Geomorphic study of caldera features on Mars with the help of Earth analogues
Authors: Chu Yin Yau , Michalski Joseph R. 
Published: February 2023

Geomorphological analogues provide a valuable perspective for understanding planetary volcanic structures, landforms, and processes. Arabia Terra, Mars contains numerous collapse structures that are somewhat controversially interpreted as calderas. This work aims to use planetary analogues to shed further light on possible martian caldera collapse and volcanic processes.The project had a focus on a population of underrecognized ancient volcanic constructs that associated with explosive and effusive volcanism, termed &#8220;plains-style caldera complexes&#8221; (Michalski and Bleacher, 2013), that are present within the Arabia Terra and perhaps across the Noachian-Hesperian crust on Mars. These features are characterised by deep crustal collapse, presence of flow deposits, potential pyroclastic materials, and more importantly, without a pronounced central edifice. Notable examples of the plains-style caldera complexes includes: Eden Patera (33.5&#176;N, 348.8&#176;E), type-locality of the plains-style caldera complexes; Siloe Patera (35.3&#176;N, 6.55&#176;E), which presents two overlapping classic piston-type caldera collapse; and Hiddekel Cavus (29.4&#176;N, 16.2&#176;E), a narrow, cone-shaped depression with extremely high depth/diameter ratio. In this project, besides working on Martian satellite imagery and topographic data, terrestrial analogue study was also a useful tool when analysing caldera floor geomorphology at Eden Patera.&#160;The Hawaiian volcanoes have previously been used as analogues for certain volcanic processes on Mars (Mouginis-Mark et al., 2007; Hauber et al., 2009). Though the Hawaiian volcanoes formed through different volcanic styles than the plains style caldera complexes, they nonetheless provide insight into key processes. At K&#299;lauea volcano, Hawai&#699;i, the caldera collapse and volcanic deposits were associated with Hawaiian-style effusive eruption of basaltic lava, accompanied by minor explosive eruptions (Stovall et al., 2011; Patrick et al., 2020). K&#299;lauea Iki and Halema&#699;uma&#699;u, the pit craters of K&#299;lauea, were considered as potential terrestrial analogue for (1) the &#8220;black ledge&#8221; formation (chilled lava lake margin feature) and (2) isolated &#8220;islands&#8221; of pyroclastic materials on the caldera floor at the Eden Patera, and both features are important evidence supporting a volcanic story, as well as both effusive and explosive activities of the Eden Patera caldera complex.Nonetheless, potential analogue for caldera collapse mechanism was once again identified at K&#299;lauea Halema&#699;uma&#699;ufor an unnamed cavus of possible volcanic origin within the mid-Noachian to Hesperian plain of Xanthe Terra, Mars (Tanaka et al., 2014). Both the Hawaiian pit crater and Martian cavus are deep depressions with steep scarps, overlying a region of extensive concentric faults and fractured crust, making K&#299;lauea a good candidate for future analysis as a terrestrial analogue for caldera features of the plains-style caldera complexes on Mars.