lopolith

lopolith

[lop-uh-lith]
noun Geology.
a mass of igneous rock similar to a laccolith but concave downward rather than upward.

Origin:
1915–20; < Greek lop(ós) shell, husk + -o- -o- + -lith

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World English Dictionary
lopolith (ˈlɒpəlɪθ)
 
n
Compare laccolith a saucer- or lens-shaped body of intrusive igneous rock, formed by the penetration of magma between the beds or layers of existing rock and subsequent subsidence beneath the intrusion
 
[C20: from Greek lopas dish + -lith]

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American Heritage
Science Dictionary
lopolith   (lŏp'ə-lĭth)  Pronunciation Key 
A large, bowl-shaped body of igneous rock intruded between layers of sedimentary rock. Lopoliths are usually connected to a dike and are typically tens of kilometers thick and hundreds of kilometers wide.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

lopolith

igneous intrusion associated with a structural basin, with contacts that are parallel to the bedding of the enclosing rocks. In an ideal example, the enclosing sediments above and below the lopolith dip inward from all sides toward the centre, so that the lopolith is concave upward. Lopoliths, which can be several miles to several hundred miles in diameter, with thicknesses up to several thousand feet, are some of the largest igneous intrusions known. Many large ones are composed dominantly of basic rocks; a classic example is the Bushveld Igneous Complex of South Africa, which is composed of both granite and basic rocks. Many other lopoliths are either composite or differentiated. The feeder of a lopolith is assumed to be relatively small and probably is centrally located; it may connect the lopolith with a larger magma chamber at greater depth.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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