Stratigraphy and Geochemistry of Lower Permian volcanics in the Sverdrup Basin, Northwest Ellesmere Island, Nunavut.

摘要

Five sections of Lower Permian mafic volcanics were examined on northwest Ellesmere Island in the Sverdrup Basin, Arctic Canada. Detailed field work shows that two stratigraphic levels exist; the lower level is an unnamed volcanic unit that occurs in a Sakmarian-Artinskian succession, and the upper level is a mappable unit, the Esayoo Formation, which occurs in a Kungurian succession. Within the regional upper Paleozoic sequence stratigraphy the volcanics are contemporaneous with transgressive systems tracts.;Petrographically, these volcanics are spilites. Trace element chemistry illustrates patterns similar to ocean island basalts. Tectonic discriminant diagrams show affinities to within plate basalts, with alkaline to transitional basalt affinities. Sm-Nd isotopic analyses suggest the Esayoo Formation is sourced from an enriched mantle, with 3tNd values that range from -3.99 to -5.87. Trace element ratios reveal an enriched mantle type I (EMI) source. In addition these volcanic occurences are synchronous with coeval compressional-extensional tectonic pulses associated with the Melvillian Disturbance.