Preliminary observations on the palaeomagnetism and radiometric ages of the Tertiary basalt sequence of Scoresby Sund, East Greenland

Abstract

During the 1972 summer field season a detailed sampling programme was undertaken on the Tertiary basalt sequence on the south side of Scoresby Sund, East Greenland, with the view to obtaining a systematic collection of orientated samples for palaeomagnetic work. Additional samples were collected from key localities for radiometric age determinations. A previous palaeomagnetic pilot-study of a limited number of samples from the Tertiary lavas of this region by Tarling (1967), indicated the presence of a moderately stable remanent magnetisation, which was reversed with respect to the Earth's present magnetic fieid. The present work has been undertaken in the hope that a detailed study of the remanent magnetisation of the whole sequence might reveal changes in polarity which could be used for correlation purposes. The establishment of a polarity reversal sequence in these lavas has been attempted previously by Watt & Watt (1971), on the basis of the direct measurement of magnetic polarity in the fieid, using a hand compass. In order to check the reliability of such field polarity determinations, a portable fluxgate magnetometer was used to make slightly more accurate direct measurements, which could subsequently be compared with the much more precise results obtained from laboratory measurement of the carefully orientated samples.