Detrital zircon age constraints on basement history on the margins of the northern Rockall Basin

Detrital zircon dating has proven to be an effective way to constrain ages of submerged basement terranes on the margins of the northern Rockall Basin, a region where direct evidence of crustal affinities is scarce or absent. Zircons have been dated from sandstones of Paleocene–Oligocene age known to have been derived from the east (Hebridean Platform) and west (Rockall and George Bligh highs). The results show that the Hebridean Platform is a westward extension of the Lewisian Complex, with Archaean and Palaeoproterozoic ages that can be directly correlated with events identified in the Outer Hebrides and NW Scotland. The detrital zircons derived from the Hebridean Platform also provide evidence for a Mesoproterozoic thermal event and two phases of intrusions in the Palaeozoic. The Rockall High consists of a Palaeoproterozoic terrane dated as c. 1760–1800 Ma, similar to ages previously determined from both basement samples and detrital sediment. The data also provide evidence for the subsequent intrusion of alkaline igneous rocks in the Paleocene–Eocene. The George Bligh High represents an Archaean terrane heavily affected by Palaeoproterozoic tectonothermal events, and was also the site of intrusion of alkaline igneous rocks during Paleocene time.