Also found in: Dictionary, Wikipedia.


A body of igneous rock intruding into sedimentary rocks so that the overlying strata have been notably lifted by the force of intrusion.



mushroom-shaped (bun-shaped) mass of igneous rock formed when magma intrudes between layers of sedimentary rock; the layers of sedimentary rock are moved apart and raised in a domelike shape above the intrusion.

References in periodicals archive ?
Kerr & Pollard23 introduce a laccolith model in which they treat the overburden of the pressurised magma as an elastic plate.
The long dikes were required to account for the rille's two arms, and the laccolith was necessary to provide a void for the collapse that formed Hyginus.
Mineralization is zoned concentrically about the San Pedro Peak laccolith.
2000, Tertiary phonolite laccolith of Marianska hora Hill, N Bohemia: Geological, petrological and mineralogical characteristics, Acta Montana, ser.
Located near the southern end of the Rio Narcea gold belt 16 km south of the town of Salas, El Valle consists of five major zones of gold mineralisation within an 800 m radius that form a single, northeast-oriented mineralised system around the Boinas laccolith.
2003), in the Median Subbetic (Betic Cordillera), recorded and analysed saponite at the contact of marl-limestone rhythmites with a laccolith of dolerites as a consequence of hydrothermal alteration facilitated by an intense fracturation and the circulation of lower-temperature fluids; in the slightly altered rocks Ca-zeolites were also found (Jimenez-Millan et al.
The bedrock of the profile U-II is a marginal analcime-phyric facies of the phonolite laccolith that grades into amygdaloidal natrolite-sodalite phonolite in the laccolith centre.
The magmatic sequence led to the formation of a nested Christmas-tree laccolith complex with a total thickness of about 2400 m of porphyritic rocks emplaced at depths of 2--3.
This dome is not a laccolith, but rather a large breccia "hill" overlain by an 11,000 to 15,000-foot-thick sequence of sedimentary rocks.