Palaeomagnetism of the Svecofennian Loftahammar gabbro and some Jotnian dolerites in the Swedish part of the Baltic Shield

Abstract

The Svecofennian Loftahammar gabbro (RbSr isochron age 1,694 · 10 6 year) and Jotnian dolerites (KAr isochron age 1,245 · 10 6 year) in Sweden were found to have palaeomagnetic pole positions in close agreement with poles from other Svecofennian rocks in Sweden and Jotnian dolerites in Finland, respectively. These results support Neuvonen's apparent polar wandering path during the period from 1,900 · 10 6 to 1,300 · 10 6 year. A reconstruction of the position of the Baltic Shield during the (1,900-1,200) · 10 6-year interval, based on available pole positions, indicates that the Baltic shield was close to Greenland and the North American Shield and reveals a contiguity of North Atlantic geologic-geochronological zones until 1,200 · 10 6 year ago.