The "jubot" depressions of the north-west Harrat Ash-Shaam volcanic field as terrestrial analogs for planetary pits.

The nature of many pits on the surface of Mars and other planetary bodies remains poorly constrained due to the paucity of terrestrial analogs with similar characteristics. Collapse pit craters on the flanks of the Kīlauea volcano in Hawaii are typically considered to be the closest analogs. However, the stratigraphy and formation mechanism of the Kīlauea pit craters may not apply to many of the martian pits. Here, we present an additional terrestrial analog for planetary pits. A series of depressions, locally named "jubot", are situated on a basaltic plateau on the north west margins of the Levantine volcanic field of Harrat Ash-Shaam, in the vicinity of several Pleistocene cinder cones. The moderately sloping basaltic plateau is underlain by Mesozoic to Cenozoic sedimentary rocks, comprised mostly of carbonates. The structure of this underlying stratigraphy records past local tectonic stress fields. To constrain the formation mechanism of the jubot we acquired high resolution (0.25 m/pixel) digital elevation models (DEMs) from airborne LiDAR of the jubot field, as well as cm-scale scan of a bell-shaped pit with an interior hidden from aerial view, using ground-based LiDAR. From the DEMs, we extracted morphometric and structural parameters of the jubot and their surroundings, and their spatial distribution. To distinguish between possible formation mechanisms of the jubot, we explored correlations between these measurements and other tectonic, volcanic and morphological structures in the area. Our findings preclude formation of the Jubot by meteorite impacts and phreatomagmatic explosions, and appear to be consistent with formation by collapse into subsurface voids. Some surface structures suggest the voids may have originated from volcanic or tectonic activity, but hints of a spatial correlation between the jubot locations and karst-forming carbonate units may point to a karstic origin for the voids. We are currently investigating these two possibilities with a combination of detailed field mapping and tomographic methods. The possibility that martian pits may constrain either volcano-tectonic or hydrological subsurface processes motivates the development and study of terrestrial analogs where such a linkage between the surface-subsurface can be tested in the field.