Laser Ablation ICP-MS U-Pb and 40Ar-39Ar age constraints on Neoarchean to Paleoproterozoic magmatic and tectono-metamorphic evolution of the link between Hope Bay and Elu greenstone belts, northeast Slave craton, NWT, Canada

Abstract

The Elu Link connecting the Neoarchean Hope Bay and Elu granite-greenstone belts in the Bathurst block of the northeast Slave craton consists of volcano-sedimentary and gabbro–granite rocks. Laser ablation ICP-MS zircon and titanite U-Pb dating was combined with mineral 40Ar-39Ar age data to date the Elu Link rocks and D1–D3 tectono-metamorphic events, as well as characterize the response to the Thelon Orogeny in the area. The volcanic rocks are correlated with the ca. 2716Ma Flake Lake suite in the adjacent Hope Bay belt, whereas the sedimentary units have a minimum depositional age of 2684±11Ma nearly coinciding with the onset of D1 deformation. Most gabbro–granite bodies were emplaced between 2651±14Ma and 2577±13Ma coeval with the D2 deformation whose accompanying metamorphism culminated at 2632±7Ma. Older ages (up to 3042±22Ma) retained by either the gabbro–granite or their hosts are indicative of crustal contamination. A few gabbro–granites were also emplaced during the 2577±13Ma to 2494±21Ma D3 deformation event. However, the 2494±21Ma intrusions are unusual and mark the Archean–Paleoproterozoic transition. The D3 deformation was followed by erosional exhumation and localized thermal pulses associated with the emplacement of diabase dikes at 2228±8Ma, 2128±11Ma, and 802±75Ma. The Thelon Orogeny imprint, inferred from the 2054±11Ma to 1919±5Ma biotite ages, corresponds to nearly isobaric, low-temperature (<350°C) metamorphic re-equilibration.