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Variation in the Thermal Gradient, Degree and Melt Segregation Pressure and Axial Depth Along the South Atlantic Ridge
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 2nd International Congress of the Brazilian Geophysical Society, Oct 1991, cp-316-00117
Abstract
Several lines of evidence suggest a cooler upper mantle southward beneath the South Atlantic Ridge. Among them is the distribution of hotspots in relation to the ridge, the decrease of eruption temperature southward, and behavior of trace elements wich are incompatible in basaltic melt. Further evidence includes the deepening of the ridge axis, and general decrease in geoid anomaly (Kane and Hayes, 1989) which could be a consequence of a higher subsidence rate in this direction due to a cooler mantle. The modeling of upper mantle cooling toward the south could be a consequence of influence of hotspots. It is assumed here, based on the fact that a linear relation between hotspots and their distance from the ridge axis only exists for those hotspots located at less than 800knl from the ridge.