Svartevaeg terrane: New evidence for a Silurian arc fragment in northern North America and its significance for early Paleozoic sinistral displacements along the Canadian Arctic transform system

The Canadian Arctic transform system defined a Paleozoic plate-boundary zone along northern Laurentia from the Svalbard Caledonides through Arctic Canada to eastern Alaska. Published models predict the early history of the Canadian Arctic transform system included Ordovician arc collision followed by Silurian reactivation of suture zone faults, sinistral translation of crustal fragments, and synorogenic flysch deposition. Here, we define the Svartevaeg terrane as a fault-bounded fragment in the northern Axel Heiberg and Ellesmere Islands region of Nunavut, Canada, and interpret its origin, displacement, and capture along the Canadian Arctic transform system. New igneous and detrital zircon U/Pb-Hf isotope and whole-rock geochemical results from the Svartevaeg Formation indicate the Svartevaeg terrane primarily consists of Silurian lava flow and volcaniclastic deposits that are the vestiges of an arc system. The new data allow three nonunique scenarios for the onset of Silurian arc volcanism: (1) Compressive stresses along a restraining bend forced oceanic lithosphere beneath northern Laurentia analogous to Puysegur subduction nucleation near the Australia-Pacific transform plate boundary, (2) postcollision convergence taken up by accreted Ordovician arc lithosphere led to a polarity reversal along northern Laurentia analogous to Ryukyu subduction nucleation near the Luzon arc−Eurasia collision, or (3) the Svartevaeg terrane had an outboard origin within a west-propagating island-arc system. Silurian−Devonian sinistral transpression resulted in arc cessation, deformation, and accretion of the Svartevaeg terrane along the Canadian Arctic transform system. Detrital zircon assessments of new and published flysch datasets constrain the initial juxtaposition and final imbrication of the Svartevaeg terrane against Laurentian margin successions at ca. 420 Ma and 360 Ma, respectively.