DETRITAL ZIRCON U-PB AND FISSION-TRACK DOUBLE-DATING OF LOWER CRETACEOUS HIBERNIA FORMATION STRATA IN THE JEANNE D'ARC BASIN, OFFSHORE NEWFOUNDLAND

The precise timing, rates, and spatial patterns of tectonic exhumation along modern magma-poor rift margins are uncertain globally. The Newfoundland-Iberia rift system evolved during the Triassic to Cretaceous opening of the North Atlantic Ocean and provides an ideal opportunity to study the long-term development of magma-poor rift margins. During rift evolution, changes from coupled to decoupled extension result in several architectural domains that record progressive phases of thinning, mantle exhumation, and lithospheric breakup. In this study, Lower Cretaceous strata of the Hibernia Formation were analyzed using detrital zircon U-Pb and fission-track double-dating to investigate how phases of rift evolution affected the filling of syn-rift, proximal domain basins along the Newfoundland margin. Reservoir sandstones were sampled in the Hebron and Hibernia oil fields and nearby regions of the central Jeanne d’Arc basin. New results show Hibernia Formation samples contain mostly Archean to Paleozoic (~99%) detrital zircon grains with minor Mesozoic input. Late Neoproterozoic to Mesozoic fission-track ages are observed within all U-Pb age populations. Double-dated grains indicate that cooling was mostly due to tectonic exhumation processes, however, there are Late Neoproterozoic to Cretaceous magmatic-cooled grains. We interpret that the Archean to Paleozoic grains were recycled through mature, upper Paleozoic strata of the Avalon uplift to the south of the Jeanne d’Arc basin. Mesozoic magmatic-cooled zircon grains indicate minor syn-depositional volcanic input from Cretaceous volcanic systems in the southern Grand Banks. Late Neoproterozoic to Mesozoic fission-track ages presumably record exhumation associated with Appalachian evolution and Mesozoic rifting. Mesozoic fission-track ages reveal periods of exhumation during the Late Triassic-Early Jurassic and Early Cretaceous that coincide with phases of thinning and mantle exhumation along the Newfoundland margin, respectively. The Hibernia Formation results demonstrate the usefulness of zircon double-dating to evaluate timing and patterns of tectonic exhumation in proximal domain basins. Ongoing research will further investigate connections between Jeanne d’Arc basin strata and development of the Newfoundland margin.