patera

A broad, shallow dish used for drinking, primarily in ritual contexts such as libations.

A circular ornament, resembling a dish, often worked in relief on friezes etc.

The caldera or crater (dish-shaped depression) atop a volcano, especially an extraterrestrial one; also used in the names of extraterrestrial volcanoes which have such a caldera.

What caused the transitions from explosive to effusive volcanism in the Circum-Hellas Volcanic Province generally and during the eruptive lifetimes of individual highland patera volcanoes?

Note that the eroded plains materials to the right of the patera show no signs of individual lava flows.