A palaeomagnetic and geochemical study of basic intrusions in northern Sweden

• A palaeomagnetic and geochemical study has been performed on basic dykes in northern Sweden. The dykes and a gabbro formation were sampled in 28 sites and characteristic magnetizations could be defined in 23 of them. The dykes form a part of a swarm that trends in NE-SW to E-W. From differences in palaeomagnetic signatures and composition it is concluded that this swarm is composed of two generations of dykes, group A and B, trending in similar directions. The dykes of group A have compositions that are similar to rapakivi related dykes, while those of group B are different from most rapakivi dykes in Fennoscandia. The calculated pole positions may suggest that the group B dykes are older than those of group A and both groups intruded within the time span 1.77 Ga to 1.50 Ga. The trend of the dykes is more or less parallell to a palaeo-compressional stress field that may be expected from the collisional tectonics related to the Gothian orogeny. The intrusion of the rapakivi formations in Fennoscandia has been suggested to be related with the Gothian orogeny and the intrusion of the dykes may thus be guided by the stress field generated by the collisional tectonics.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geofysik (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geophysics (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geology (hsv//eng)

Nyckelord

Tillämpad geofysik

Applied Geophysics

Malmgeologi

Ore Geology

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