Abstract

The tectonic evolution of the Connemara Gabbro Suite as deduced from careful tilt correction of the initial remanence directions, and interpretation of locally reset magnetizations is substantially in agreement with that based on purely geologic criteria. Fold tests of remanence suggest the gabbro bodies acquired their remanence after the F3 folding phase but before the F4, Connemara Antiform folding phase, sometime between 440–490 Ma. After unfolding both limbs of the antiform so that the remanences of the two limbs coincide, an antiformal structure still remains. Therefore, the F3 hinge surfaces were not coplanar at the time of gabbro intrusion, and the Connemara Antiform had already begun to develop before the members of the gabbro suite had had sufficient time to cool below the Curie point. During the development of the F4, localized remagnetization occurred at two particular periods.It was not possible to obtain a unique remanence direction by 'unfolding' the limbs of the F4 antiform about its eastward plunging axis; a virtual geomagnetic pole cannot be quoted. Much of current paleomagnetic research is aimed at defining paleopole positions, so that in cases where they are required extreme care must be exercised in applying geologically appropriate tilt corrections, and where more than one correction is required, they must be applied in the correct sequence.

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