DIKE (GEOLOGY)

A 'dike' or 'dyke' in geology refers to an intrusive igneous body. The thickness is usually much smaller than the other two dimensions. Thickness can vary from sub-centimeter scale to many meters in thickness and the lateral dimensions can extend over many kilometers. A dike is an intrusion into a cross-cutting fissure, meaning a dike cuts across other pre-existing layers or bodies of rock, this means that a dike is always younger than the rocks that contain it. Dikes are usually high angle to near vertical in orientation, but subsequent tectonic deformation may rotate the sequence of strata through which the dike lies so that the latter becomes horizontal. Near horizontal or conformable intrusions along bedding planes between strata are called intrusive sills. The world's largest dike swarm is the Mackenzie dyke swarm in the Northwest Territories, Canada.^[1]
Dikes often form as either radial or concentric swarms around plutonic intrusives or around volcanic necks or feeder vents in volcanic cones. These are known as "Ring Dike"s.
Dikes can vary in texture and composition from diabase or basaltic to granitic or rhyolitic. Pegmatite dikes are extremely coarsely crystalline granitic rocks often associated with late stage granite intrusions or metamorphic segregations. Aplite dikes are fine grained or sugary textured intrusives of granitic composition.

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See also

References

See also

★ Batholith

★ Ring Dike

★ Fissure vent

★ Laccolith

★ Runamo, formerly interpreted as a runic inscription.

★ Sill

References

1. Supressing Varying Directional Trends Retrieved on 2007-07-28