2 February 2018

Friday fold: 3D model from the Portsoy Shear Zone

Posted by Callan Bentley

Today’s Friday fold comes to us from the team at eRocK, a neat repository of structurally interesting 3D models. Their website describes the project this way:

eRocK is a virtual geology project led by Adam Cawood and Clare Bond at The University of Aberdeen. This project aims to provide open-source geological data and visualizations for fellow researchers, educational institutions and the general public. Our models are currently embedded into our own site via the free online viewer Sketchfab.

Though they have many lovely fold models, I picked this one because (1) it’s new, and (2) it has nice differential weathering of the sedimentary layers, resulting in a pleasing texture to the outcrop and the model derived therefrom. Enjoy spinning it around!

Adam describes this outcrop like this:

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 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

Happy Friday, all!