Early Migmatites in the Prograde Metamorphism Zone of Gneisses in the Northern Domain of the Ladoga Region: U-Pb Evidence Based on Monazite

摘要

The North Ladoga region is the southeastern fragment of the Svecofennian Belt. The metamorphic rocks of this region were traditionally regarded as constituents of a zonal metamorphosed complex composed largely of the Kalevian (late Paleoproterozoic) turbidite formation. Later data provided evidence for tectonic juxtaposition of the high-temperature core of the complex with less metamorphosed rocks. These relationships made it possible to distinguish the northern (ND) and southern (SD) domains.