A large igneous province (LIP) is a large area of the Earth’s surface covered in magmatic (i.e., igneous) rock, typically basalt but also rhyolite, that erupted in a geologically short time, typically a million years. A large igneous province can be hundreds of meters thick, with a surface area of millions of square kilometers and a volume of a million cubic kilometers. Most large igneous provinces are formed by a volcano complex that releases about a cubic kilometer of lava per year (a lot) for at least a million years, though super-eruptions can release more than 2,500 cubic kilometers of magma in a single eruption.
The formation of new land around pre-existing cratons is the responsibility of large igneous provinces (continental cores). Central America, which was formed by volcanic activity, and the Caribbean islands are two examples. The entire area surrounding Indonesia is volcanically active, and the majority of the country’s islands are cooled magma rather than traditional cratons. All of the continents were formed by volcanic activity in the beginning, but the majority of them are so old that evidence of specific large igneous provinces in pre-Cambrian times is difficult to come by. Dike swarms, which deposit rock veins that cut abruptly across other rock strata and stand out to geologists, may have formed in ancient large igneous provinces.
Large igneous provinces may also be to blame for the majority of past mass extinctions. Large igneous provinces, unlike large asteroid impacts, are laid down with some regularity, and their duration of a million years places a constant strain on animal species. When large igneous provinces are laid down on land, these events are referred to as “flood basalts” or “flood basalt events.” The flood basalt event that created the Deccan Traps in India is thought to have played a role in the end-Permian mass extinction, also known as the “Great Dying,” which wiped out 95 percent of all land and sea species on the planet.
Ethiopia, the northwest United States, Brazil, Uruguay, South Africa, Antarctica, Russia, and China all have large igneous provinces today. Some massive igneous provinces span parts of continents that are now separated but were once connected. A large igneous province that spans parts of South Africa and Antarctica is one example. Both used to be part of the Gondwana continent.