ISS Chapter 3 Flashcards
What is the precise definition of volcanism?
The transfer of molten materials, associated volatiles and any suspended crystalline material, from the interior of a planetary body to its surface.
What are the two prerequisites for volcanic eruptions?
A process that causes melting.
A material that can be melted.
What are the two types of volcanic eruptions?
Quiescent
Explosive
What is the key component of a quiescent eruption?
Slow flows of lava.
What is the key component of explosive eruptions?
Huge columns of ash and dust and a violent eruption.
What is decompression melting?
When a material moves from an area of greater pressure to a lower pressure area, the material melts.
What is hydration-induced melting?
When water or other volatiles are introduced to the mantle, for example, they change the composition of the surrounding material and lower the melting temperature.
What are volcanic arcs?
Arcs of volcanoes produced along subduction areas as water is introduced into the mantle below.
What are mid-ocean ridge basalts?
Basalt melts that are produced by the upwelling of asthenosphere material at mid-ocean ridges.
What are constructive plate boundaries?
Boundaries where plates spread apart and new crust is created.
What are destructive plate boundaries?
Boundaries where one plate is forced beneath another and recycled into the mantle.
What is the precise definition of partial melting?
A parent material doesn’t fully melt as its constituent parts have different melting points. The resulting melt has a chemical composition that is different to the parent.
Where does partial melting typically begin within the structure of a rock?
At the interstices, the meeting point between three crystals.
What is the composition of the most common volcanic material amongst the terrestrial planets?
A broadly basaltic composition.
In the context of melting, what are incompatible elements?
Elements that will preferentially move to melt material rather than stay within the source rock.
