Paleomagnetism of ca. 2.13–2.11 Ga Indin and ca. 1.885 Ga Ghost dyke swarms of the Slave craton: Implications for the Slave craton APW path and relative drift of Slave, Superior and Siberian cratons in the Paleoproterozoic

Abstract

Of ∼35 Archean cratons that have been identified around the globe, only one, the Superior craton of the Canadian Shield, has a reasonably well-defined apparent polar wander (APW) path for much of Paleoproterozoic time based on ‘key’ (i.e., well-defined and precisely dated) paleopoles. As a result it has been difficult to compare the drift of these cratons or reliably test continental reconstructions of the Archean cratons in the Paleoproterozoic based on paleomagnetism. In this study, we report key paleopoles for the 2.13–2.11 Ga northwest- to north-northwest-trending Indin dyke swarm (36° N, 76° W, A95=7°) and the 1.885 Ga northeast- to north-northeast-trending Ghost swarm (2° N, 106° W, A95=6°) of the Yellowknife region of the Slave craton. U-Pb baddeleyite ages have been determined at paleomagnetic sampling sites and baked contact tests establish that the remanences are primary. Combined with paleopoles from other precisely dated dyke swarms of the Slave craton, these data define a rudimentary APW path between ca. 2.23 and 1.885 Ga, and permit a comparison of the drift of the Slave and Superior cratons over this interval. Both the Indin and Ghost poles are precisely matched in age with key poles on the Superior APW path. The Slave and Superior paths are not superimposed demonstrating that the two cratons were not in their present relative locations. They have different overall shapes indicating relative drift during at least a portion of the period. However, the earlier (2.23–2.21 Ga) portions of the tracks appear broadly similar and could permit the two cratons to be on a single tectonic plate at that time, although separated by a great distance. A comparison of the Ghost pole and a coeval key pole for Siberia permits a 1.88 Ga reconstruction with southern Siberia facing the northern Slave/Laurentia margin, broadly similar to reconstructions that have been proposed at least as late as 1.38 Ga, although the distance between the cratons is still poorly constrained.