EVALUATING A POTENTIAL VOLCANO ON THE RIM OF JEZERO CRATER, MARS

On the southeast rim of Jezero crater is a feature that stands up to ~2 km high above the surrounding area, with an irregularly shaped crater on its summit and the lowest thermal inertia of the Jezero region. While several studies and recently NASA’s Perseverance rover have focused on understanding the likely volcanic origin of the Jezero crater floor unit, little has been done to characterize this largest and closest seemingly volcanic feature. Using multiple data sets such as the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), the High-Resolution Imaging Experiment (HiRISE), the Context Camera (CTX), the Thermal Emission Imaging System (THEMIS) and the Mars Orbiter Laser Altimeter (MOLA), we study the possibility of this mountain having a volcanic origin, which could have important implications when interpreting Perseverance’s findings.

Even with limited CRISM coverage of the mountain and despite its prior interpretation as dust-covered, we observed diverse mineralogy. Some regions were spectrally dominated by olivine or pyroxene, and localized Mg/Fe-smectite clay exposures were also detected. To investigate how this mountain compares to other Martian volcanoes, we used MOLA data to create topographic profiles and to measure geomorphic properties (slope, elevation, diameter, elevation/diameter ratio, caldera diameter, caldera depth, and caldera depth/diameter ratio) for comparison with eight other Martian volcanoes. Additionally, we measured the average thermal inertia of each of these volcanoes for which THEMIS images with an image rating higher than four were available.

While inferring a definite origin may not be possible from orbit, several lines of evidence are consistent with a volcanic interpretation. The near centralized summit crater, the slopes consistent with stratovolcanoes, the lack of distinguishable lava flows, the relatively smooth caldera interior and lower thermal inertia are all consistent with explosive volcanism. Igneous minerals olivine and pyroxene are present, and clay minerals could imply ancient formation of easily alterable (fine-grained, glassy) material, as recently reported on other ancient Martian stratovolcanoes.