EVIDENCE FOR AN EARLY PROTEROZOIC CRUSTAL PROVINCE IN THE NORTH-ATLANTIC REGION

Published Sm-Nd data for the Ketilidian belt of Greenland, the Rockall bank in the North Atlantic, and the Islay-Inishtrahull block of the British Isles are used to suggest the existence of a single Early Proterozoic crustal province in the North Atlantic region with a crustal formation age of c. 1.96 Ga. The three sub-provinces also have similar metamorphic histories, as documented by Sr and Pb isotope data. They probably represent one or more island arcs which were accreted to the Laurentian craton 100 Ma later, in the 1.85 to 1.75 Ga Ketilidian-Laxfordian orogeny. A line of suture between the Archaean craton and Early Proterozoic accreted terranes is tentatively proposed.