Large Igneous Provinces and Plate Tectonics

© 2000 by the American Geophysical Union. Large Igenous Provinces (LIPs) constitute broad areas, > 10 5 km 2 , of mafic volcanic and plutonic rocks erupted over ~106 yr. Compared with plate dimensions, LIPs are smaller, localized features; they form both in plate interiors and at plate boundaries. LIPs originate in the mantle, via mass and energy transfer which acts both independently o￡ and in conjunction with, the wide-ranging upwellling systems producing new oceanic crust by sea floor spreading along the mid-oceanic ridge system. Plate tectonic theory does not readily explain the massive magmatism, which is most commonly attributed to mantle plumes. Most LIPs form in extensional oceanic or continental plate tectonic settings, suggesting a relationship with thinned lithosphere. Deformed LIP complexes in intraplate continental settings suggest formation throughout most of Earth history. The post-150 Ma LIP record reveals both many events and large melt volumes from 135-85 Ma, and a distinct decline since 50 Ma. These trends may reflect variations in mantle circulation and have links to global environmental change. Following formation, oceanic LIPs may be carried laterally by the plates to regions of plate convergence. Subsequent accretion of major LIPs into continental crust contributes episodically to continental growth.