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Sinuous Volcanic Channels on Tharsis Montes (Mars) Rift Aprons

Kijani Derenoncourt, Sean Peters

Abstract

Lava channels 100s of kilometers in length, observed on Venus, the Moon, and Mars, display morphologies suggestive of thermo-mechanical erosion. Exotic lava compositions and high effusion rates have been proposed to explain these features. On Mars, the spatial distribution, morphology, and emplacement conditions are key to understanding the planet's interior and surface evolution. For this study, we focus on sinuous channels on the Tharsis Montes (Arsia, Pavonis, and Ascreaus) rift aprons, landforms constructed by effusive volcanic deposits formed after the shield-building phase of the Tharsis Montes concluded. The aprons represent an understudied region with relatively young deposits. We delineated rift apron subregions using previous literature (e.g. Plescia 2004) and changes in slope and flow direction. An initial survey conducted using THEMIS IR and CTX data located 350+ features. We ranked the features using a confidence scale: 1 = very unlikely volcanic and 5 = very likely volcanic, based on morphology and regional context with ~100 volcanic channels confirmed. On the southern rift apron of Ascraeus Mons, extending from an elevation of ~5.6 - 8.3 km, we have identified 30 volcanic channels. Channels range in length from ~7.5 - 240 km with a mean length of 50 km and a median length of 26 km. Regional slopes range from ~0.3 - 2°. This suggests that long-lived effusive eruptions were part of the later evolution of the large shield volcanoes on Mars. Our work is ongoing as we continue to characterize and quantify channel morphology.