NEW PERSPECTIVES ON THE ORDOVICIAN-SILURIAN STRATIGRAPHY OF THE CLEMENTS MARKHAM AND NORTHERN HEIBERG FOLD BELTS, CANADIAN ARCTIC ARCHIPELAGO (Invited Presentation)

The Clements Markham and Northern Heiberg fold belts are volcanic-sedimentary subprovinces of the Franklinian mobile belt that crop out between the Pearya terrane to the north and Laurentian parautochthon to the south. Paleozoic rocks within these fold belts have uncertain origins, but some existing scenarios involve: (1) Ordovician arc-related origins between Pearya and the Franklinian margin; (2) Ordovician arc-related origins along the Iapetan margin, with later transport from NE Laurentia to Ellesmere Island by strike-slip faulting; and (3) Silurian continental arc-related origins along the Franklinian margin. New studies of Ordovician-Silurian strata in the Kulutingwak Fiord region of Ellesmere Island and Svartevaeg Cliffs of Axel Heiberg Island were initiated in 2017 to investigate these scenarios and test hypotheses for circum-Arctic tectonics.

The Kulutingwak Fiord region includes Ordovician lava flows, tuffaceous rocks, and marble of the Kulutingwak Formation, and slivers of undated serpentinite-bearing conglomerate and sandstone of the Phillips Inlet Formation. Our working hypothesis calls for Phillips Inlet detritus to have provenance from serpentinized rocks assigned to Pearya (e.g. Thores Suite) that were exhumed during the M’Clintock orogeny or a later event. Kulutingwak volcanism may be broadly related to the Iapetan convergent margin if Pearya restores to NE Laurentia in pre-Late Ordovician time. Silurian flysch that overlies the Kulutingwak Formation contains 970-1650 Ma detrital zircon crystals that were sourced from Pearya and the northern Caledonides to the north and east.

In the Northern Heiberg fold belt, the Svartevaeg Formation includes a lower succession of undated lava flows, comagmatic dikes, and volcanic conglomerate, and an upper succession of lower Silurian shale and lithic sandstone. New results show that correlative Fire Bay Formation strata on Ellesmere Island yield early Silurian zircons with radiogenic Hf isotope compositions (initial εHf = +5 to +8). If the Silurian continental arc hypothesis is correct, the Svartevaeg-Fire Bay magmatic system did not assimilate significant amounts of Laurentian basement. Silurian magmatism in the Northern Heiberg fold belt apparently ceased after the regional influx of Wenlock flysch along the northern Laurentian margin.