Magmatism

Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks.

Only the volcanic parts of modern arcs are exposed at the surface and the understanding of the underlying magma chambers relies on geophysical methods.

Continental collisions are accompanied by major crustal thickening, leading to heating and anatexis within the crust, generally in the form of peraluminous granitic intrusions.

Post-collisional magmatism is a result of decompression melting associated with isostatic rebound and possible extensional collapse of the thickened crust formed during the collision.

Over short geological timescales the hotspots appear to be fixed relative to one another, forming a reference frame against which plate motions can be measured.

Many continental rift zones are associated with magmatism due to upwelling of the asthenosphere as the lithosphere is thinned, which leads to decompression melting.

Large igneous provinces (LIPs) are defined as "mainly mafic (+ ultramafic) magmatic provinces with an areal extent >0.1 Mkm2 and igneous volume >0.1Mkm3, that have intraplate characteristics, and are emplaced in a short duration pulse or multiple pulses (less than 1–5 Ma) with a maximum duration of