Paleomagnetism of early Aphebian diabase dykes from the slave structural province, Canada

Early Aphebian dykes (lowermost Proterozoic) intrude the Archean terrain of the Slave Structural Province of the Canadian Shield and paleomagnetic results from them are reported. The Dogrib dykes, with an Rb/Sr age of 2692 ± 80 mm.y., have directions of magnetization directed toward the NW without reversals (16 sites; 309, + 37; α₉₅ = 4°; pole 35S, 050W). The Indin dykes, with an Rb/Sr age of 2093 ± 86 mm.y., have magnetization directed toward the SE with reversals (13 sites; 131, + 58; α₉₅ = 8°; pole 19N, 076W). Other, less well-documented data from a third dyke swarm (the “X” dykes) and a basic sill (the Duck Lake Sill), are also presented, and a very tentative polar path for the Slave Province in the earlier Proterozoic is given. This path is not greatly different from a similar very tentative early Aphebian polar path from the Archean Superior Province, considering the uncertainties in the paleomagnetic and age determinations. We interpret this to mean either that the intervening Hudsonian Structural Province (−1850 m.y.) was not the site of a wide plate-style opening and closing ocean, or if it was, the two bounding Archean cratons returned approximately to their original relative position.