SHIELD-FIELD VOLCANISM ON PLANETS: THE SNAKE RIVER PLAIN AS THE TYPE EXAMPLE

Nearly a half century of solar system exploration shows that basaltic volcanism dominates the terrestrial planets, and includes the dark mare plains of the Moon, vast plains and volcanoes on Venus and Mars, and (probably) surfaces of Mercury, as well as Earth's sea floor. Modes of eruption and emplacement include vast flood eruptions of very fluid lavas, repeated effusive eruptions from central vents to forms shield volcanoes, local fissure-fed flows, and pyroclastic eruptions over a wide range of scales. The Snake River Plain of Idaho represents a distinctive style, termed Shield-Field Volcanism, which is typified by relatively small, low-profile, coalescing shield volcanoes erupted along local rift zones, combined with fissure-fed eruptions of long lava flows typically emplaced by lava tubes and channels. Most eruptions are effusive, but rare local explosive eruptions also occur. Shield-field volcanism is recognized in other places on Earth, as well as on Mars, Venus and (rarely) the Moon.