Sheet intrusion

A sheet intrusion, or tabular intrusion, is a planar sheet of roughly the same thickness, that forms inside a pre-existing rock.

[1] When it cuts into another unlayered mass, or across layers, it is called a dike.

An igneous sheet intrusion is formed where a mass of molten magma takes advantage of a pre-existing linear feature in a host rock, such as a long rupture or fault, and forces its way into these spaces.

They are among the most extensive igneous features on Earth,[citation needed] in the form of dikes, laccoliths, cone sheets and sills.

When limestone or other precipitate forms in a fault space, it is a sedimentary sheet intrusion.