- journal_title：Journal of the Geological Society
- Contributor：G. J. Potts
- Publisher：Geological Society of London
- Date：1990-
- Format：text/html
- Language：en
- Identifier：10.1144/gsjgs.147.6.0999
- journal_abbrev：Journal of the Geological Society
- issn：0016-7649
- volume：147
- issue：6
- firstpage：999
- section：Article
Two geologically significant palaeomagnetic components have been isolated in samples of Torridon Group sandstones from the Kishorn nappe of NW Scotland. The samples were collected from the Eishort anticline, a large recumbent fold of Caledonian age. The softer component (which is demagnetized by low temperatures and weak magnetic fields), when in situ, displays a steep upward direction typical of reversed Tertiary magnetizations. Both polarities of the harder component (which is demagnetized by high temperatures only) are present and, when dip corrected, display either northwesterly upward or southeasterly downward directions characteristic of Torridonian remanences. It is suggested that the Tertiary component is of chemical origin and the result of alteration of magnetite (titanomagnetite) grains. The geographical distribution of these grains is irregular and as a result the distribution of the Tertiary overprint is irregular. The Torridonian palaeomagnetic components from both limbs of the fold can be restored by rotation about the fold axis to internally consistent directions which lie close to previously published data from the Caledonian foreland. No correction is necessary for finite strain which suggests that the Eishort anticline formed by a flexural slip mechanism. However, an anticlockwise rotation of 26° is required to reconcile the Torridonian directions from the Kishorn nappe with those of the Caledonian foreland which suggests that, during emplacement, the thrust sheet rotated on the underlying fault surface.