Hotspot tracks and the early rifting of the Atlantic

• Published in: Tectonophysics
• Main Author: Morgan, Jason W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 1983
• Subjects: Greenland; St. Helena
• Online Access: https://oceanrep.geomar.de/id/eprint/46858/; https://oceanrep.geomar.de/id/eprint/46858/1/morgan.pdf; https://doi.org/10.1016/0040-1951(83)90013-6

Many hotspot tracks appear to become the locus of later rifting, as though the heat of the hotspot weakens the lithosphere and tens of millions of years later the continents are split along these weakened lines. Examples are the west coast of Greenland-east coast of Labrador (Madeira hotspot), the south coast of Mexico-north coast of Honduras (Guyana hotspot), and the south coast of West Africa-north coast of Brazil (St. Helena hotspot). A modern day analog of a possible future rift is the Snake River Plain, where the North American continent is being “pre-weakened” by the Yellowstone hotspot track. This conclusion is based on reconstructions of the motions of the continents over hotspots for the past 200 million years. The relative motions of the plates are determined from magnetic anomaly isochrons in the oceans and the motion of one plate is chosen ad hoc to best fit the motions of the plates over the hotspots. However, once the motion of this one plate is chosen, the motions of all the other plates are prescribed by the relative motion constraints. In addition to the correlation between the predicted tracks and sites of later continental breakup, exposed continental shields correlate with the tracks. Their exposure may be the result of hotspot induced uplift which has led to erosion of their former platform sediment cover.