Eruption age of the Sverrefjellet volcano, Spitsbergen Island, Norway

Abstract

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 the eruption is dated here as 1.05±0.07 (1s) My, consistent with Ar-Ar isochron and plateau ages of several 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 is also seen in the total gas Ar-Ar “ages,” which range from 1.3 – 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.

Keywords: Svalbard; Spitsbergen; basalt; Knipovich; Ridge; Ar-Ar

(Published: 2 March 2012)

Citation: Polar Research 2012, 31, 17320, DOI: 10.3402/polar.v31i0.17320

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