-
f Petrology and Geochemistry of the South Atlantic Ridge from 0° to 42° S
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 5th International Congress of the Brazilian Geophysical Society, Nov 1997, cp-299-00294
Abstract
Petrological and geochemical variations along the South Atlantic Ridge show that eruption temperatures for the South Atlantic Ridge primitive basaltic glasses (MG#>64) decrease systematically along the ridge to the south from 0° to 42°S which appears to be related to the lower mantle temperature gradient. The lower mantle (below the 650 km discontinuity) beneath the South Atlantic shows a lower seismic P wave velocity with a gradual increase southward (around 42°S) (Dziewonski, 1984). This seismic velocity is related to temperature, or degree of melt, where higher seismic P wave velocities indicate colder material. The lower mantle temperature also seems to play an important role in controlling the degree and volume of melting along the South Atlantic Ridge.