Workreport 2007-22



Preliminary Paleomagnetic Study on Different Rock Types in Olkiluoto Area


Mertanen, S.



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Paleomagnetic test samples have been measured from different rock types in the Olkiluoto area. The main aim of the study has been to resolve the suitability of the rock types to paleomagnetic studies. Paleomagnetic studies are aimed to investigate the geological evolution of the Olkiluoto area by using remanent magnetization that has been blocked in the rocks in different geological processes.

Altogether 20 cylinders were measured from five different rock types. The cylinders were demagnetized with alternating field and the remanent magnetizations were measured. The results were analysed with multicomponent analysing methods.

According to preliminary studies, most of the test samples are weakly magnetized and do not carry stable remanent magnetization. However, part of the samples and rock types carry stable or semistable remanent magnetizations and are therefore favourable for further investigations. Especially the diabase dykes carry stable multicomponent magnetizations. Also the pegmatite dykes are worth of additional studies. Remanent magnetizations of test samples from TGG-gneisses, potassium feldspar porphyries and sulphidized rocks are weaker, but it is suggested that some new test samples would be useful for further studies.


paleomagnetism, remanent magnetization, Olkiluoto, Finland


Preliminary Paleomagnetic Study on Different Rock Types in Olkiluoto Area (pdf) (207.8 KB)


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