“… Figure 1. Shaded relief bathymetry map showing major geographical features of the Arctic region. Areas encompassed by dashed lines identify occurrences of HALIP magmatic rocks (Maher, 2001; Buchan and Ernst, 2006; Drachev & Saunders, 2006; Gaina et al 2013; Verzhbitskii et al 2013). Solid lines schematically indicate major HALIP-related dyke swarms of the Queen Elizabeth swarm in the Canadian Arctic islands and on Franz Josef Land (after Buchan & Ernst, 2006; Døssing et al 2013).…”
U–Pb ages of zircon from bentonites within the upper Cretaceous Bastion Ridge and Kanguk formations, Sverdrup Basin, provide constraints on sedimentation rates, biostratigraphic correlations, timing of Oceanic Anoxic Event 2 (OAE2) in the High Arctic, and the late magmatic history of the High Arctic Large Igneous Province (HALIP). A late Cenomanian to early Turonian age for the base of the Kanguk Formation is confirmed that supports correlations of the global OAE2 in the High Arctic. Sedimentation rates varied from 19 m Ma−1 between 93 and 91 Ma to 26 m Ma−1 between 91 and 83 Ma at Axel Heiberg Island. At Ellef Ringnes Island, the lower Kanguk Formation records high rates of ~70 m Ma−1 between 94 and 93 Ma, which decrease to rates comparable to those of the upper Axel Heiberg section. Differences in sedimentation rates may reflect differences in setting prior to the major transgression in the latest Cenomanian to early Turonian. The timing of Arctic occurrences of the Scaphites nigricollensis and Scaphites depressus ammonite zones is shown to be broadly comparable to that of lower-latitude occurrences within the Western Interior Seaway. An eruption frequency of 0.5–2.5 Ma characterizes the late alkaline phase of HALIP magmatism. Volcanic bed thicknesses of 10–50 cm suggest ash transport distances of less than 1000 km. Long-lived volcanic centres, in the area of the Alpha Ridge, northern Ellesmere Island or northern Greenland, were the likely source of volcanic ash over a period of 10–15 Ma.
“… Figure 1. Shaded relief bathymetry map showing major geographical features of the Arctic region. Areas encompassed by dashed lines identify occurrences of HALIP magmatic rocks (Maher, 2001; Buchan and Ernst, 2006; Drachev & Saunders, 2006; Gaina et al 2013; Verzhbitskii et al 2013). Solid lines schematically indicate major HALIP-related dyke swarms of the Queen Elizabeth swarm in the Canadian Arctic islands and on Franz Josef Land (after Buchan & Ernst, 2006; Døssing et al 2013).…”
U–Pb ages of zircon from bentonites within the upper Cretaceous Bastion Ridge and Kanguk formations, Sverdrup Basin, provide constraints on sedimentation rates, biostratigraphic correlations, timing of Oceanic Anoxic Event 2 (OAE2) in the High Arctic, and the late magmatic history of the High Arctic Large Igneous Province (HALIP). A late Cenomanian to early Turonian age for the base of the Kanguk Formation is confirmed that supports correlations of the global OAE2 in the High Arctic. Sedimentation rates varied from 19 m Ma−1 between 93 and 91 Ma to 26 m Ma−1 between 91 and 83 Ma at Axel Heiberg Island. At Ellef Ringnes Island, the lower Kanguk Formation records high rates of ~70 m Ma−1 between 94 and 93 Ma, which decrease to rates comparable to those of the upper Axel Heiberg section. Differences in sedimentation rates may reflect differences in setting prior to the major transgression in the latest Cenomanian to early Turonian. The timing of Arctic occurrences of the Scaphites nigricollensis and Scaphites depressus ammonite zones is shown to be broadly comparable to that of lower-latitude occurrences within the Western Interior Seaway. An eruption frequency of 0.5–2.5 Ma characterizes the late alkaline phase of HALIP magmatism. Volcanic bed thicknesses of 10–50 cm suggest ash transport distances of less than 1000 km. Long-lived volcanic centres, in the area of the Alpha Ridge, northern Ellesmere Island or northern Greenland, were the likely source of volcanic ash over a period of 10–15 Ma.
New characteristics and generalized geostructural, isotope-geochronological, and paleomagnetic data are presented for the first time for the territory of Jeannette Island in the De Long Archipelago. Until recently, this small rock outcrop in the East Siberian Sea, discovered in the late 19th century, has been in effect a blank spot on the geological map. Field work made in 2013 and subsequent laboratory analysis of the obtained sample collection show that the island has a volcanogenic-sedimentary section including many thin (up to several meters) dolerite dikes. These dikes are the main target of the study. Newly obtained 40Ar/39Ar isotope-geochronological data indicate that the earliest dike intrusion stage corresponds to the Ediacaran (553.6 ± 10.3 Ma). Several subsequent tectonothermal events can be inferred until and through the Early Carboniferous, which affected the stability of the isotope system in the dolerites. In addition, paleomagnetic data confirm at least one more stage of dike emplacement, in the Early Ordovician, as the coordinates of the virtual geomagnetic poles for the dikes are nearly identical to those of the Ordovician paleomagnetic pole determined for carbonate rocks of Kotelny Island. The study describes the main petromagnetic characteristics and magnetic mineralogy of the studied dolerites, validating the primary thermoremanent nature of the identified characteristic component. The results agree with available information on the paleomagnetism, tectonics, and paleogeography of the New Siberian Islands.
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