GEOTECTONICS OF THE HANSON LAKE BLOCK, TRANS-HUDSON OROGEN, CENTRAL CANADA - A PRELIMINARY PALEOMAGNETIC REPORT

We present paleomagnetic results from the Sahli granite in the Hanson Lake block of the Trans-Hudson orogen. Evidence shows that the Sahli g ranite magnetization was acquired during a metamorphic event which pro bably peaked in the interval 1840-1800 Ma. The reset nature of the Sah li granite data is partly supported by a negative contact test from a cross-cutting mafic dyke. The Sahli granite results and those from the 1834+/-2 Ma Hanson Lake pluton and Jan Lake granite in the Hanson Lak e block indicate high paleolatitudes compared with the low paleolatitu des found for the Wathaman batholith and other rocks of the Slave-Rae- Hearne cratons of similar ages to the north-west of the Trans-Hudson o rogen. Estimates of the 'north-south' width of about 4000 km for the P aleoproterozoic Manikewan ocean between the Archean Hearne and Superio r cratons using the Hanson Lake pluton and Wathaman batholith poles, f or example, are consistent with previous estimates. The angular differ ence between the Hanson Lake pluton and Sahli granite poles provides a n apparent polar wander segment of the geomagnetic field for the Hanso n Lake block to compare with the parallel segment given by the poles f or the 1851 Ma Reynard Lake pluton and the 1838 Ma Boot Lake-Phantom L ake pluton for the adjacent Flin Flon domain. Both segments indicate a relative north-northeasterly path direction at an apparent polar wand er rate within the range 4.3-0.4 degrees per Ma, assuming no large-sca le regional tilts of the plutons. The offset between the two apparent polar wander path segments indicates either an 'east-west' component o f closure of about 1000 km for the Manikewan ocean or vertical-axis co unter-clockwise rotation of units within the Trans-Hudson orogen with respect to the Superior craton plus a possible north-south relative tr anslation between the Hanson Lake block and Flin Flon domain. (C) 1998 Elsevier Science B.V.