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Magnetostratigraphy of Palaeocene basalts from the Vaigat Formation of West Greenland |
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| Authors: | Peter Riisager & Niels Abrahamsen |
| Institution: | Department of Earth Sciences, Aarhus University, Finlandsgade 8, 8200 Aarhus N, Denmark,; Danish Lithosphere Centre, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark. E-mail: |
| Abstract: | A palaeomagnetic study comprising the directional results from 289 individual lava flows, sampled along eight sections in the Palaeocene basalts of West Greenland, is reported. The eight individual sections are correlated using lithostratigraphical marker horizons to form a single composite profile. Generally, the lithological correlation is in good agreement with the record of geomagnetic secular variation. The total composite palaeomagnetic profile represents a stratigraphic thickness of 1.6 km through the Vaigat Formation, which is the lowermost of the two volcanic formations formed during the main stage of plateau volcanism. Only two polarity zones are found in the composite profile, suggesting a very short duration for the West Greenland main plateau-building volcanism. The C27n–C26r transition is fully recorded along one of the sections (Nuusap Qaqqarsua), with intermediate directions covering a 200 m thick succession of lavas. A combined palaeomagnetic, field and geochemical study along this profile showed good agreement; that is, geochemically and geologically derived single magmatic events show groupings of the palaeomagnetic directions. Supposing a duration for the geomagnetic transition of 5000 years, the eruption frequency during this period was as high as one flow every 80 years. |
| Keywords: | geomagnetic reversal magnetostratigraphy Palaeocene palaeomagnetism West Greenland |