Large Igneous Province

A large igneous province (LIP) is an extremely large accumulation of igneous rocks—intrusive, extrusive, or both—in the earth's crust. In 1992 researchers first used the term large igneous province to describe very large accumulations—areas greater than 100,000 square kilometers (slightly larger than the area of Portugal)—of mafic igneous rocks that were erupted or emplaced at depth within an extremely short geological time interval: a few million years or less. Mafic, basalt sea floors and other geological products of 'normal' plate tectonics were not included in the definition.

The definition of LIP has been expanded and refined, and is still a work in progress. LIP is now frequently also used to describe voluminous areas of, not just mafic, but all types of igneous rocks. Sub-categorization of LIPs into large volcanic provinces (LVP) and large plutonic provinces (LPP), and including rocks produced by normal plate tectonic processes, has been proposed.

The source of many or all LIPs is variously attributed to mantle plumes or to processes associated with plate tectonics.

Some LIPs are now intact, such the basaltic Deccan Traps in India, while others have been dismembered by plate tectonic motion, like the basaltic Central Atlantic Magmatic Province (CAMP)—parts of which are found in Brazil, eastern North America, and north-western Africa.