Polsko-amerykańskie badania paleomagnetyczne na Spitsbergenie w latach 1971-1977

Krzysztof Birkenmajer



As a result of Polish-American co-operation between the Institute of Geophysics, Polish Academy of Sciences and the Department of Earth and Planetary Sciences, St. Louis University, two expeditions to Spitsbergen were sent in 1974 and 1977 - to Hornsund, south Spitsbergen and Agardhbukta, east Spitsbergen, respectively. The aim of the expeditions was to collect oriented samples for palaeomagnetic investigation of Spitsbergen rocks, mainly late Mesozoic dolerite intrusions (Fig. 1). The Hornsund dolerite dykes dated as 110 ±5 m.y. by K-Ar whole-rock method (8) gave a Lower Cretaceous (Aptian-Albian) palaeomagnetic pole position at 79.5°N-202.7°E. This palaeomagnetic pole is similar to Cretaceous (?late Cretaceous) pole positions for basaltic lavas of northern Spitsbergen (7). In the pre-drift configuration of continental plates of the Arctic, the late Mesozoic pole positions of Spitsbergen fall within the field of North-American Cretaceous poles (Figs 2A, B).
The dolerite dykes of Hornsund occur close to the Tertiary fold belt of Spitsbergen and were affected to some extent by Tertiary diastrophism which bad caused their partial remagnetisation. The dolerite sills of the Agardhbukta area, radiometrically dated as 110 ±5 m.y. (4) are undeformed or very slightly deformed, and occur far away of the Tertiary fold belt. It is hoped that they will supply palaeomagnetic data even more reliable than those of the Hornsund dykes.

Full Text:

PDF (Polish)