Laccolith


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laccolith

[′lak·ə‚lith]
(geology)
A body of igneous rock intruding into sedimentary rocks so that the overlying strata have been notably lifted by the force of intrusion.

Laccolith

 

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.
Mineralization is zoned concentrically about the San Pedro Peak laccolith. The mineralized zone is high in copper near the intrusion and becomes more lead-zinc rich with increasing distance from the peak (Megaw, 1991).
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. The zones are incorporated into three separate open pits (El Valle, Boinas East and Boinas West - now exhausted) and the Black Skarn underground development.
Coal formations, located in two synclines (Gorce and Sobiccin) separated by the Chetmiec rhyolite laccolith, are often disturbed by tectonic discontinuities and porphyry intrusions.
(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., 2007).
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--3.5 km (Rocchi 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.
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.
The prospect intrusion is a small, differentiated dolerite laccolith containing shrinkage cavities and miarolitic cavities lined with a variety of interesting minerals including prehnite, pectolite, analcime, albite and pyroxene.
At Fort Lewis, the habitat is montane shrubland (11) superimposed on intrusive igneous rocks forming laccoliths (12).
The general ecosystem of the area is montane shrubland (2) superimposed on intrusive igneous rocks forming laccoliths (3).