Tertiary Basalts of Baffin Bay: Geochemical Evidence for a Fossil Hot-Spot

Abstract

Tertiary basalts found on land in Baffin Island and western Greenland, and offshore western Greenland have been divided into several types produced at comparable evolutionary stages within the different areas. Their occurrence, seismic evidence and bathymetric evidence suggests that the general region of Davis Strait, the sill between Baffin Bay and Labrador Sea, was a hot-spot in the early Tertiary. Chemical variations within basalts at comparable evolutionary stages change geographically in the same manner as do changes in basalt chemistry from the Reykjanes Ridge to Iceland, a modern hot spot. If the analogy is correct the sense of direction of the changes suggests that the centre of the hot spot in the early Tertiary lay in the northern part of the offshore province, some distance from the present bathymetric sill of Davis Strait. The analogy may not, of course, be correct — the changes in chemistry observed may reflect other factors (such as height within the basalt pile), and the spatial variations may be simply an accidental by-product of these factors. If it is real, it suggests that geochemical search for former hot-spots, now dormant, may be profitable.