Rubidium–strontium Ages from North-East Land (Spitsbergen)

Abstract

Hamilton, Harland and Miller¹ have shown that igneous and metamorphic rocks from West Spitsbergen indicate Caledonian ages, which are consistent writh stratigraphic, structural and petrological evidence. A vast thickness, probably more than 15 km, of Precambrian to Lower Palæozoic sediments (Hecla Hoek) are consistent with a picture of a geosyncline². Less than 20 miles to the east the adjacent island of North-East Land (Nordauslandet) consists of undeformed crystalline basement overlain by only 4–5 km of Hecla Hoek sediments. In some areas deeper parts of the basement are exposed in anticlines, while the adjacent synclines contain folded sediments. Sandford^3,4 concluded from stratigraphical and structural evidence that an unconformity is present between the sediments and the basement, and that intrusive granodiorites occur in the lower part of the sediments. Either an unconformity exists between the Hecla Hoek sediments and the crystalline basement or there has been continuous deposition to the Lower Palæozoic (compare with ref. 5), in which igneous activity is only related to the deeper part of the sedimentary pile.