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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 ?
Hence, sheet-like magmatic intrusion of laccoliths appears as a possible and plausible mode of formation for the dome Ha2.
The recent numerical modelling and scaling analysis by Michaut (10,11) of the magmatic intrusion processes leading to the formation of laccoliths strengthens the hypothesis of an intrusive origin of large and low lunar domes similar to those described in this study and our preceding works.
Dynamics of magmatic intrusions in the upper crust; Theory applications to laccoliths on Earth and the Moon', J.
Kerr & Pollard23 introduce a laccolith model in which they treat the overburden of the pressurised magma as an elastic plate.
When assuming an intrusive origin of the dome Ha2, this would indicate that laccolith formation proceeded until the second stage, characterised by flexure of the overburden.
Thomson and Schofield report on the relationship between sills, dykes, laccoliths and pre-existing basin structure in the NW European Atlantic Margin through the use of high-resolution 3-D seismic images.
also on Elba, focused their work on a late Miocene complex of nested Christmas-tree laccoliths, plutons and dykes.
Two-stage growth of laccoliths at Elba Island (Italy).
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 much more voluminous intrusion formed the Christmas-tree laccolith made up of four major layers which are interconnected and accompanied by minor dykes and sills.
Higher in the section, exposed in central Elba, the main intrusion formed a Christmas-tree laccolith with four parallel, gently westward-dipping layers (cumulative thickness of about 1000 m) connected by dykes.
Contacts with surrounding country rock, including the laccolith units of the dome, are mostly intrusive in nature and dip away from the pluton.