12 - Regional Distribution of Ferrar Magmatic Centers

Summary

Ferrar-style dolerites are found throughout the Transantarctic Mountains, running some 4,000 km across Antarctica; extending to Tasmania and South Africa to the Karoo system. An unusual characteristic of the Ferrar system is the extreme paucity of dike swarms that might well be expected in rifting systems. Major dike swarms are found in Canada and somewhat in the Eastern North American Rift System, but not so in Antarctica. The concentrated center of magmatic activity exhibited in the Dry Valleys is similar to what is found along ocean ridges, which is characterized by a series of spatially distributed major magmatic centers with underlying magmatic mush columns. Magma is produced and moves upward through the mush column and is distributed laterally, up and down the ridge by high level flow. The Ferrar may also be like this, as indeed most magmatic systems are, and then, where are the other such centers along the Transantarctic Mountains? The Dufek complex is clearly once such center and others may exist at various places along this range; there is telltale evidence at many locations. And it is remarkable that, by and large, there are always four major sills at most locations.