THE LEVANTINE JUBA DEPRESSIONS AS TERRESTRIAL ANALOGS FOR PLANETARY PITS

Geological depressions, such as pits, abound on the surface of Mars and other planetary bodies. Despite their ubiquity, the origin of many depressions remains poorly constrained, partially due to the current paucity of suitable terrestrial analogs. Here, we present a new terrestrial analog site with geological depressions that morphologically resemble Martian bowl-shaped pits. The analog site consists of tens of geological depressions (locally named “juba”), which occur within a Pleistocene basaltic plateau that overlies Meso-Cenozoic carbonates. This plateau is located at the northwestern margin of the Levantine volcanic field of Harrat Ash-Shaam along the Dead Sea Transform. We constrained plausible formation mechanisms for the terrestrial juba depressions by a combination of detailed field mapping and morphometric analyses of a 0.25 m/pixel LiDAR-based digital terrain model (DTM). We show that variable magnitudes of slope asymmetry between the north- and south-facing walls within the juba depressions together with different degrees of sediment infilling provide effective proxies for the geomorphic maturity of these landforms, which in turn indicates asynchronous formation of the juba depressions after the Pleistocene emplacement of the Harrrat Ash-Shaam basalts in the study area. Our findings preclude phreatomagmatic explosions as the juba depression formation mechanism, indicating instead that these pits formed by collapse into missing subsurface volume. We more broadly propose that the morphometric analyses developed in this study can be extended to constrain the formation mechanisms of similar pit features on Mars and other planetary bodies.