Eruption age of the Sverrefjellet volcano, Spitsbergen Island, Norway

Eruption age of the Sverrefjellet volcano, Spitsbergen Island, Norway

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Sverrefjellet is a Pleistocene-age basaltic volcanic construct on north-western Spitsbergen Island (Svalbard Archipelago, Norway).Published ages for the Sverrefjellet eruption range between 6000 years and ca.1 million years before present.The age of eruption is dated here as 1.05±0.

07 (1σ) My, consistent with Ar–Ar isochron and plateau ages of several drive analysed samples.Radiogenic Ar represents a small proportion of the released Ar, <15% in nearly all samples.Non-radiogenic Ar components include air, excess 40Ar (seen as inverse isochron intercept values >40Ar/36Ar = 295.5), low-temperature alterations (Ar release at low temperature, with high Cl/K), carbonates and zeolites (Ar release at intermediate temperature) and xenolithic material (Ar release at high temperature, high Ca/K).The effects of the largely non-radiogenic argon sources are TEA TREE also seen in the total-gas Ar–Ar “ages”, which range from 1.

3 to 10.3 My, significantly larger than the inferred eruption age.It is likely that total-gas Ar–Ar “ages” and whole-rock K–Ar “ages” of similar basalts also exceed their true eruption ages.To access the supplementary material to this article please see Supplementary files under Article Tools online.