Palaeozoic palaeomagnetic results from Scotland and their bearing on the British apparent polar wander path

Abstract

Palaeomagnetic studies of the Lower and Upper Old Red Sandstone (ORS), western Midland Valley, indicate the presence of two principal remanence components, IB and HB. Both components can be demonstrated to be of secondary, post-Upper ORS, origin. Component IB compares with palaeomagnetic results from Upper Carboniferous/Permian dykes and sills in the Midland Valley, whereas HB conforms to palaeomagnetic results from the overlying Lower Carboniferous Lavas. A combination of HB components from the Lower/Upper ORS and Lower Carboniferous lavas (western Midland Valley) yields a relative pole position near S14 and E322 which compares well with Lower Carboniferous data from the Kinghorn and Burntisland Lavas, eastern Midland Valley (S14 and E332). From Kinghorn, the palaeomagnetic data can be demonstrated to be of primary, Lower Carboniferous, origin. Seen in conjunction with the British polar wander path, the Lower Carboniferous poles reported here seemingly dissociate Middle-Upper Devonian and Upper Silurian/Lower Devonian poles. Owing to the lack of magnetic age control in the Middle-Upper Devonian data base, it is argued that the majority of Middle-Upper Devonian data from the British Isles should be reconsidered as Carboniferous magnetic overprints. This carries the implication that any tectonic models based on Middle-Upper Devonian palaeomagnetic results should be considered highly suspicious.