Late Paleozoic to Triassic Arc Magmatism North of the Sverdrup Basin in the Canadian Arctic: Evidence from Detrital Zircon U-Pb Geochronology

Tectonic reconstructions of the Arctic during the Paleozoic and Mesozoic have been a major subject of debate in recent years. The Permian emergence of a landmass north of the Sverdrup Basin in the Canadian Arctic led to the onset of northerly derived detritus and followed volcanism and basin inversion pulses that began in the latest Carboniferous. However, the mechanisms for these events and the Paleozoic - Mesozoic paleogeography of this region remain controversial. New LA-ICP-MS detrital zircon U-Pb geochronology data of late Paleozoic to Early Triassic units of the Sverdrup Basin help constrain the nature of this northern landmass and its effects on the adjacent basin. Permian to earliest Triassic strata of the northern margin of the Sverdrup Basin contain abundant zircons derived from Ellesmerian bodies (355 - 420 Ma), Timanian basement (500 - 700 Ma), and additional Permian syn-depositional sources (250 - 300 Ma). This signature differs from coeval strata in the southern margin, which are dominated by Ellesmerian and Caledonian aged zircons. The detrital zircon signatures of the studied units in the northern margin of the Sverdrup Basin record continuous magmatism within the northern landmass from latest Carboniferous (ca. 300 Ma) to at least earliest Triassic time (ca. 250 Ma). These results are indicative of ongoing subduction and development of a magmatic arc off the northern margin of the Sverdrup Basin. The proposed onset of subduction in latest Carboniferous time provides an explanation for the shift in stress regimes in the Sverdrup Basin that led to basin inversion and volcanism episodes. Therefore, the data in here presented suggests that the tectonic history of the Canadian Arctic during this time was controlled by an active margin regime, contrasting with previously accepted reconstructions and thus furthering our understanding of the tectonic evolution of the Arctic.