Sedimentary provenance analysis by coupled detrital zircon U-Pb, Hf isotopes of the Paleoproterozoic Belcher Group, Nunavut, Canada and implications for sedimentation during the opening and closure of the Manikewan Ocean

Abstract

Coupled detrital zircon U-Pb, Hf isotopic data from the Paleoproterozoic Belcher Group, Nunavut, Canada, are presented to determine maximum depositional ages and sedimentary provenance. We use these data to evaluate potential sediment sources with matching ages and εHf values within a paleogeographic context, to better define the configuration of microcontinents, terranes, and cratons surrounding the Belcher basin during its deposition. The distribution of detrital zircon spectra show that the lower Belcher Group was deposited on the passive margin of the Superior craton, whereas the upper Belcher Group (Omarolluk and Loaf formations) was deposited in syn-orogenic phase, broadly reflecting the opening and closing stages of the Manikewan Ocean, respectively. The lower Belcher Group data show dominant detrital zircon populations between 2825 and 2690 Ma (associated with negative εHf values) with only minor detrital input from sources < 2100 Ma. The dominant grain population is interpreted to be derived from the northeastern Superior craton (>2680 Ma grains), and the Winnipeg River and North Caribou terranes (<2680 Ma grains). The upper Belcher Group shows a dramatic shift in detrital ages from Archean to dominantly Paleoproterozoic, with dominant age peaks between ca. 1920 and 1900 Ma and only minor Archean input that includes 2500 Ma sources that are absent in the lower units. Archean populations document Sask craton-like ages and εHf values, whereas the dominant detrital 1920 to 1900 Ma age population shows positive εHf values that are consistent with being sourced from terranes located in the western Reindeer zone deposited in a submarine fan.