Dikes often form as either radial or concentric swarms around plutonic intrusives, volcanic necks or feeder vents in volcanic cones.
Dikes can vary in texture and their composition can range from diabase or basaltic to granitic or rhyolitic, but on a global perspective the basaltic composition prevails, manifesting ascent of vast volumes of mantle-derived magmas through fractured lithosphere throughout Earth history.