Minor Intrusions

Minor Intrusions

 

small independent masses of igneous rock in the form of dikes, stocks, and irregular bodies confined to areas of disruptive tectonic displacement. Minor intrusions are differentiates of deep-seated chambers of basic magma and usually form at the end of periods of intensive magmatic activity. They are composed of porphyritic hybrid rocks that are from basic to acid and alkaline in composition. In many areas minor intrusions are closely associated with deposits of gold, tin, lead, zinc, and copper.

References in periodicals archive ?
As to columnist Paul Greenberg's attempt to justify Bush's illegal spying activities, I think Greenberg has trivialized a serious issue by stating that the whole spying operation is worth the minor intrusions on our privacy rights.
The subject has not been so thoroughly examined since 1970, they say, and could be of interest to igneous petrologists, volcanologists, structural geologists, and petroleum geologists and engineers working in sedimentary basins where minor intrusions contribute to basin architecture or act as hydrocarbon reservoirs or seals.
1988) (The Lovell court quoted the following from the Viera decision: "[s]ome investigative procedures designed to obtain incriminating evidence from the person are such minor intrusions upon privacy and integrity that they are not generally considered searches or seizures subject to the safeguards of the fourth amendment.