Chapter 24 - Large Igneous Provinces and Flood Basalt Volcanism

Abstract

Large igneous provinces (LIPs) represent huge volumes of erupted and intruded magma and are exceptional volcanic events in Earth history. They were erupted over a brief period of geologic time. The volume of magma emitted during each individual eruption that makes up an LIP (frequently 103 to perhaps 104 km3) is also exceptional, and these form Earth's largest eruptions. LIPs occur on continental crust (flood basalt provinces) and in ocean basins (oceanic plateaus), and at the transition between continents and oceans (“volcanic-”divergent margins). Basaltic LIPs usually form within a geologically brief period of time, especially the climax, or peak, of volcanic output, which may be less than 1 million years in duration. The eruptions that form flood basalt provinces have been proposed as a cause of major environmental perturbations throughout much of Earth history, including mass extinctions. Pāhoehoe-type lavas dominate in flood basalt provinces, and eruptions are thought to have durations of decades to perhaps centuries. The huge flow fields of pāhoehoe lavas are dominated by sheet lobes in many provinces, as well as alternations with flow fields dominated by smaller inflated lava lobes. Vents are poorly known, but some, at least, were long fissure-type systems.