Paleocene alkaline volcanism in the Nares Strait region: evidence from volcanic pebbles

Abstract

Paleogene sediments in fault-bounded basins on Judge Daly Promontory, northeast Ellesmere Island, Canadian High Arctic, are rich in volcanogenic material. Volcanic pebbles within the Cape Back basin near Nares Strait were studied for their petrography, geochemistry, Sr and Nd isotopes, and geochronology to identify and characterize their parent rock. The pebbles are derived from lava flows and ignimbrites of a continental rift-related, strongly differentiated, highly incompatible element enriched, alkaline volcanic suite, the proposed Nares Strait volcanic suite, which is distinct from other alkaline volcanic suites on the northern coasts of Ellesmere Island and Greenland. 40 Ar/ 39 Ar amphibole and alkali feldspar ages indicate that volcanism was active around 61-58 Ma and was probably contemporaneous with sedimentation resulting in Middle to Late Paleocene age for deposition within the Cape Back basin and the other Paleogene basins on Judge Daly Promontory.

Multistage Cretaceous magmatism in the northern coastal region of Ellesmere Island and its relation to the formation of Alpha Ridge – evidence from aeromagnetic, geochemical and geochronological data

“…Whereas the mildly alkaline magmatism of northern Ellesmere Island (c. 96-75 Ma) is genetically closely related with the formation of the passive margin of the Alpha Ridge segment of the Amerasia Basin as discussed above, the Late Cretaceous alkaline magmatism of North Greenland and the Nares Strait region is interpreted as initial continental rifting related to the formation of the Eurasia Basin and movements along a temporary plate boundary between North America and Greenland (e.g., Estrada et al, 2010;Tegner et al, 2011;Thórarinsson et al, 2015). However, E-W extension in North Greenland might have caused reactivation of NE-SW-striking fault zones in northern Ellesmere Island, even accompanied by new igneous activity (e.g., Soper & Higgins, 1991;Piepjohn & von Gosen, 2001).…”

“…The HALIP includes continental flood basalts, mafic dykes and sills emplaced at the Barents Shelf region, De Long Islands, North Greenland, and the Canadian Queen Elizabeth Islands between c. 130 and 80 Ma (recently summarised by Buchan & Ernst, 2006;Nejbert et al, 2011;Tegner et al, 2011;Senger et al, 2014;Polteau et al, 2016;Thórarinsson et al, 2015). Late Cretaceous to Palaeogene, alkaline, mafic to felsic suites are known in North Greenland and in the Canadian Arctic (e.g., Dawes & Soper, 1970;Batten et al, 1981, Brown et al, 1987Embry & Osadetz, 1988;Estrada et al, 2010). Their genetic relationship to the older, dominantly tholeiitic suites is still under debate Estrada, 2015).…”

“…However, Late Cretaceous mildly alkaline magmatism that started in northern Ellesmere Island at c. 96 Ma (Estrada, 2015) is not recorded in the central Sverdrup Basin. alkaline volcanism on northeast Ellesmere Island that is recorded by volcanic pebbles with Ar-Ar ages of 61-58 Ma, which form part of the clastic infill of Palaeogene pull-apart basins along the Canadian side of Nares Strait (Estrada et al, 2010).…”

Origin of Bentonites and Detrital Zircons of the Paleocene Basilika Formation, Svalbard

“…The extrusion of the alkaline suite of the HALIP is typical for continental rifts and does only partly overlap geographically with the tholeiitic suite (Tegner et al, 2011). Alkaline mafic to felsic volcanism is known from northwest Ellesmere Island (Hansen Point Volcanic Complex at around 80 Ma; Embry and Osadetz, 1988;Estrada andHenjes-Kunst, 2004, 2013), the Kap Washington Group in North Greenland (71-61 Ma; Tegner et al, 2011;Thorarinsson et al, 2011a,b), from the Cape Back Basin on Ellesmere Island, evidenced by deposition of volcanogenic detritus (61-58 Ma; Estrada et al, 2010) and from Freeman Cove, Bathurst Island (56 Ma; Day et al, 2005; Figure 1). …”

“…Detailed timing of Eurekan deformation is still poorly constrained, but presumably commenced in the Paleocene, culminated in the Eocene, and may have lasted into the Oligocene (Tessensohn and Piepjohn, 2000;Piepjohn et al, 2013). Concurrent with Eurekan compression, extension prevailed further north, leading to the onset of spreading along the Gakkel Ridge, separation of the FIGURE 1 | Overview over the tectono-magmatic framework of the Arctic and North Atlantic oceans indicating two major magmatic phases expressed in the late Cretaceous high arctic large igneous province (HALIP) and the Paleocene-Eocene North Atlantic volcanic province (NALIP) as well as the widespread occurrence of Paleocene to Eocene ash deposits (compiled from Knox and Morton, 1988;Hopper et al, 2003;Larsen et al, 2003a;Storey et al, 2007;Estrada et al, 2010;Tegner et al, 2011;Reinhardt et al, 2013, and references therein).…”