A 2013 study proposed that a number of craters within Arabia Terra, including Eden Patera, Euphrates Patera, Siloe Patera, and possibly Semeykin crater, Ismenia Patera, Oxus Patera and Oxus Cavus, represent calderas formed by massive explosive volcanic eruptions (supervolcanoes) of Late Noachian to Early Hesperian age. Termed plains-style caldera complexes, these very low relief volcanic features appear to be older than the large Hesperian-age shield volcanoes of Tharsis or Elysium. Eden Patera, for example, is an irregular, 55 by 85 km depression up to 1.8 km deep, surrounded by ridged basaltic plains. It contains three linked interior depressions, demarcated by arcuate scarps, that have terraces suggestive of lava lake drainage and faults suggestive of collapse. The features indicative of impact origin that would be expected in an impact crater of comparable diameter and depth are absent. The authors regard crustal thinning due to regional extension to be a more likely explanation for the origin of the volcanic activity than putative subduction. Rapid ascent of magma through the thin crust and a consequent relative absence of degassing may explain the more explosive eruption style associated with these paterae relative to that of the shield volcanoes. The eruptions would have contributed to the layered deposits of Arabia Terra, which are among the fine-grained deposits widespread in the equatorial regions of Mars. Total eruptive volumes of at least 4,600-7,200 km3 per caldera complex (over its history) were inferred.