The Sverdrup Basin Magmatic Province in the east-central Sverdrup Basin is an Early Cretaceous to Paleogene large igneous province. It consists of pyroclastic deposits, thin lava flows, flood basalts and central volcanoes, as well as hypabyssal sills and dikes. Argon–argon dating of mafic igneous rocks from the province suggests that mafic magmatism peaked during two time intervals. The first time interval between 127 and 129 million years ago was characterized by the widespread intrusion of sills and dikes. Flood basalt volcanism during the second time interval between 92 and 98 million years ago was coeval with the development of the proto-Arctic Ocean. Sills and flood basalts of the Sverdrup Basin Magmatic Province are well-exposed in the Princess Margaret Range, a north–south trending mountain range extending across the length of Axel Heiberg Island. Basaltic lava flows occur in the Isachsen and Strand Fiord formations. Sills intrude the entire Mesozoic succession and are particularly abundant in the Triassic shales of the Blaa Mountain Group.
