North Atlantic magmatism controlled by temperature, mantle composition and buoyancy

• Published in: Nature geoscience Vol. 7; no. 11; pp. 820 - 824
• Main Authors: Brown, Eric L., Lesher, Charles E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-11-2014; Nature Publishing Group
• Subjects: 704/2151/209; 704/2151/210; 704/2151/213; Earth Sciences; Earth System Sciences; Geochemistry; Geology; Geophysics/Geodesy; Heterogeneity; High temperature; Lava; letter; Magma; Mathematical models; Melting; Oceanic crust; Upwelling
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/ngeo2264

Compositional variations in the mantle can generate anomalous magmatism, calling into question the need for hot, upwelling mantle plumes. Numerical simulations, however, point to a plume source for the North Atlantic large igneous province.
Large igneous provinces are characterized by anomalously high rates of magma production
1
. Such voluminous magmatism is commonly attributed to partial melting of hot, buoyantly upwelling mantle plume material
2
,
3
. However, compositional heterogeneity in the mantle, caused by the subduction of oceanic crust, can also enhance magma production, diminishing the need for elevated temperatures associated with upwelling plumes
4
,
5
. A plume origin for the North Atlantic large igneous province has been questioned because lava compositions correlate with crustal thickness, implying a link between magma productivity and mantle source composition
4
,
6
. Here we use a numerical model that simulates upwelling and melting of compositionally heterogeneous mantle material to constrain the conditions that gave rise to magmatism in the North Atlantic. Using observations of lava compositions and volumes from the North Atlantic, we show that subducted crustal material represented less than 10% of the mantle source. We further show that mantle temperatures have remained elevated by 85–210 °C and increased mantle upwelling up to 14 times the rate of plate separation has occurred over the past 56 Myr. The enhanced temperatures and upwelling rates extended along more than 1,000 km of the Palaeogene rift, but are substantially more restricted along the modern Mid-Atlantic Ridge. These findings reflect the long-term manifestation of a mantle plume.