Multi-phase folding, Boyne Limestone

NE Scotland

These thinly bedded, greenish grey and cream units of the Boyne Limestone Formation (Argyll Group) were deposited in a shallow marine setting and later folded during the Caledonian Orogeny (390-490 Mya). The Caledonian Orogeny deformed and metamorphosed large tracts of Europe, America and North Africa; this small outcrop (c. 100cm x 25cm x 25cm) near Portsoy, NE Scotland, records some of this deformation at a macro scale.

Complex fold patterns are recorded in these thin interbeds of calc-silicate rocks, metalimestones and calcareous semipelites of Neoproterozoic age (541-1000 Mya). The dominant folding pattern here is associated with a third phase of Caledonian deformation (D3) which overprints an earlier D1 phase, resulting in fold interference patterns which can be seen on some surfaces.

 

Lat: 57° 40' 56"N, Long: 2° 38' 37"W