A palaeomagnetic study of Jurassic rocks from the Antarctic Peninsula and its implications

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Abstract
Palaeomagnetic measurements have been made on rocks of Jurassic age from the Antarctic Peninsula to determine whether there has been relative movement between the region and East Antarctica. Samples were collected from the Oscar II Coast and the Cole Peninsula. Reliable results have been obtained from Jurassic dykes dated in one area at 174 ± 5 Ma, from an acid pluton of approximately the same age and from lavas of middle Jurassic age. Combining these results a position for the palaeopole was obtained at 48°S 238°E. If a reconstruction of Gondwana consistent with sea-floor spreading, palaeomagnetic and geological data is adopted, such as that of Norton & Sclater (1979), then a well-determined position for the Antarctic Peninsula within the reconstruction is obtained. Space considerations suggest that during the Jurassic the relative positions of the Antarctic Peninsula and the Ellsworth block were not very different from the present day, though palaeomagnetic measurements (Watts & Bramall 1981) indicates that the orientation was different.