High Resolution Paleomagnetism and Magnetostratigraphy of Ferrar Volcanic rocks from the Southern Mesa Range (North Victoria Land, Antarctica)

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Continental Flood Basalts (CFB) such as the Karoo-Ferrar province are interpreted as having been emplaced over continental areas in the order of 10 km and within a relatively short period of time of less than 1m.y. and therefore are often linked to mass extinctions. Whether the Karoo-Ferrar volcanic rocks of early Jurassic age meet the requirement of rapid extrusion has recently been debated and geochronological data suggests a longer duration of the volcanic activity of up to 6 m.y. If this longer period of emplacement is realistic than it becomes questionable whether the end- Plienbachian mass extinction is linked to the Karro-Ferrar CFB at all. Taking into account that the early Jurassic geomagnetic field displays extremely high reversal rates, any volcanic sequence which spans more than 1m.y. should record at least one, but probably more, reversals of the Earth magnetic field. It is therefore planned to study paleomagnetically the Kirkpatrick basalts of Mesa Range, Antarctica, where at least 40 volcanic flows are exposed in the Gair Mesa a sequence of up to 800m in height. Preliminary results of earlier studies suggest that there is a realistic chance to isolate primary magnetizations a notion being supported by the presence of unaltered glass in the ground mass which has been described for these rocks indicates the pristine conditions of these basalts. Our studies will be complemented by the determination of paleointensities. Taking into account that the paleointensity data base for the Mesozoic is extremely small, any contribution towards improvement of data density represents a great step forward to a better understanding geodynamo processes in the past.