continental flood basalts

continental flood basalts Continental flood basalts (CFBs) are the largest volumes of basalts that are found on the continents, having volumes of thousands of cubic kilometres; some flows, such as those of the Deccan in India and the Columbia River in the north-western United States, extend for hundreds of kilometres. The Snake River Plain in the north-western USA is the only area in which flood basalts are currently erupting, but it is thought that volcanic emissions from larger earlier eruptions might have been sufficient to change global climate, perhaps even causing a ‘nuclear winter’.

CFBs are generally of tholeiitic composition, but show signs of contamination by crustal material.

Modern theories ascribe the formation of CFBs to melting of the Earth's mantle as a direct consequence of a continent being pulled apart over a plume of hot material rising from deep in the mantle. This hypothesis is supported by the existence of CFB provinces in Brazil and South Africa, which can be closed matched. The eruptions that produced these basalts took place before the opening of the South Atlantic in Cretaceous times.

Judith M. Bunbury