Buchan type metamorphism, Aberdeenshire
Scotland
Do not miss the type locality for Buchan type metamorphism along the northern coast of Aberdeenshire.
Sebastian Fischer
Apart from the beautiful scenery and the numerous distilleries in nearby Speyside, this area also has some geological treats to offer. In the rocks in this areas you can see evidence of the Buchan metamorphic facies. The metamorphism seen in these rocks is caused by a rapid increase in temperature but a relatively small increase in pressure. Characteristic minerals of this type include andalusite, biotite and cordierite. This type of metamorphism usually occurs in ‘extensional’ settings such as a rift basin.
There is a particularly spectacular section exposing the Buchan Metamorphic zoning betwee Macduff and Portsoy which shows spectacular geology. One can nicely observe the progression from largely unmetamorphosed turbidites (with very nice graded bedding) to high-Temperature (at comparatively low-Pressure) metamorphism including partial melting.
Above are pictures of the low grade turbidites at the eye of the needle in Macduff (biotite-zone), cordierite-porphyroblasts at Banff (cordierite-zone), and andalusite & staurolite porphyroblasts at Whitehills (Boyndie Bay beach).
Text: Sebastian Fischer
Nominated by: Sebastian Fischer (Facebook)