It is generally accepted that volcanic caldera formation takes place when supporting material is removed from below. There is much field and laboratory evidence to suggest that this material is removed via magma loss from a shallow reservoir to feed an eruption or intrusion (e.g. [1, 2 and 3]). There is nothing to suggest however that the supporting material must be magma.

Calculations show that if the ice held within a cryosphere were melted, by a hot magmatic intrusion, compaction of the remaining rock could take place and cause collapse of a coherent overlying block, analogous to conventional caldera collapse. Furthermore this process is likely to occur at a variety of smaller scales in a similar fashion to kettle-hole formation on Earth.

Hecates Tholus, Mars (31.73° N 150° E) has many pits, channels and depressions of ambiguous origin in addition to well-studied fluvial channels (Fig 1). We explore the hypothesis that many of these features were formed by this ice-melting mechanism and that such melting could have influenced the formation of one or more of the calderas themselves.