Detrital zircon data suggest multiple Cryogenian–Cambrian active margins along northern and western Baltica and close ties with Siberia

Abstract

Deciphering the history of active continental margins is of key importance for paleogeographic reconstructions, but the low preservation potential of such margins commonly hampers such attempts and may introduce unrecognized biases. Here, we present new sedimentological observations and detrital zircon U–Pb and Hf isotopic data from the Ediacaran–Cambrian Vestertana Group in Finnmark, Arctic Norway. The data are consistent with derivation from the Fennoscandian Shield and the appearance of an Ediacaran source at the Ediacaran–Cambrian transition. However, the new paleocurrent observations dispute that this influx is related to a change in paleocurrent direction from northerly to southerly. Instead, we argue for the possibility of an alternative source represented by the Kalak Nappe Complex, which we suggest may be a remnant of a Neoproterozoic accretionary margin outboard of western Baltica that was thrust onto Baltica during the Ediacaran rather than during the Silurian Caledonian Orogeny. Further work focusing on detrital minerals other than zircon may provide a more comprehensive understanding of the character of these potential sources. Comparisons with detrital zircon data from Ediacaran–Cambrian sedimentary rocks around the North Atlantic show that both Baltica and Siberia are characterized by large Neoproterozoic populations, while such ages are all but absent from Laurentia. The apparent link between Baltica and Siberia during the Ediacaran–Cambrian is consistent with fossil data and suggests that the two continents were separated from Laurentia by this time.