A magnetic study of tertiary igneous rocks from Greenland, Baffin Island and Iceland

Kristjansson, Leo Geir (1972) A magnetic study of tertiary igneous rocks from Greenland, Baffin Island and Iceland. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

This work describes paleomagnetic measurements carried out by the author on rock samples from Tertiary basalt areas in southern Disko Island (West Greenland), Cape Dyer (Baffin Island) and Iceland. -- In the Disko collection, the stable remanence direction of samples from 45 felsparphyric lava flows in three separate profiles was measured and shown to be that of the primary remanence in the flows. A mean ancient pole position at 62°N, 169°W was derived from 37 of these flows. A relatively large secondary component of remanence was shown to be viscous remanence acquired in situ during the present geomagnetic epoch. Correlations between these magnetizations and other magnetic characteristics of the flows were studied. -- The magnetic properties of several intrusive basalt units, a breccia, and local sediments, all from Disko Island, were also investigated. All formations were found to be reversely magnetized, but differences in these properties between and within the units were shown to be due to variations in oxidation state and in the rate of initial cooling. -- Similar studies were carried out on samples from 6 olivine basalt flows in Cape Dyer. Their remanence was very stable and of normal polarity; secondary magnetization components are small except in three samples from one flow, which are reversely magnetized and appear to have suffered remagnetization in situ, A mean pole position of 83°N, 55°W was derived from five of the Cape Dyer flows. -- Various magnetic properties of a number of rock samples from Iceland and from the Precambrian basement on the Baffin Bay coast were investigated, to aid in the geological interpretation of magnetic anomalies found in these areas. -- Two rock magnetic instruments, a thermomagnetic balance and a ballistic magnetometer, were designed, built and used during the present study and are described in detail.

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