pluton

pluton, body of intrusive igneous rock the size, composition, shape, or exact type of which is in doubt; when such characteristics are known, more limiting terms can be used. Thus, plutons include dikes, laccoliths, batholiths, sills, and other forms of intrusions. Most plutons are thought to be the result of igneous activity in which a magma is involved; the controversial origin of some large granitic bodies, however, requires that metasomatic processes or granitization be included when discussing many plutons.