Large mafic magmatic events through time and links to mantle plume heads

We identify 304 mafic magmatic events ranging in age from ca. 3500 Ma to the present and assess their potential for linkage to the arrival of mantle-plume heads. For each, we catalogue components (flood basalts or their erosional remnants, giant mafic dike swarms, mafic sill provinces, and mafic-ultramafic layered intrusions), age constraints, and references to published literature. On the basis of criteria involving large amounts of magma emplaced in a short time, and/or giant radiating dike swarms, 34 events have been confidently linked to the arrival of a mantle-plume head. By using other criteria including geochemistry, an additional 194 events are considered probably related to plume arrival. The remaining 76 events, the majority of which are rift related, require further study to assess the plume-head link. Our analysis of the events that are confidently or probably linked to plume arrival yields several preliminary conclusions. Plume-head events occur throughout the geologic record since at least 3500 Ma and probably since 3800 Ma, with no plume-free intervals greater than similar to200 m.y. Plume arrival does not follow any obvious periodicity. Plume-head locations are known for only a handful of events. However, in such cases, associated sills and flow packages can be emplaced (presumably via lateral flow in dikes) as far as 2500 km away from the plume center. There are numerous precise age correlations between mafic units on different continents. However, further work is required to determine which coeval events can be reconstructed into a single plume event and which represent separate events occurring at the same time.