Late Ediacaran-early Cambrian rifting along the northern margin of Laurentia: constraints from the Yelverton Formation of Ellesmere Island, Canada

Neoproterozoic to early Paleozoic strata exposed along the northeastern margin of North America (Franklinian Basin) record a prolonged history of rifting and passive margin development. An episode of Ediacaran-Cambrian extension is potentially recorded in volcanic and sedimentary rocks of the Yelverton Formation, exposed on northern Ellesmere Island, Nunavut, Canada. Here, we present new whole-rock trace element and isotope geochemistry and hornblende 40Ar/39Ar geochronology from intrusive and extrusive rocks of the Yelverton Formation, along with isotope geochemistry from carbonate rocks under-lying the volcanics and detrital zircon U-Pb and Lu-Hf isotopic data from the Yelverton Formation and overlying Grant Land Formation. The carbonate strata yielded an average 87Sr/86Sr value of 0.7076 (n = 6), constraining the overlying volcanics to the late Ediacaran-early Cambrian (ca. 570-530 Ma). Flows and dikes/sills show three distinct compositions: (1) a depleted, low La/YbPM and Th/Nb group, (2) an enriched, higher La/YbPM and low Th/Nb group, and (3) a low to moderate La/YbPM and high Th/Nb group. One of the high Th/Nb intrusions produced saddle-shaped 40Ar/39Ar hornblende spectra with ca. 482 +/- 7 Ma age minima and Silurian-Devonian inverse isochron ages, highlighting a hitherto unknown suite of younger intrusions and volcanic rocks. The trace element geochemistry and 143Nd/144Nd(t) ratios of enriched and depleted volcanic rocks of the indisputable Yelverton Formation are consistent with decompression melting during rifting along a continental margin. We suggest that late Ediacaran-early Cambrian rifting recorded in the Yelverton Formation resulted in the separation of peri-Laurentian terranes, such as the North Slope subterrane and eventual development of the passive margin of northern Laurentia.