Major shear zones and autochthonous Dalradian in the north-east Scottish Caledonides
The Buchan area within the Grampian Caledonides of north-east Scotland is a classic locality for the study of low-pressure regional metamorphism. Using detailed geophysical surveys, pits and boreholes to augment sparse outcrop data, we have revealed a system of steep shear belts of Grampian age. When combined with a reassessment of the stratigraphy, the new information leads us to the view that the Banff nappe does not exist. We also argue that the Tay nappe is of limited extent in Buchan, and that the tract of uninverted Southern Highland Group (upper Dalradian) is autochthonous.
A radiometric age for pegmatite cutting the Belhelvie mafic intrusion, Aberdeenshire
Synopsis A Rb-Sr isochron for four muscovites, one K-feldspar and one whole rock from pegmatites cutting sheared gabbro in the Belhelvie mafic complex yields an age of 477±5 m.y. and initial Sr87/Sr86 of 0.7185±0.0016. This age provides a minimum limit for all Late Caledonian deformation in the area. Evidence presented suggests that the Belhelvie pegmatites are part of a regional suite.
Garnitures mécaniques d'étanchéité
Keywords: etancheite ; mecanique Reference Record created on 2005-11-18, modified on 2016-08-08