The migmatite complex near Lyngdal, Southern Norway, and related granulite metamorphism

Geological mapping in the migmatite complex near Lyngdal has demonstrated the significance of major rock units, designated lithostructural formations, as principal divisions of the complex. Conformable granitic gneisses and banded gneiss series form the oldest part, in which augen gneisses apparently developed by partial anatexis and feldspar blastesis prior to deformation. Late granitic intrusions finally transgress the polyphase folded complex. The metamorphic environment is high-grade, showing transition between upper amphibolite and granulite facies. Three metamorphic zones are recognized where the isogrades Hy-in and Hbl-out indicate increasing metamorphic grade towards south. Mineral assemblages suggest total pressures in the order of 6-7 Kbar and a regional temperature between 700° and 800°C.