Pre-Nuna supercontinent reconstruction: the role of the global Arrowsmith Orogeny and its impact in western Canada

Introduction The great interest in supercontinent reconstructions reflects the importance of the supercontinent cycle in understanding global plate tectonic processes and its influence on formation and preservation of ore deposits. In spite of the substantive progress that has been made in reconstructing Earth’s younger supercontinents (e.g. Rodinia, Gondwana, Pangea), the number and possible makeup of supercontinents prior to the first known supercontinent Nuna, at 1.8 Ga, remain poorly understood. Traditionally the western Churchill Province (wCP,) was thought to have been part of Kenorland, a single supercontinent that amalgamated pre-2.6 Ga, was stable ca. 2.5 – 2.1 Ga and broke up by 2.1 Ga . The recent identification of the. 2.5 – 2.3 Ga Arrowsmith orogen on the western flank of the wCP (Berman et al., 2005) offers a very different picture for what has been considered a quiescent period, possibly linked to a plate tectonic shutdown on Earth (Condie et al., 2009). Here we present new geochronological data that provide important support for a broader distribution of the Arrowsmith orogen and review its possible global extent. Global recognition of this relatively uncommon period of orogenesis apparently negates the tectonic shutdown hypothesis and will provide a useful piercing point to explore pre-Nuna supercontinent reconstructions.