Chapter 3 Volcanism Flashcards
Volcanism definition
The surface expression of melting processes occurring within a planetary body.
It describes associated with the transfer of volatiles, magma, and suspended crystallised materials from the interior to the surface, and if present, the atmosphere.
Most obviously demonstrated by the presence of volcanoes that erupt laves, produce ash and gas clouds.
Effusive volcanism
Smaller eruptions releasing more lava than gas, less explosive and create lava flows.
Explosive volcanism
Characterised by the production of eruption columns and pyroclastic flows. Created by more viscous (thick) lavas with more trapped gas bubbles.
Where can volcanism be found?
Volcanism affects the surface of all the larger silicate bodies in the Solar system, although most do not appear to be currently volcanically active.
Io ( a moon of Jupiter) is however, and has volcanoes randomly scattered across its surface.
What is the most widespread volcanism.
Effusive volcanism of basaltic lavas is the most widespread manifestation of volcanism. it is the result of partially melted mantle material derived from chondrite composition, typical of terrestrial planets and smaller bodies.
Basaltic magmatism on earth
Basaltic lavas cover 70% of earths surface ( and large portions of the moon, mercury, Venus and mars).
In earths case widespread basaltic magmatism that generates ocean floor and continental flood basalt provinces is largely the result of partial meltting due to decompression in the upper mantle.
Cryovolcanism
Partial melting of ices leads to volcanism on icy body’s. The eruption products of icy volcanism are subject to the same physical processes regarding the migration of magma, volatile release and eruption dynamics that occur in silicate bodies.
Places with active explosive cryovolcanism
Enceladus, triton and Europa
Recent effusive volcanism locations
Titan and Pluto
Ancient effusive cryovolcanism locations
Ariel, Miranda, triton and Sharon.
What causes partial melting on earth?
Decompression mantle is a common form of partial melting where hot dense material travels up, if it can maintain sufficient heat, then the mantle will start to melt as there is no longer enough pressure to keep it solid. This can occur on both silicate and icy bodies.
What heats Io ( moon of Jupiter)
Io’s volcanism is filed by tidal heating caused by Jupiters gravity. Its dominant volatile is probably sulfar dioxide, not water. Its lava is erupted at extremely high temperatures suggesting silicate magmas of komatiitic composition.
What creates different eruptions
Differences in gravity, atmosphere, surface temperature and magmatic composition.
Larger bodies create magma with greater buoyancy, so it will rise with more energy.
If no atmosphere is present no eruption column can form so gas escapes into space, whilst ejected fragments follow ballistic trajectory. An atmosphere such as earths creates column convection which carries ash and gas up in a column that collapses once it looses energy creating pyroclastic flow.
