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Identified mantle components are DMM (depleted mid-ocean ridge basalt (MORB) mantle), HIMU (high U/Pb-ratio mantle), EM1 (enriched mantle 1), EM2 (enriched mantle 2) and FOZO (focus zone). [ 22 ] [ 23 ] This geochemical signature arises from the mixing of near-surface materials such as subducted slabs and continental sediments, in the mantle ...
It was later postulated that hotspots are fed by streams of hot mantle rising from the Earth's core–mantle boundary in a structure called a mantle plume. [6] Whether or not such mantle plumes exist has been the subject of a major controversy in Earth science, [4] [7] but seismic images consistent with evolving theory now exist. [8]
There are various sources identified for ocean island basalt magma in Earth's mantle but the main component is ancient recycled basaltic oceanic crust which has inherited the trace element and isotopic signatures of a subduction zone dehydration process, with enrichment in high field strength elements. [5]
A flood basalt (or plateau basalt [1]) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the Earth via a mantle plume. [2]
Mantle plumes were first proposed by J. Tuzo Wilson in 1963 [4] [non-primary source needed] and further developed by W. Jason Morgan in 1971. A mantle plume is posited to exist where hot rock nucleates [clarification needed] at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. [5]
CLIP formed as a large igneous province and now forms a thickened zone of oceanic crust between the North American and South American plates. [2] In some places the oceanic crust is 2–3 times as thick as normal oceanic crust (15–20 km (9.3–12.4 mi) vs 7 km (4.3 mi).
The Saint Peter and Saint Paul Archipelago and complex lies in the equatorial Atlantic Ocean. It is 90 km long and 4000 m tall. The apex forms the Saint Peter and Paul Rocks. This is one of the few known examples where sea floor mantle rocks are exposed above sea level.
The weak visibility of the postulated plume in tomographic images of the lower mantle and the geochemical evidence for eclogite in the mantle source have led to the theory that Iceland is not underlain by a mantle plume at all, but that the volcanism there results from processes related to plate tectonics and is restricted to the upper mantle ...