THE SELWYN BASIN, YUKON: NOT A PANACEA FOR RECONCILING ENIGMATIC TERRANE DISPLACEMENTS

Internally consistent, shallow paleomagnetic inclinations from the Carmacks Group, Yukon imply large amounts of translation (~2000 km after 70 Ma) with respect to the North American craton that cannot be reconciled with offset along known faults (e.g. ~430 km, on the Tintina Fault). This has lead to suggestions that large translations are hidden or unrecognized within strata of the Selwyn Basin which forms the outermost part of the miogeocline in the northern Canadian Cordillera.

The idea that young large displacements can be shuffled cratonward of known large faults is irreconcilable with many features within the Selwy Basin region including: a) details of facies distribution within several formations collectively ranging from Cambrian to Late Triassic age, b) the configuration of the basin-to-platform (Selwyn Basin to Mackenzie Platform) boundary at various times, c) the distribution of mid-Cretacous intrusive suites, d) the age and style of Mesozoic fold and thrust belt deformation, e) the lack of any mapped structures which could possibly carry such signficant displacement, and f) the lack of topographic expression or ancillory features (local volcanics, small pull-apart bsins) that might be associated with such a young fault.

Clearly, paleomagnetic results from the Carmacks Group and their implied large, relatively young terrane displacements in the northern Canadian Cordillera remain a conundrum.