Distribution of the global Phanerozoic LIPs. Most LIPs are marked in red showing that they were constructed between 150 Ma and 50 Ma, which obviously represents a very active time for the mantle.

Large Igneous Provinces (LIPs) are massive magma emplacements and intrusions. While their formation process is still under heavy discussion, their environmental impact and relevance is not debated. Understanding the chronological, petrological, and geodynamic development of LIPs is hence very important.

LIPs can be found both on continents and in the ocean and include continental flood basalt provinces (CFBP), volcanic passive margins, oceanic plateaus, submarine ridges, and ocean-basin flood basalts. The magmatism associated with LIP formation is currently estimated to represent about 10 % of the mass and energy transfer from the Earth’s deep interior to the surface. This transfer is distinctly episodic in geological time periods, i.e. in millions of years. LIPs are found to have had a significant effect on the environment. Subaerial basaltic eruption release enormous amounts of heat and of volatiles such as CO2, S, Cl, and F. Depending on latitude, those volatiles can easily reach the stratosphere (12-50 km of the atmosphere), where they have a longer residence time and greater global dispersal and therefore greater impact on climate. The emplacement of LIPs have further been identified to have caused a massive release of methane via melting of gas hydrates.

It is assumed that oceanic plateaus and CFBP are constructed by eruptions from a vent system or a set of fissures. This way different magma-supplying locations acting almost simultaneously can form a single LIP as we can observe e.g. for Iceland, which is a conglomerate of a number of volcanoes.

Looking up the ages of the globally observed LIPs it is interesting to note that most were formed during the period 150-50 million years. Much fewer LIPs were emplaced before 150 million years or after 50 million years. Seafloor spreading rates are also found to be high during a large part of this period. The episodicity in LIP emplacement appears to reflect variations in rates of mantle circulation with the period 150-50 million years representing a very active time, a kind of ‘mantle heartburn’. At the same time (~145 million years to ~50 million years) the global oceans were characterised by strong chemical variations, high temperatures, high relative sealevel, episodic deposition of black shales, high production of hydrocarbons, and mass extinction of marine organisms. A causal relationship of these environmental changes with the emplacement of LIPs is suspected. 

To quantify and really grasp the environmental impact the construction of a specific LIPs has had, detailed seismic studies in combination with sampling of not only the surface but the deeper structure (by drilling) are needed. This then should be supplemented by the numerical simulation of the spreading of volatiles and heat in both atmosphere and the ocean and a modelling of the effect on flora and fauna.