Complex fabric development in Paleoproterozoic meta-quartzites of the Vastervik Basin, SE Sweden

The metamorphic siliciclastics of the Palaeoproterozoic Vastervik Basin locally display a complex fabric development caused by Si-metasomatism and ductile deformation. This is in contrast to large areas where primary sedimentary fabrics are remarkably well preserved. Fabric and texture analyses indicate that significant volumes of almost pure quartzites originated from arkosic sandstones due to metasomatic replacement of K-feldspar and plagioclase by quartz. These rheologically "soft" quartzites were preferentially affected by subsequent ductile deformation indicated by dynamic recrystallization fabrics and strongly developed quartz textures. It is suggested that both Si-metasomatism and ductile deformation are related to structural aureoles around minor granitic intrusions.