When the Earth has indigestion, it belches massive amounts of basaltic material from its interior producing a Large Igneous Province (LIP) over a geologically short period of time. The volume of basalt produced at an LIP often exceeds the volume of basalt produced at a mid-ocean ridge system. LIPs are associated with continental breakup and regional-scale continental uplift. The oldest LIP has been dated to 2.5 billion years ago, but the most well preserved features have erupted since the breakup of the Pangean supercontinent, approximately 250 million years ago.
Besides scientific curiosity, scientists are interested in LIP formation because the massive eruption of igneous material affects the planet by radically altering climate conditions and producing mass extinctions of life on land and in the ocean.
Conventional wisdom holds that the basaltic material is produced by a persistent magma plume rooted deep in the mantle, similar to hot spots. But not all scientists agree. Scientists at the California Institute of Technology calculated the temperature of normal mantle temperature and found that most LIPs formed from magma that erupted within this temperature range. The thermal model would require a hotter than normal mantle plume to produce an LIP, but a change in mineralogy could explain these features.
The mineral eclogite is a coarse grained metamorphic rock that has a low melting point. This means that eclogite melts easier in the mantle than peridotite, the most common mantle rock. Many scientists believe that mantle rock is constantly being affixed to the underside of continental lithosphere causing it to grow through a process called underplating. When the igneous rock extends to a depth greater 150 ft (50 m), the rock experiences a change in pressure and is metamorphosed forming eclogite. When the eclogite is sheared off of the base of the lithosphere, it sinks into the mantle and melts.
The eclogite acts like a fertilizer changing the chemistry of the surrounding mantle. As the melted eclogite mixes, it warms the surrounding mantle through conduction, the process by which heat is transferred from molecule to molecule. This process could explain the massive volume of basaltic material that could rise and melt efficiently through the underside of the lithosphere. Over time, the overlying lithosphere is thinned to the point that it ruptures and the magma pulses out producing a massive outpouring of igneous material.
The pulse of melting magmatic material could bow the continental crust upward producing uplift that can be as high as 1 mile (2 km). Continental uplift can also be accentuated by the act of shearing off a slice of underplated material, which leaves a void on the underside of the lithosphere. As the island of eclogite sinks into the peridotite-rich mantle, the surrounding mantle fills in the void on the underside of the lithosphere and begins to melt and thin the lithosphere, causing it to bow upward enhancing continental uplift. Over time, the process of underplating repairs the underside of the lithosphere.
EarthSpin 
fascinating…I have silly ‘uneducated in these matters’ question…
so where does this ‘belching’ occur? is it underground? in volcanoes? at fault lines? you mention the mid-ocean ridge system…does this phenomenon only occur under water?
That is a great question! A large igneous province is a massive eruption of basaltic material (like the rocks that line the Columbia River Gorge) at the Earth’s surface. On land an LIP is called a flood basalt. In fact, the Columbia River Gorge IS a flood basalt. So you have an LIP in your own back yard in Oregon. When an LIP is erupted in the ocean, it forms an ocean plateau. LIPs are believed to follow major events, like continental break up. – Great Question!