Siliciclastic sequences accumulated along the eastern margin of Laurentia during the late Neoproterozoic to early Paleozoic as a result of the breakup of Rodinia and formation of the Iapetus Ocean. Detrital zircon data show considerable variability in provenance of time-equivalent units that has implications for paleodrainage and paleogeography. Samples from northwest Scotland and northeast Greenland show detrital zircon U-Pb age groupings dominated by Archean and Paleoproterozoic populations consistent with derivation largely from the West Greenland segment of the North Atlantic craton. In Scotland, time-equivalent outboard sedimentary sequences show contrasting Archean and Proterozoic populations, including a substantial ca. 1.1-1.0 Ga component, indicative of derivation from the Grenville orogen to the southwest. These contrasting paleodrainage patterns, consistent with paleocurrent data, must have developed during the early phase of passive-margin thermal subsidence and may have been accentuated by remnant rift shoulders. In Newfoundland and the U.S. Appalachians, time-equivalent sedimentary sequences are located within the hinterland of the Grenville orogen and are dominated by ca. 1.1-1.0 detritus with very few pre-Mesoproterozoic grains. The Grenville deformation front in these areas may have constituted a drainage divide that limited sediment input from the cratonic interior.
- Detrital zircon