Lithodemic terms are necessary for rocks that cannot be successfully accommodated in the lithostratigraphical scheme. They generally apply to intrusive, highly deformed and/or highly metamorphosed and genetically mixed assemblages of rocks. Only three ranks are formally defined -- supersuite, suite and lithodeme; other ranks are used informally. Terms used for igneous lithodemes include central complex, pluton, dyke-swarm, sill-complex.
Some possible lithodemic relationships are shown schematically below, with informal terms italicised.
|Supersuite A||Suite D||
|Pluton H||Intrusion X||Zone1|
|Subsuite G||Dyke-swarm J||Subswarm P||Dyke O|
|Sill-complex K||Sill R|
|Suite E||Central complex L||Plug W|
Lithodemes need not be subdivided nor grouped together. In this hierarchical scheme each unit may have parent and child relationships with other units of greater and lesser rank respectively. Thus Pluton H has Subsuite F as its parent and is itself the parent of Intrusions X and Z.