this study was a comprehensive map outlining the location and distribution of over 1200 channels. The channels were divided into seven types based on their unique morphological characteristics. These types include 1) sinuous rilles, 2) leveed channels, 3) pit chains, 4) wide and blocky channels, 5) thin ridges, 6) plateaued channels, and 7) irregular channels. An analysis of the channels’ lengths showed high variability, with channels ranging in length from 1 m to 250 km (with an average length of 11 km). Additionally, for a sample of 25 of each channel type (175 total), a statistical analysis of width, sinuosity, and slope were performed. The map and statistical data may be used to calculate effusion rate and lava fluxes, help constrain the extent and timescale of water on Mars within Tharsis (many channels exhibit rootless cones and complex branching), or even reveal formation patterns and locations of lava tubes, which are of interest as possible shelters for future human exploration. Ultimately, this data will be used to better understand how and where channels formed within the Tharsis region and on Mars in general.