MODELLING THE EMPLACEMENT OF A MARTIAN LAVA FLOW IN THE THARSIS MONTES REGION

Thus far there have been no sample return missions from Mars, which leaves a gap in our knowledge of the lavas emplaced there. This includes a lack of data for the composition, textures, and emplacement conditions. To characterize lava flow emplacement on Mars, a combination of remote sensing and modeling can be used. We revisit the use of FLOWGO to model flows emplaced on Mars (Harris et al., 2000; Rowland et al., 2004), with the combined use of image analysis and modeled data as inputs. Here, we examine a lava in the Tharsis Montes region of Mars that flowed 480 km northwest from the topographic saddle between Ascraeus Mons and Pavonis Mons with a channel width of 5,000m and a channel depth of 30m (Zimbleman et al. 1998). To model the emplacement of this flow using FLOWGO, we calculated the eruption temperature using MELTS (Ghiorso and Sack, 1995) using an analog composition of the basalt (McSween et al. 2003). Channel width, depth and length parameters are from results of Zimbleman, 1998. Rheologic parameters of the Tharsis Montes lava were based on other Martian flow models and environmental conditions specific to Mars such as density and parameters that impact cooling of the flow (Rowland et al., 2004; NASA, 2016). Proportions of crystals in the model were varied from 0-0.5% until the model produced a 458 km flow length. These parameters led to a model with an effusion rate of 18,568 m³/s and flow velocity of 0.124 m/s. This effusion rate and velocity are comparable to another Tharsis Montes region lava (Garry et al., 2007). Faster effusion rates and slower velocities than on Earth are expected given that Mars’ gravity (3.71 m/s²) is much lower than on Earth. With further refining of the combined use of MELTS and FLOWGO, we expect to further constrain parameters that cannot be directly observed or measured. Specifically, our goal is to use models of Martian flows to constrain down-channel crystallization and cooling parameters and improve our understanding of emplacement of these, and other extraterrestrial flows.