Geological map of high-grade gneisses in the northern Vestfold Hills

The gneisses are described relative to a simple structural framework dominated by two regional high-grade deformation episodes (D1 and D2), according to whether gneisses were affected by D1, or intruded in the D1 to pre- or syn-D2 interval.

The oldest gneisses are volumetrically minor metasedimentary (Taynaya and Chelnok Paragneisses) and metabasic (Tryne Mafic Gneiss) units that were intruded by pre-D1 felsic magmas (Mossel Gneiss protolith). These units were folded and interleaved during a regional high-grade deformation event (D1-M1), and subsequently intruded by regionally extensive and compositionally diverse magmas gneisses and Crooked Lake group protolith).