Late Cretaceous bimodal magmatism,northern Ellesmere Island:isotopic age and origin

Abstract

In the Yelverton Bay region of northwestern Ellesmere Island, bimodal intrusive and volcanic rocks are associated with a major fault in the Proterozoic–Cambrian rocks of the Pearya Terrane. The Wootton intrusion consists mainly of gabbro with lesser amounts of granitic and hybrid rocks; the Hansen Point volcanics are composed of felsic rocks and basalt. Plutonic zircons are very slightly discordant, but volcanic zircons have unusually high degrees of inheritance. Interpreted U/Pb zircon ages of 92.0 ± 1.0 Ma for the Wootton intrusion (assuming a wide range of inheritance ages) and of [Formula: see text] for the Hansen Point volcanics are close to the 93 Ma average of hornblende K/Ar dates obtained earlier for a small quartz diorite pluton in central northernmost Ellesmere Island. All fall into the early Late Cretaceous and indicate correlation with mafic volcanics of the Cenomanian–Turonian Strand Fiord Formation of eastern Axel Heiberg Island. The upper intercept age for the Hansen Point volcanics ([Formula: see text]) suggests that the felsic component in the bimodal suites was in part derived from the upper Middle Proterozoic (Neohelikian) basement gneiss. Limited field observations on the Wootton intrusion also are compatible with the hypothesis that the granitic component represents sialic basement, melted by mafic intrusion at depth during an extensional tectonic regime.

Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province

“…Among the best known is the Wootton Instrusive Complex in the northern part of Ellesmere Island (Estrada et al 2006), where gabbro and minor amounts of granite have been recognized. The UÁPb ages of zircons separated from these plutonic rocks are 93 and 92 My (Trettin & Parrish 1987 Vincenz et al (1981Vincenz et al ( , 1984 and also partly with the first radiometric data (110Á149 Mya), presented by Gayer et al (1966). A preliminary dating of basalts and dolerites from Kong Karls Land using the ArÁAr method (Grogan et al 2000) has yielded 130Á100 Mya for these rocks, which is in good agreement with the results presented in this study.…”

Evidence for Extreme Climatic Warmth from Late Cretaceous Arctic Vertebrates

“…These data indicate an age of 95.3 Ϯ 0.2 Ma near the CenomanianTuronian boundary (13). U/Pb zircon analyses of gabbroic intrusions on northwestern Ellesmere Island, thought to be part of the same magmatic event as that represented by the Strand Fiord Formation, yield an age of 92.0 Ϯ 1.0 Ma (early Turonian) (14). Together these data indicate that the vertebrate fossil assemblage is Turonian to Coniacian (ϳ92 to 86 Ma) in age.…”

“…In addition to volcanism in the Arctic, basaltic volcanism occurred at five large igneous provinces during Turonian-Coniacian times, including (Fig. 4) emplace- Ar radiometric age data from the Strand Fiord Formation (this work) and Pb/U radiometric age data from gabbroic intrusions on Ellesmere Island (14). Ar recoil is suggested by the discordance pattern at low temperature steps.…”

The High Arctic LIP in Canada: Trace element and Sm–Nd isotopic evidence for the role of mantle heterogeneity and crustal assimilation

“…Embry & Osadetz (1988 100 C.G. Kingsbury et al clarifying and constraining ages from earlier K-Ar and Ar-Ar studies and yield evidence of magmatic activity between 121-126 Ma and ~92 Ma (Trettin & Parrish, 1987;Corfu et al, 2013;Estrada & Henjes-Kunst, 2013;Evenchick et al, 2014Evenchick et al, , 2015map compilation, geochemistry, geo chronology, and potential field data to document six intervals of Cretaceous magmatism in the central Sverdrup Basin. These are: 1.…”

“…In addition to the 120-125 Ma pulse of magmatism scattered about the Arctic Margins, a younger episode of mafic magmatism ensued approximately 30 myr later, largely affecting the Canadian side of the Arctic Ocean. Two separate studies on the gabbroic and microgranitic Wootton Igneous Complex, located along the extreme northern Ellesmere Island coast, yielded U-Pb ages of 92.0 ± 1.0 Ma (Trettin & Parrish, 1987) and 92.1 ± 0.1 Ma (Estrada & HenjesKunst, 2013) on the gabbroic component, as well as 92.7 ± 0.3 Ma on three microgranite samples (Estrada & Henjes-Kunst, 2013). …”